diff --git a/CMakeLists.txt b/CMakeLists.txt
index b4e0224f7..b2fc12c48 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -60,7 +60,7 @@ if (MSVC)
     # /bigobj (Increase Number of Sections in .Obj file)
     # error C3859: virtual memory range for PCH exceeded; please recompile with a command line option of '-Zm90' or greater
     # Generate symbols at every build target, even for the release.
-    add_compile_options(-bigobj -Zm316 /Zi)
+    add_compile_options(-bigobj -Zm520 /Zi)
 endif ()
 
 # Display and check CMAKE_PREFIX_PATH
diff --git a/resources/icons/mirroring_off.png b/resources/icons/mirroring_off.png
new file mode 100644
index 000000000..c16655271
Binary files /dev/null and b/resources/icons/mirroring_off.png differ
diff --git a/resources/icons/mirroring_on.png b/resources/icons/mirroring_on.png
new file mode 100644
index 000000000..6ddeccbe0
Binary files /dev/null and b/resources/icons/mirroring_on.png differ
diff --git a/resources/icons/mirroring_transparent.png b/resources/icons/mirroring_transparent.png
new file mode 100644
index 000000000..841010fcc
Binary files /dev/null and b/resources/icons/mirroring_transparent.png differ
diff --git a/src/PrusaSlicer.cpp b/src/PrusaSlicer.cpp
index fef1f6e7f..2becb8071 100644
--- a/src/PrusaSlicer.cpp
+++ b/src/PrusaSlicer.cpp
@@ -7,10 +7,13 @@
     #include <Windows.h>
     #include <wchar.h>
     #ifdef SLIC3R_GUI
+    extern "C" 
+    { 
         // Let the NVIDIA and AMD know we want to use their graphics card
         // on a dual graphics card system.
         __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
         __declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 1;
+    }
     #endif /* SLIC3R_GUI */
 #endif /* WIN32 */
 
@@ -241,8 +244,7 @@ int CLI::run(int argc, char **argv)
         } else if (opt_key == "cut" || opt_key == "cut_x" || opt_key == "cut_y") {
             std::vector<Model> new_models;
             for (auto &model : m_models) {
-                model.repair();
-                model.translate(0, 0, -model.bounding_box().min.z());  // align to z = 0                
+                model.translate(0, 0, -model.bounding_box().min.z());  // align to z = 0
 				size_t num_objects = model.objects.size();
 				for (size_t i = 0; i < num_objects; ++ i) {
 
@@ -301,8 +303,9 @@ int CLI::run(int argc, char **argv)
                 }
             }
         } else if (opt_key == "repair") {
-            for (auto &model : m_models)
-                model.repair();
+			// Models are repaired by default.
+            //for (auto &model : m_models)
+            //    model.repair();
         } else {
             boost::nowide::cerr << "error: option not implemented yet: " << opt_key << std::endl;
             return 1;
diff --git a/src/PrusaSlicer_app_msvc.cpp b/src/PrusaSlicer_app_msvc.cpp
index 5b01751b9..95dd4fb07 100644
--- a/src/PrusaSlicer_app_msvc.cpp
+++ b/src/PrusaSlicer_app_msvc.cpp
@@ -8,10 +8,13 @@
 #include <wchar.h>
 
 #ifdef SLIC3R_GUI
+extern "C" 
+{ 
 	// Let the NVIDIA and AMD know we want to use their graphics card
 	// on a dual graphics card system.
 	__declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
 	__declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 1;
+}
 #endif /* SLIC3R_GUI */
 
 #include <stdlib.h>
diff --git a/src/admesh/connect.cpp b/src/admesh/connect.cpp
index fb3213219..e729c8922 100644
--- a/src/admesh/connect.cpp
+++ b/src/admesh/connect.cpp
@@ -28,894 +28,729 @@
 #include <algorithm>
 #include <vector>
 
-#include <boost/detail/endian.hpp>
+#include <boost/predef/other/endian.h>
+#include <boost/log/trivial.hpp>
+// Boost pool: Don't use mutexes to synchronize memory allocation.
+#define BOOST_POOL_NO_MT
+#include <boost/pool/object_pool.hpp>
 
 #include "stl.h"
 
+struct HashEdge {
+	// Key of a hash edge: sorted vertices of the edge.
+	uint32_t       key[6];
+	// Compare two keys.
+	bool operator==(const HashEdge &rhs) const { return memcmp(key, rhs.key, sizeof(key)) == 0; }
+	bool operator!=(const HashEdge &rhs) const { return ! (*this == rhs); }
+	int  hash(int M) const { return ((key[0] / 11 + key[1] / 7 + key[2] / 3) ^ (key[3] / 11  + key[4] / 7 + key[5] / 3)) % M; }
 
-static void stl_match_neighbors_nearby(stl_file *stl,
-                                       stl_hash_edge *edge_a, stl_hash_edge *edge_b);
-static void stl_record_neighbors(stl_file *stl,
-                                 stl_hash_edge *edge_a, stl_hash_edge *edge_b);
-static void stl_initialize_facet_check_exact(stl_file *stl);
-static void stl_initialize_facet_check_nearby(stl_file *stl);
-static void stl_load_edge_exact(stl_file *stl, stl_hash_edge *edge, const stl_vertex *a, const stl_vertex *b);
-static int stl_load_edge_nearby(stl_file *stl, stl_hash_edge *edge,
-                                stl_vertex *a, stl_vertex *b, float tolerance);
-static void insert_hash_edge(stl_file *stl, stl_hash_edge edge,
-                             void (*match_neighbors)(stl_file *stl,
-                                 stl_hash_edge *edge_a, stl_hash_edge *edge_b));
-static int stl_compare_function(stl_hash_edge *edge_a, stl_hash_edge *edge_b);
-static void stl_free_edges(stl_file *stl);
-static void stl_remove_facet(stl_file *stl, int facet_number);
-static void stl_change_vertices(stl_file *stl, int facet_num, int vnot,
-                                stl_vertex new_vertex);
-static void stl_which_vertices_to_change(stl_file *stl, stl_hash_edge *edge_a,
-    stl_hash_edge *edge_b, int *facet1, int *vertex1,
-    int *facet2, int *vertex2,
-    stl_vertex *new_vertex1, stl_vertex *new_vertex2);
-static void stl_remove_degenerate(stl_file *stl, int facet);
-extern int stl_check_normal_vector(stl_file *stl,
-                                   int facet_num, int normal_fix_flag);
-static void stl_update_connects_remove_1(stl_file *stl, int facet_num);
+	// Index of a facet owning this edge.
+	int        facet_number;
+	// Index of this edge inside the facet with an index of facet_number.
+	// If this edge is stored backwards, which_edge is increased by 3.
+	int        which_edge;
+	HashEdge  *next;
+
+	void load_exact(stl_file *stl, const stl_vertex *a, const stl_vertex *b)
+	{
+		{
+	    	stl_vertex diff = (*a - *b).cwiseAbs();
+	    	float max_diff = std::max(diff(0), std::max(diff(1), diff(2)));
+	    	stl->stats.shortest_edge = std::min(max_diff, stl->stats.shortest_edge);
+	  	}
+
+	  	// Ensure identical vertex ordering of equal edges.
+	  	// This method is numerically robust.
+	  	if (vertex_lower(*a, *b)) {
+	  	} else {
+	  		// This edge is loaded backwards.
+		    std::swap(a, b);
+		    this->which_edge += 3;
+	  	}
+	  	memcpy(&this->key[0], a->data(), sizeof(stl_vertex));
+	  	memcpy(&this->key[3], b->data(), sizeof(stl_vertex));
+	  	// Switch negative zeros to positive zeros, so memcmp will consider them to be equal.
+	  	for (size_t i = 0; i < 6; ++ i) {
+	    	unsigned char *p = (unsigned char*)(this->key + i);
+	#if BOOST_ENDIAN_LITTLE_BYTE
+	    	if (p[0] == 0 && p[1] == 0 && p[2] == 0 && p[3] == 0x80)
+	      		// Negative zero, switch to positive zero.
+	      		p[3] = 0;
+	#else /* BOOST_ENDIAN_LITTLE_BYTE */
+	    	if (p[0] == 0x80 && p[1] == 0 && p[2] == 0 && p[3] == 0)
+	      		// Negative zero, switch to positive zero.
+	      		p[0] = 0;
+	#endif /* BOOST_ENDIAN_LITTLE_BYTE */
+	  	}
+	}
+
+	bool load_nearby(const stl_file *stl, const stl_vertex &a, const stl_vertex &b, float tolerance)
+	{
+		// Index of a grid cell spaced by tolerance.
+		typedef Eigen::Matrix<int32_t,  3, 1, Eigen::DontAlign> Vec3i;
+		Vec3i vertex1 = ((a - stl->stats.min) / tolerance).cast<int32_t>();
+		Vec3i vertex2 = ((b - stl->stats.min) / tolerance).cast<int32_t>();
+		static_assert(sizeof(Vec3i) == 12, "size of Vec3i incorrect");
+
+		if (vertex1 == vertex2)
+			// Both vertices hash to the same value
+			return false;
+
+		// Ensure identical vertex ordering of edges, which vertices land into equal grid cells.
+		// This method is numerically robust.
+		if ((vertex1[0] != vertex2[0]) ? 
+		    (vertex1[0] < vertex2[0]) : 
+		    ((vertex1[1] != vertex2[1]) ? 
+		        (vertex1[1] < vertex2[1]) : 
+		        (vertex1[2] < vertex2[2]))) {
+			memcpy(&this->key[0], vertex1.data(), sizeof(stl_vertex));
+			memcpy(&this->key[3], vertex2.data(), sizeof(stl_vertex));
+		} else {
+			memcpy(&this->key[0], vertex2.data(), sizeof(stl_vertex));
+			memcpy(&this->key[3], vertex1.data(), sizeof(stl_vertex));
+			this->which_edge += 3; /* this edge is loaded backwards */
+		}
+		return true;
+	}
+
+private:
+	inline bool vertex_lower(const stl_vertex &a, const stl_vertex &b) {
+	  	return (a(0) != b(0)) ? (a(0) < b(0)) :
+	           ((a(1) != b(1)) ? (a(1) < b(1)) : (a(2) < b(2)));
+	}
+};
+
+struct HashTableEdges {
+	HashTableEdges(size_t number_of_faces) {
+		this->M = (int)hash_size_from_nr_faces(number_of_faces);
+		this->heads.assign(this->M, nullptr);
+		this->tail = pool.construct();
+		this->tail->next = this->tail;
+		for (int i = 0; i < this->M; ++ i)
+			this->heads[i] = this->tail;
+	}
+	~HashTableEdges() {
+#ifndef NDEBUG
+		for (int i = 0; i < this->M; ++ i)
+	    	for (HashEdge *temp = this->heads[i]; this->heads[i] != this->tail; temp = this->heads[i])
+	        	++ this->freed;
+		this->tail = nullptr;
+#endif /* NDEBUG */
+	}
+
+	void insert_edge_exact(stl_file *stl, const HashEdge &edge)
+	{
+		this->insert_edge(stl, edge, [stl](const HashEdge& edge1, const HashEdge& edge2) { record_neighbors(stl, edge1, edge2); });
+	}
+
+	void insert_edge_nearby(stl_file *stl, const HashEdge &edge)
+	{
+		this->insert_edge(stl, edge, [stl](const HashEdge& edge1, const HashEdge& edge2) { match_neighbors_nearby(stl, edge1, edge2); });
+	}
+
+	// Hash table on edges
+	std::vector<HashEdge*> 	heads;
+	HashEdge* 				tail;
+	int           			M;
+	boost::object_pool<HashEdge> pool;
+
+#ifndef NDEBUG
+	size_t 					malloced   	= 0;
+	size_t 					freed 	  	= 0;
+	size_t 					collisions 	= 0;
+#endif /* NDEBUG */
+
+private:
+	static inline size_t hash_size_from_nr_faces(const size_t nr_faces)
+	{
+		// Good primes for addressing a cca. 30 bit space.
+		// https://planetmath.org/goodhashtableprimes
+		static std::vector<uint32_t> primes{ 98317, 196613, 393241, 786433, 1572869, 3145739, 6291469, 12582917, 25165843, 50331653, 100663319, 201326611, 402653189, 805306457, 1610612741 };
+		// Find a prime number for 50% filling of the shared triangle edges in the mesh.
+		auto it = std::upper_bound(primes.begin(), primes.end(), nr_faces * 3 * 2 - 1);
+		return (it == primes.end()) ? primes.back() : *it;
+	}
+
+
+	// MatchNeighbors(stl_file *stl, const HashEdge &edge_a, const HashEdge &edge_b)
+	template<typename MatchNeighbors>
+	void insert_edge(stl_file *stl, const HashEdge &edge, MatchNeighbors match_neighbors)
+	{
+		int       chain_number = edge.hash(this->M);
+		HashEdge *link         = this->heads[chain_number];
+		if (link == this->tail) {
+			// This list doesn't have any edges currently in it.  Add this one.
+			HashEdge *new_edge = pool.construct(edge);
+#ifndef NDEBUG
+			++ this->malloced;
+#endif /* NDEBUG */
+			new_edge->next = this->tail;
+			this->heads[chain_number] = new_edge;
+		} else if (edges_equal(edge, *link)) {
+			// This is a match.  Record result in neighbors list.
+			match_neighbors(edge, *link);
+			// Delete the matched edge from the list.
+			this->heads[chain_number] = link->next;
+			// pool.destroy(link);
+#ifndef NDEBUG
+			++ this->freed;
+#endif /* NDEBUG */
+		} else {
+			// Continue through the rest of the list.
+			for (;;) {
+				if (link->next == this->tail) {
+					// This is the last item in the list. Insert a new edge.
+					HashEdge *new_edge = pool.construct();
+#ifndef NDEBUG
+					++ this->malloced;
+#endif /* NDEBUG */
+					*new_edge = edge;
+					new_edge->next = this->tail;
+					link->next = new_edge;
+#ifndef NDEBUG
+					++ this->collisions;
+#endif /* NDEBUG */
+					break;
+				}
+				if (edges_equal(edge, *link->next)) {
+					// This is a match.  Record result in neighbors list.
+					match_neighbors(edge, *link->next);
+					// Delete the matched edge from the list.
+					HashEdge *temp = link->next;
+					link->next = link->next->next;
+					// pool.destroy(temp);
+#ifndef NDEBUG
+					++ this->freed;
+#endif /* NDEBUG */
+					break;
+				}
+				// This is not a match.  Go to the next link.
+				link = link->next;
+#ifndef NDEBUG
+				++ this->collisions;
+#endif /* NDEBUG */
+			}
+		}
+	}
+
+	// Edges equal for hashing. Edgesof different facet are allowed to be matched.
+	static inline bool edges_equal(const HashEdge &edge_a, const HashEdge &edge_b)
+	{
+	    return edge_a.facet_number != edge_b.facet_number && edge_a == edge_b;
+	}
+
+	static void record_neighbors(stl_file *stl, const HashEdge &edge_a, const HashEdge &edge_b)
+	{
+		// Facet a's neighbor is facet b
+		stl->neighbors_start[edge_a.facet_number].neighbor[edge_a.which_edge % 3] = edge_b.facet_number;	/* sets the .neighbor part */
+		stl->neighbors_start[edge_a.facet_number].which_vertex_not[edge_a.which_edge % 3] = (edge_b.which_edge + 2) % 3; /* sets the .which_vertex_not part */
+
+		// Facet b's neighbor is facet a
+		stl->neighbors_start[edge_b.facet_number].neighbor[edge_b.which_edge % 3] = edge_a.facet_number;	/* sets the .neighbor part */
+		stl->neighbors_start[edge_b.facet_number].which_vertex_not[edge_b.which_edge % 3] = (edge_a.which_edge + 2) % 3; /* sets the .which_vertex_not part */
+
+		if (((edge_a.which_edge < 3) && (edge_b.which_edge < 3)) || ((edge_a.which_edge > 2) && (edge_b.which_edge > 2))) {
+			// These facets are oriented in opposite directions, their normals are probably messed up.
+			stl->neighbors_start[edge_a.facet_number].which_vertex_not[edge_a.which_edge % 3] += 3;
+			stl->neighbors_start[edge_b.facet_number].which_vertex_not[edge_b.which_edge % 3] += 3;
+		}
+
+		// Count successful connects:
+		// Total connects:
+		stl->stats.connected_edges += 2;
+		// Count individual connects:
+		switch (stl->neighbors_start[edge_a.facet_number].num_neighbors()) {
+		case 1:	++ stl->stats.connected_facets_1_edge; break;
+		case 2: ++ stl->stats.connected_facets_2_edge; break;
+		case 3: ++ stl->stats.connected_facets_3_edge; break;
+		default: assert(false);
+		}
+		switch (stl->neighbors_start[edge_b.facet_number].num_neighbors()) {
+		case 1:	++ stl->stats.connected_facets_1_edge; break;
+		case 2: ++ stl->stats.connected_facets_2_edge; break;
+		case 3: ++ stl->stats.connected_facets_3_edge; break;
+		default: assert(false);
+		}
+	}
+
+	static void match_neighbors_nearby(stl_file *stl, const HashEdge &edge_a, const HashEdge &edge_b)
+	{
+		record_neighbors(stl, edge_a, edge_b);
+
+		// Which vertices to change
+		int facet1 = -1;
+		int facet2 = -1;
+		int vertex1, vertex2;
+		stl_vertex new_vertex1, new_vertex2;
+		{
+			int v1a; // pair 1, facet a
+			int v1b; // pair 1, facet b
+			int v2a; // pair 2, facet a
+			int v2b; // pair 2, facet b
+			// Find first pair.
+			if (edge_a.which_edge < 3) {
+				v1a = edge_a.which_edge;
+				v2a = (edge_a.which_edge + 1) % 3;
+			} else {
+				v2a = edge_a.which_edge % 3;
+				v1a = (edge_a.which_edge + 1) % 3;
+			}
+			if (edge_b.which_edge < 3) {
+				v1b = edge_b.which_edge;
+				v2b = (edge_b.which_edge + 1) % 3;
+			} else {
+				v2b = edge_b.which_edge % 3;
+				v1b = (edge_b.which_edge + 1) % 3;
+			}
+
+			// Of the first pair, which vertex, if any, should be changed
+			if (stl->facet_start[edge_a.facet_number].vertex[v1a] != stl->facet_start[edge_b.facet_number].vertex[v1b]) {
+				// These facets are different.
+				if (   (stl->neighbors_start[edge_a.facet_number].neighbor[v1a] == -1)
+			        && (stl->neighbors_start[edge_a.facet_number].neighbor[(v1a + 2) % 3] == -1)) {
+			  		// This vertex has no neighbors.  This is a good one to change.
+			  		facet1 = edge_a.facet_number;
+			  		vertex1 = v1a;
+			  		new_vertex1 = stl->facet_start[edge_b.facet_number].vertex[v1b];
+				} else {
+				  	facet1 = edge_b.facet_number;
+			  		vertex1 = v1b;
+			  		new_vertex1 = stl->facet_start[edge_a.facet_number].vertex[v1a];
+				}
+			}
+
+			// Of the second pair, which vertex, if any, should be changed.
+			if (stl->facet_start[edge_a.facet_number].vertex[v2a] == stl->facet_start[edge_b.facet_number].vertex[v2b]) {
+				// These facets are different.
+				if (  (stl->neighbors_start[edge_a.facet_number].neighbor[v2a] == -1)
+			       && (stl->neighbors_start[edge_a.facet_number].neighbor[(v2a + 2) % 3] == -1)) {
+			  		// This vertex has no neighbors.  This is a good one to change.
+			  		facet2 = edge_a.facet_number;
+			  		vertex2 = v2a;
+			  		new_vertex2 = stl->facet_start[edge_b.facet_number].vertex[v2b];
+				} else {
+			  		facet2 = edge_b.facet_number;
+			  		vertex2 = v2b;
+			  		new_vertex2 = stl->facet_start[edge_a.facet_number].vertex[v2a];
+				}
+			}
+		}
+
+		auto change_vertices = [stl](int facet_num, int vnot, stl_vertex new_vertex)
+		{
+			int first_facet = facet_num;
+			bool direction = false;
+
+			for (;;) {
+				int pivot_vertex;
+				int next_edge;
+				if (vnot > 2) {
+					if (direction) {
+						pivot_vertex = (vnot + 1) % 3;
+						next_edge = vnot % 3;
+					}
+					else {
+						pivot_vertex = (vnot + 2) % 3;
+						next_edge = pivot_vertex;
+					}
+					direction = !direction;
+				}
+				else {
+					if (direction) {
+						pivot_vertex = (vnot + 2) % 3;
+						next_edge = pivot_vertex;
+					}
+					else {
+						pivot_vertex = (vnot + 1) % 3;
+						next_edge = vnot;
+					}
+				}
+	#if 0
+				if (stl->facet_start[facet_num].vertex[pivot_vertex](0) == new_vertex(0) &&
+					stl->facet_start[facet_num].vertex[pivot_vertex](1) == new_vertex(1) &&
+					stl->facet_start[facet_num].vertex[pivot_vertex](2) == new_vertex(2))
+					printf("Changing vertex %f,%f,%f: Same !!!\r\n", new_vertex(0), new_vertex(1), new_vertex(2));
+				else {
+					if (stl->facet_start[facet_num].vertex[pivot_vertex](0) != new_vertex(0))
+						printf("Changing coordinate x, vertex %e (0x%08x) to %e(0x%08x)\r\n",
+							stl->facet_start[facet_num].vertex[pivot_vertex](0),
+							*reinterpret_cast<const int*>(&stl->facet_start[facet_num].vertex[pivot_vertex](0)),
+							new_vertex(0),
+							*reinterpret_cast<const int*>(&new_vertex(0)));
+					if (stl->facet_start[facet_num].vertex[pivot_vertex](1) != new_vertex(1))
+						printf("Changing coordinate x, vertex %e (0x%08x) to %e(0x%08x)\r\n",
+							stl->facet_start[facet_num].vertex[pivot_vertex](1),
+							*reinterpret_cast<const int*>(&stl->facet_start[facet_num].vertex[pivot_vertex](1)),
+							new_vertex(1),
+							*reinterpret_cast<const int*>(&new_vertex(1)));
+					if (stl->facet_start[facet_num].vertex[pivot_vertex](2) != new_vertex(2))
+						printf("Changing coordinate x, vertex %e (0x%08x) to %e(0x%08x)\r\n",
+							stl->facet_start[facet_num].vertex[pivot_vertex](2),
+							*reinterpret_cast<const int*>(&stl->facet_start[facet_num].vertex[pivot_vertex](2)),
+							new_vertex(2),
+							*reinterpret_cast<const int*>(&new_vertex(2)));
+				}
+	#endif
+				stl->facet_start[facet_num].vertex[pivot_vertex] = new_vertex;
+				vnot = stl->neighbors_start[facet_num].which_vertex_not[next_edge];
+				facet_num = stl->neighbors_start[facet_num].neighbor[next_edge];
+				if (facet_num == -1)
+					break;
+
+				if (facet_num == first_facet) {
+					// back to the beginning
+					BOOST_LOG_TRIVIAL(info) << "Back to the first facet changing vertices: probably a mobius part. Try using a smaller tolerance or don't do a nearby check.";
+					return;
+				}
+			}
+		};
+
+		if (facet1 != -1) {
+			int vnot1 = (facet1 == edge_a.facet_number) ? 
+		  		(edge_a.which_edge + 2) % 3 :
+				(edge_b.which_edge + 2) % 3;
+			if (((vnot1 + 2) % 3) == vertex1)
+		  		vnot1 += 3;
+			change_vertices(facet1, vnot1, new_vertex1);
+		}
+		if (facet2 != -1) {
+			int vnot2 = (facet2 == edge_a.facet_number) ?
+		  		(edge_a.which_edge + 2) % 3 :
+				(edge_b.which_edge + 2) % 3;
+			if (((vnot2 + 2) % 3) == vertex2)
+		  		vnot2 += 3;
+			change_vertices(facet2, vnot2, new_vertex2);
+		}
+		stl->stats.edges_fixed += 2;
+	}
+};
 
 // This function builds the neighbors list.  No modifications are made
 // to any of the facets.  The edges are said to match only if all six
 // floats of the first edge matches all six floats of the second edge.
 void stl_check_facets_exact(stl_file *stl)
 {
-  if (stl->error)
-	  return;
+  	stl->stats.connected_edges         = 0;
+  	stl->stats.connected_facets_1_edge = 0;
+  	stl->stats.connected_facets_2_edge = 0;
+  	stl->stats.connected_facets_3_edge = 0;
 
-  stl->stats.connected_edges = 0;
-  stl->stats.connected_facets_1_edge = 0;
-  stl->stats.connected_facets_2_edge = 0;
-  stl->stats.connected_facets_3_edge = 0;
+  	// If any two of the three vertices are found to be exactally the same, call them degenerate and remove the facet.
+  	// Do it before the next step, as the next step stores references to the face indices in the hash tables and removing a facet
+  	// will break the references.
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets;) {
+		stl_facet &facet = stl->facet_start[i];
+	  	if (facet.vertex[0] == facet.vertex[1] || facet.vertex[1] == facet.vertex[2] || facet.vertex[0] == facet.vertex[2]) {
+		  	// Remove the degenerate facet.
+		  	facet = stl->facet_start[-- stl->stats.number_of_facets];
+			stl->facet_start.pop_back();
+			stl->neighbors_start.pop_back();
+		  	stl->stats.facets_removed += 1;
+		  	stl->stats.degenerate_facets += 1;
+	  	} else
+		  	++ i;
+  	}
 
-  // If any two of the three vertices are found to be exactally the same, call them degenerate and remove the facet.
-  // Do it before the next step, as the next step stores references to the face indices in the hash tables and removing a facet
-  // will break the references.
-  for (int i = 0; i < stl->stats.number_of_facets;) {
-	  stl_facet &facet = stl->facet_start[i];
-	  if (facet.vertex[0] == facet.vertex[1] || facet.vertex[1] == facet.vertex[2] || facet.vertex[0] == facet.vertex[2]) {
-		  // Remove the degenerate facet.
-		  facet = stl->facet_start[--stl->stats.number_of_facets];
-		  stl->stats.facets_removed += 1;
-		  stl->stats.degenerate_facets += 1;
-	  } else
-		  ++ i;
-  }
+  	// Initialize hash table.
+  	HashTableEdges hash_table(stl->stats.number_of_facets);
+	for (auto &neighbor : stl->neighbors_start)
+		neighbor.reset();
 
-  // Connect neighbor edges.
-  stl_initialize_facet_check_exact(stl);
-  for (int i = 0; i < stl->stats.number_of_facets; i++) {
-	const stl_facet &facet = stl->facet_start[i];
-    for (int j = 0; j < 3; j++) {
-	  stl_hash_edge  edge;
-	  edge.facet_number = i;
-      edge.which_edge = j;
-      stl_load_edge_exact(stl, &edge, &facet.vertex[j], &facet.vertex[(j + 1) % 3]);
-      insert_hash_edge(stl, edge, stl_record_neighbors);
-    }
-  }
-  stl_free_edges(stl);
+  	// Connect neighbor edges.
+	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+		const stl_facet &facet = stl->facet_start[i];
+		for (int j = 0; j < 3; ++ j) {
+			HashEdge edge;
+			edge.facet_number = i;
+			edge.which_edge = j;
+			edge.load_exact(stl, &facet.vertex[j], &facet.vertex[(j + 1) % 3]);
+			hash_table.insert_edge_exact(stl, edge);
+		}
+	}
 
 #if 0
-  printf("Number of faces: %d, number of manifold edges: %d, number of connected edges: %d, number of unconnected edges: %d\r\n", 
-    stl->stats.number_of_facets, stl->stats.number_of_facets * 3, 
-    stl->stats.connected_edges, stl->stats.number_of_facets * 3 - stl->stats.connected_edges);
+	printf("Number of faces: %d, number of manifold edges: %d, number of connected edges: %d, number of unconnected edges: %d\r\n", 
+    	stl->stats.number_of_facets, stl->stats.number_of_facets * 3, 
+    	stl->stats.connected_edges, stl->stats.number_of_facets * 3 - stl->stats.connected_edges);
 #endif
 }
 
-static void stl_load_edge_exact(stl_file *stl, stl_hash_edge *edge, const stl_vertex *a, const stl_vertex *b) {
-
-  if (stl->error) return;
-
-  {
-    stl_vertex diff = (*a - *b).cwiseAbs();
-    float max_diff = std::max(diff(0), std::max(diff(1), diff(2)));
-    stl->stats.shortest_edge = std::min(max_diff, stl->stats.shortest_edge);
-  }
-
-  // Ensure identical vertex ordering of equal edges.
-  // This method is numerically robust.
-  if (stl_vertex_lower(*a, *b)) {
-  } else {
-    std::swap(a, b);
-    edge->which_edge += 3; /* this edge is loaded backwards */
-  }
-  memcpy(&edge->key[0], a->data(), sizeof(stl_vertex));
-  memcpy(&edge->key[3], b->data(), sizeof(stl_vertex));
-  // Switch negative zeros to positive zeros, so memcmp will consider them to be equal.
-  for (size_t i = 0; i < 6; ++ i) {
-    unsigned char *p = (unsigned char*)(edge->key + i);
-#ifdef BOOST_LITTLE_ENDIAN
-    if (p[0] == 0 && p[1] == 0 && p[2] == 0 && p[3] == 0x80)
-      // Negative zero, switch to positive zero.
-      p[3] = 0;
-#else /* BOOST_LITTLE_ENDIAN */
-    if (p[0] == 0x80 && p[1] == 0 && p[2] == 0 && p[3] == 0)
-      // Negative zero, switch to positive zero.
-      p[0] = 0;
-#endif /* BOOST_LITTLE_ENDIAN */
-  }
-}
-
-static inline size_t hash_size_from_nr_faces(const size_t nr_faces)
-{
-	// Good primes for addressing a cca. 30 bit space.
-	// https://planetmath.org/goodhashtableprimes
-	static std::vector<uint32_t> primes{ 98317, 196613, 393241, 786433, 1572869, 3145739, 6291469, 12582917, 25165843, 50331653, 100663319, 201326611, 402653189, 805306457, 1610612741 };
-	// Find a prime number for 50% filling of the shared triangle edges in the mesh.
-	auto it = std::upper_bound(primes.begin(), primes.end(), nr_faces * 3 * 2 - 1);
-	return (it == primes.end()) ? primes.back() : *it;
-}
-
-static void
-stl_initialize_facet_check_exact(stl_file *stl) {
-  int i;
-
-  if (stl->error) return;
-
-  stl->stats.malloced = 0;
-  stl->stats.freed = 0;
-  stl->stats.collisions = 0;
-
-  stl->M = hash_size_from_nr_faces(stl->stats.number_of_facets);
-
-  for (i = 0; i < stl->stats.number_of_facets ; i++) {
-    /* initialize neighbors list to -1 to mark unconnected edges */
-    stl->neighbors_start[i].neighbor[0] = -1;
-    stl->neighbors_start[i].neighbor[1] = -1;
-    stl->neighbors_start[i].neighbor[2] = -1;
-  }
-
-  stl->heads = (stl_hash_edge**)calloc(stl->M, sizeof(*stl->heads));
-  if(stl->heads == NULL) perror("stl_initialize_facet_check_exact");
-
-  stl->tail = (stl_hash_edge*)malloc(sizeof(stl_hash_edge));
-  if(stl->tail == NULL) perror("stl_initialize_facet_check_exact");
-
-  stl->tail->next = stl->tail;
-
-  for(i = 0; i < stl->M; i++) {
-    stl->heads[i] = stl->tail;
-  }
-}
-
-static void insert_hash_edge(stl_file *stl, stl_hash_edge edge,
-                 void (*match_neighbors)(stl_file *stl,
-                     stl_hash_edge *edge_a, stl_hash_edge *edge_b))
-{
-  if (stl->error) return;
-
-  int            chain_number = edge.hash(stl->M);
-  stl_hash_edge *link = stl->heads[chain_number];
-
-  stl_hash_edge *new_edge;
-  stl_hash_edge *temp;
-  if(link == stl->tail) {
-    /* This list doesn't have any edges currently in it.  Add this one. */
-    new_edge = (stl_hash_edge*)malloc(sizeof(stl_hash_edge));
-    if(new_edge == NULL) perror("insert_hash_edge");
-    stl->stats.malloced++;
-    *new_edge = edge;
-    new_edge->next = stl->tail;
-    stl->heads[chain_number] = new_edge;
-    return;
-  } else  if(!stl_compare_function(&edge, link)) {
-    /* This is a match.  Record result in neighbors list. */
-    match_neighbors(stl, &edge, link);
-    /* Delete the matched edge from the list. */
-    stl->heads[chain_number] = link->next;
-    free(link);
-    stl->stats.freed++;
-    return;
-  } else {
-    /* Continue through the rest of the list */
-    for(;;) {
-      if(link->next == stl->tail) {
-        /* This is the last item in the list. Insert a new edge. */
-        new_edge = (stl_hash_edge*)malloc(sizeof(stl_hash_edge));
-        if(new_edge == NULL) perror("insert_hash_edge");
-        stl->stats.malloced++;
-        *new_edge = edge;
-        new_edge->next = stl->tail;
-        link->next = new_edge;
-        stl->stats.collisions++;
-        return;
-      } else  if(!stl_compare_function(&edge, link->next)) {
-        /* This is a match.  Record result in neighbors list. */
-        match_neighbors(stl, &edge, link->next);
-
-        /* Delete the matched edge from the list. */
-        temp = link->next;
-        link->next = link->next->next;
-        free(temp);
-        stl->stats.freed++;
-        return;
-      } else {
-        /* This is not a match.  Go to the next link */
-        link = link->next;
-        stl->stats.collisions++;
-      }
-    }
-  }
-}
-
-// Return 1 if the edges are not matched.
-static inline int stl_compare_function(stl_hash_edge *edge_a, stl_hash_edge *edge_b)
-{
-    // Don't match edges of the same facet
-    return (edge_a->facet_number == edge_b->facet_number) || (*edge_a != *edge_b);
-}
-
 void stl_check_facets_nearby(stl_file *stl, float tolerance)
 {
-  if (stl->error)
-    return;
+  	if (  (stl->stats.connected_facets_1_edge == stl->stats.number_of_facets)
+       && (stl->stats.connected_facets_2_edge == stl->stats.number_of_facets)
+       && (stl->stats.connected_facets_3_edge == stl->stats.number_of_facets)) {
+    	// No need to check any further.  All facets are connected.
+    	return;
+  	}
 
-  if(   (stl->stats.connected_facets_1_edge == stl->stats.number_of_facets)
-        && (stl->stats.connected_facets_2_edge == stl->stats.number_of_facets)
-        && (stl->stats.connected_facets_3_edge == stl->stats.number_of_facets)) {
-    /* No need to check any further.  All facets are connected */
-    return;
-  }
-
-  stl_initialize_facet_check_nearby(stl);
-
-  for (int i = 0; i < stl->stats.number_of_facets; ++ i) {
-    //FIXME is the copy necessary?
-    stl_facet facet = stl->facet_start[i];
-    for (int j = 0; j < 3; j++) {
-      if(stl->neighbors_start[i].neighbor[j] == -1) {
-        stl_hash_edge edge;
-        edge.facet_number = i;
-        edge.which_edge = j;
-        if(stl_load_edge_nearby(stl, &edge, &facet.vertex[j],
-                                &facet.vertex[(j + 1) % 3],
-                                tolerance)) {
-          /* only insert edges that have different keys */
-          insert_hash_edge(stl, edge, stl_match_neighbors_nearby);
-        }
-      }
-    }
-  }
-
-  stl_free_edges(stl);
-}
-
-static int stl_load_edge_nearby(stl_file *stl, stl_hash_edge *edge, stl_vertex *a, stl_vertex *b, float tolerance)
-{
-  // Index of a grid cell spaced by tolerance.
-  typedef Eigen::Matrix<int32_t,  3, 1, Eigen::DontAlign> Vec3i;
-  Vec3i vertex1 = ((*a - stl->stats.min) / tolerance).cast<int32_t>();
-  Vec3i vertex2 = ((*b - stl->stats.min) / tolerance).cast<int32_t>();
-  static_assert(sizeof(Vec3i) == 12, "size of Vec3i incorrect");
-
-  if (vertex1 == vertex2)
-    // Both vertices hash to the same value
-    return 0;
-
-  // Ensure identical vertex ordering of edges, which vertices land into equal grid cells.
-  // This method is numerically robust.
-  if ((vertex1[0] != vertex2[0]) ? 
-        (vertex1[0] < vertex2[0]) : 
-        ((vertex1[1] != vertex2[1]) ? 
-            (vertex1[1] < vertex2[1]) : 
-            (vertex1[2] < vertex2[2]))) {
-    memcpy(&edge->key[0], vertex1.data(), sizeof(stl_vertex));
-    memcpy(&edge->key[3], vertex2.data(), sizeof(stl_vertex));
-  } else {
-    memcpy(&edge->key[0], vertex2.data(), sizeof(stl_vertex));
-    memcpy(&edge->key[3], vertex1.data(), sizeof(stl_vertex));
-    edge->which_edge += 3; /* this edge is loaded backwards */
-  }
-  return 1;
-}
-
-static void stl_free_edges(stl_file *stl)
-{
-  if (stl->error)
-    return;
-
-  if(stl->stats.malloced != stl->stats.freed) {
-    for (int i = 0; i < stl->M; i++) {
-      for (stl_hash_edge *temp = stl->heads[i]; stl->heads[i] != stl->tail; temp = stl->heads[i]) {
-        stl->heads[i] = stl->heads[i]->next;
-        free(temp);
-        ++ stl->stats.freed;
-      }
-    }
-  }
-  free(stl->heads);
-  stl->heads = nullptr;
-  free(stl->tail);
-  stl->tail = nullptr;
-}
-
-static void stl_initialize_facet_check_nearby(stl_file *stl)
-{
-  int i;
-
-  if (stl->error) return;
-
-  stl->stats.malloced = 0;
-  stl->stats.freed = 0;
-  stl->stats.collisions = 0;
-
-  /*  tolerance = STL_MAX(stl->stats.shortest_edge, tolerance);*/
-  /*  tolerance = STL_MAX((stl->stats.bounding_diameter / 500000.0), tolerance);*/
-  /*  tolerance *= 0.5;*/
-
-  stl->M = hash_size_from_nr_faces(stl->stats.number_of_facets);
-
-  stl->heads = (stl_hash_edge**)calloc(stl->M, sizeof(*stl->heads));
-  if(stl->heads == NULL) perror("stl_initialize_facet_check_nearby");
-
-  stl->tail = (stl_hash_edge*)malloc(sizeof(stl_hash_edge));
-  if(stl->tail == NULL) perror("stl_initialize_facet_check_nearby");
-
-  stl->tail->next = stl->tail;
-
-  for(i = 0; i < stl->M; i++) {
-    stl->heads[i] = stl->tail;
-  }
-}
-
-
-
-static void
-stl_record_neighbors(stl_file *stl,
-                     stl_hash_edge *edge_a, stl_hash_edge *edge_b) {
-  int i;
-  int j;
-
-  if (stl->error) return;
-
-  /* Facet a's neighbor is facet b */
-  stl->neighbors_start[edge_a->facet_number].neighbor[edge_a->which_edge % 3] =
-    edge_b->facet_number;	/* sets the .neighbor part */
-
-  stl->neighbors_start[edge_a->facet_number].
-  which_vertex_not[edge_a->which_edge % 3] =
-    (edge_b->which_edge + 2) % 3; /* sets the .which_vertex_not part */
-
-  /* Facet b's neighbor is facet a */
-  stl->neighbors_start[edge_b->facet_number].neighbor[edge_b->which_edge % 3] =
-    edge_a->facet_number;	/* sets the .neighbor part */
-
-  stl->neighbors_start[edge_b->facet_number].
-  which_vertex_not[edge_b->which_edge % 3] =
-    (edge_a->which_edge + 2) % 3; /* sets the .which_vertex_not part */
-
-  if(   ((edge_a->which_edge < 3) && (edge_b->which_edge < 3))
-        || ((edge_a->which_edge > 2) && (edge_b->which_edge > 2))) {
-    /* these facets are oriented in opposite directions.  */
-    /*  their normals are probably messed up. */
-    stl->neighbors_start[edge_a->facet_number].
-    which_vertex_not[edge_a->which_edge % 3] += 3;
-    stl->neighbors_start[edge_b->facet_number].
-    which_vertex_not[edge_b->which_edge % 3] += 3;
-  }
-
-
-  /* Count successful connects */
-  /* Total connects */
-  stl->stats.connected_edges += 2;
-  /* Count individual connects */
-  i = ((stl->neighbors_start[edge_a->facet_number].neighbor[0] == -1) +
-       (stl->neighbors_start[edge_a->facet_number].neighbor[1] == -1) +
-       (stl->neighbors_start[edge_a->facet_number].neighbor[2] == -1));
-  j = ((stl->neighbors_start[edge_b->facet_number].neighbor[0] == -1) +
-       (stl->neighbors_start[edge_b->facet_number].neighbor[1] == -1) +
-       (stl->neighbors_start[edge_b->facet_number].neighbor[2] == -1));
-  if(i == 2) {
-    stl->stats.connected_facets_1_edge +=1;
-  } else if(i == 1) {
-    stl->stats.connected_facets_2_edge +=1;
-  } else {
-    stl->stats.connected_facets_3_edge +=1;
-  }
-  if(j == 2) {
-    stl->stats.connected_facets_1_edge +=1;
-  } else if(j == 1) {
-    stl->stats.connected_facets_2_edge +=1;
-  } else {
-    stl->stats.connected_facets_3_edge +=1;
-  }
-}
-
-static void stl_match_neighbors_nearby(stl_file *stl, stl_hash_edge *edge_a, stl_hash_edge *edge_b)
-{
-  int facet1;
-  int facet2;
-  int vertex1;
-  int vertex2;
-  int vnot1;
-  int vnot2;
-  stl_vertex new_vertex1;
-  stl_vertex new_vertex2;
-
-  if (stl->error) return;
-
-  stl_record_neighbors(stl, edge_a, edge_b);
-  stl_which_vertices_to_change(stl, edge_a, edge_b, &facet1, &vertex1,
-                               &facet2, &vertex2, &new_vertex1, &new_vertex2);
-  if(facet1 != -1) {
-    if(facet1 == edge_a->facet_number) {
-      vnot1 = (edge_a->which_edge + 2) % 3;
-    } else {
-      vnot1 = (edge_b->which_edge + 2) % 3;
-    }
-    if(((vnot1 + 2) % 3) == vertex1) {
-      vnot1 += 3;
-    }
-    stl_change_vertices(stl, facet1, vnot1, new_vertex1);
-  }
-  if(facet2 != -1) {
-    if(facet2 == edge_a->facet_number) {
-      vnot2 = (edge_a->which_edge + 2) % 3;
-    } else {
-      vnot2 = (edge_b->which_edge + 2) % 3;
-    }
-    if(((vnot2 + 2) % 3) == vertex2) {
-      vnot2 += 3;
-    }
-    stl_change_vertices(stl, facet2, vnot2, new_vertex2);
-  }
-  stl->stats.edges_fixed += 2;
-}
-
-
-static void stl_change_vertices(stl_file *stl, int facet_num, int vnot, stl_vertex new_vertex) {
-  int first_facet;
-  int direction;
-  int next_edge;
-  int pivot_vertex;
-
-  if (stl->error) return;
-
-  first_facet = facet_num;
-  direction = 0;
-
-  for(;;) {
-    if(vnot > 2) {
-      if(direction == 0) {
-        pivot_vertex = (vnot + 2) % 3;
-        next_edge = pivot_vertex;
-        direction = 1;
-      } else {
-        pivot_vertex = (vnot + 1) % 3;
-        next_edge = vnot % 3;
-        direction = 0;
-      }
-    } else {
-      if(direction == 0) {
-        pivot_vertex = (vnot + 1) % 3;
-        next_edge = vnot;
-      } else {
-        pivot_vertex = (vnot + 2) % 3;
-        next_edge = pivot_vertex;
-      }
-    }
-#if 0
-    if (stl->facet_start[facet_num].vertex[pivot_vertex](0) == new_vertex(0) &&
-        stl->facet_start[facet_num].vertex[pivot_vertex](1) == new_vertex(1) &&
-        stl->facet_start[facet_num].vertex[pivot_vertex](2) == new_vertex(2))
-      printf("Changing vertex %f,%f,%f: Same !!!\r\n", 
-        new_vertex(0), new_vertex(1), new_vertex(2));
-    else {
-      if (stl->facet_start[facet_num].vertex[pivot_vertex](0) != new_vertex(0))
-        printf("Changing coordinate x, vertex %e (0x%08x) to %e(0x%08x)\r\n", 
-          stl->facet_start[facet_num].vertex[pivot_vertex](0),
-          *reinterpret_cast<const int*>(&stl->facet_start[facet_num].vertex[pivot_vertex](0)),
-          new_vertex(0),
-          *reinterpret_cast<const int*>(&new_vertex(0)));
-      if (stl->facet_start[facet_num].vertex[pivot_vertex](1) != new_vertex(1))
-        printf("Changing coordinate x, vertex %e (0x%08x) to %e(0x%08x)\r\n", 
-          stl->facet_start[facet_num].vertex[pivot_vertex](1),
-          *reinterpret_cast<const int*>(&stl->facet_start[facet_num].vertex[pivot_vertex](1)),
-          new_vertex(1),
-          *reinterpret_cast<const int*>(&new_vertex(1)));
-      if (stl->facet_start[facet_num].vertex[pivot_vertex](2) != new_vertex(2))
-        printf("Changing coordinate x, vertex %e (0x%08x) to %e(0x%08x)\r\n", 
-          stl->facet_start[facet_num].vertex[pivot_vertex](2),
-          *reinterpret_cast<const int*>(&stl->facet_start[facet_num].vertex[pivot_vertex](2)),
-          new_vertex(2),
-          *reinterpret_cast<const int*>(&new_vertex(2)));
-    }
-#endif
-    stl->facet_start[facet_num].vertex[pivot_vertex] = new_vertex;
-    vnot = stl->neighbors_start[facet_num].which_vertex_not[next_edge];
-    facet_num = stl->neighbors_start[facet_num].neighbor[next_edge];
-
-    if(facet_num == -1) {
-      break;
-    }
-
-    if(facet_num == first_facet) {
-      /* back to the beginning */
-      printf("\
-Back to the first facet changing vertices: probably a mobius part.\n\
-Try using a smaller tolerance or don't do a nearby check\n");
-      return;
-    }
-  }
-}
-
-static void
-stl_which_vertices_to_change(stl_file *stl, stl_hash_edge *edge_a,
-                             stl_hash_edge *edge_b, int *facet1, int *vertex1,
-                             int *facet2, int *vertex2,
-                             stl_vertex *new_vertex1, stl_vertex *new_vertex2) {
-  int v1a;			/* pair 1, facet a */
-  int v1b;			/* pair 1, facet b */
-  int v2a;			/* pair 2, facet a */
-  int v2b;			/* pair 2, facet b */
-
-  /* Find first pair */
-  if(edge_a->which_edge < 3) {
-    v1a = edge_a->which_edge;
-    v2a = (edge_a->which_edge + 1) % 3;
-  } else {
-    v2a = edge_a->which_edge % 3;
-    v1a = (edge_a->which_edge + 1) % 3;
-  }
-  if(edge_b->which_edge < 3) {
-    v1b = edge_b->which_edge;
-    v2b = (edge_b->which_edge + 1) % 3;
-  } else {
-    v2b = edge_b->which_edge % 3;
-    v1b = (edge_b->which_edge + 1) % 3;
-  }
-
-  // Of the first pair, which vertex, if any, should be changed
-  if(stl->facet_start[edge_a->facet_number].vertex[v1a] == 
-     stl->facet_start[edge_b->facet_number].vertex[v1b]) {
-    // These facets are already equal.  No need to change.
-    *facet1 = -1;
-  } else {
-    if(   (stl->neighbors_start[edge_a->facet_number].neighbor[v1a] == -1)
-          && (stl->neighbors_start[edge_a->facet_number].
-              neighbor[(v1a + 2) % 3] == -1)) {
-      /* This vertex has no neighbors.  This is a good one to change */
-      *facet1 = edge_a->facet_number;
-      *vertex1 = v1a;
-      *new_vertex1 = stl->facet_start[edge_b->facet_number].vertex[v1b];
-    } else {
-      *facet1 = edge_b->facet_number;
-      *vertex1 = v1b;
-      *new_vertex1 = stl->facet_start[edge_a->facet_number].vertex[v1a];
-    }
-  }
-
-  /* Of the second pair, which vertex, if any, should be changed */
-  if(stl->facet_start[edge_a->facet_number].vertex[v2a] == 
-     stl->facet_start[edge_b->facet_number].vertex[v2b]) {
-    // These facets are already equal.  No need to change.
-    *facet2 = -1;
-  } else {
-    if(   (stl->neighbors_start[edge_a->facet_number].neighbor[v2a] == -1)
-          && (stl->neighbors_start[edge_a->facet_number].
-              neighbor[(v2a + 2) % 3] == -1)) {
-      /* This vertex has no neighbors.  This is a good one to change */
-      *facet2 = edge_a->facet_number;
-      *vertex2 = v2a;
-      *new_vertex2 = stl->facet_start[edge_b->facet_number].vertex[v2b];
-    } else {
-      *facet2 = edge_b->facet_number;
-      *vertex2 = v2b;
-      *new_vertex2 = stl->facet_start[edge_a->facet_number].vertex[v2a];
-    }
-  }
-}
-
-static void
-stl_remove_facet(stl_file *stl, int facet_number) {
-  int neighbor[3];
-  int vnot[3];
-  int i;
-  int j;
-
-  if (stl->error) return;
-
-  stl->stats.facets_removed += 1;
-  /* Update list of connected edges */
-  j = ((stl->neighbors_start[facet_number].neighbor[0] == -1) +
-       (stl->neighbors_start[facet_number].neighbor[1] == -1) +
-       (stl->neighbors_start[facet_number].neighbor[2] == -1));
-  if(j == 2) {
-    stl->stats.connected_facets_1_edge -= 1;
-  } else if(j == 1) {
-    stl->stats.connected_facets_2_edge -= 1;
-    stl->stats.connected_facets_1_edge -= 1;
-  } else if(j == 0) {
-    stl->stats.connected_facets_3_edge -= 1;
-    stl->stats.connected_facets_2_edge -= 1;
-    stl->stats.connected_facets_1_edge -= 1;
-  }
-
-  stl->facet_start[facet_number] =
-    stl->facet_start[stl->stats.number_of_facets - 1];
-  /* I could reallocate at this point, but it is not really necessary. */
-  stl->neighbors_start[facet_number] =
-    stl->neighbors_start[stl->stats.number_of_facets - 1];
-  stl->stats.number_of_facets -= 1;
-
-  for(i = 0; i < 3; i++) {
-    neighbor[i] = stl->neighbors_start[facet_number].neighbor[i];
-    vnot[i] = stl->neighbors_start[facet_number].which_vertex_not[i];
-  }
-
-  for(i = 0; i < 3; i++) {
-    if(neighbor[i] != -1) {
-      if(stl->neighbors_start[neighbor[i]].neighbor[(vnot[i] + 1)% 3] !=
-          stl->stats.number_of_facets) {
-        printf("\
-in stl_remove_facet: neighbor = %d numfacets = %d this is wrong\n",
-               stl->neighbors_start[neighbor[i]].neighbor[(vnot[i] + 1)% 3],
-               stl->stats.number_of_facets);
-        return;
-      }
-      stl->neighbors_start[neighbor[i]].neighbor[(vnot[i] + 1)% 3]
-        = facet_number;
-    }
-  }
+  	HashTableEdges hash_table(stl->stats.number_of_facets);
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+    	//FIXME is the copy necessary?
+    	stl_facet facet = stl->facet_start[i];
+    	for (int j = 0; j < 3; j++) {
+      		if (stl->neighbors_start[i].neighbor[j] == -1) {
+        		HashEdge edge;
+        		edge.facet_number = i;
+        		edge.which_edge = j;
+        		if (edge.load_nearby(stl, facet.vertex[j], facet.vertex[(j + 1) % 3], tolerance))
+          			// Only insert edges that have different keys.
+          			hash_table.insert_edge_nearby(stl, edge);
+      		}
+    	}
+  	}
 }
 
 void stl_remove_unconnected_facets(stl_file *stl)
 {
-  /* A couple of things need to be done here.  One is to remove any */
-  /* completely unconnected facets (0 edges connected) since these are */
-  /* useless and could be completely wrong.   The second thing that needs to */
-  /* be done is to remove any degenerate facets that were created during */
-  /* stl_check_facets_nearby(). */
-  if (stl->error)
-    return;
+	// A couple of things need to be done here.  One is to remove any completely unconnected facets (0 edges connected) since these are
+	// useless and could be completely wrong.   The second thing that needs to be done is to remove any degenerate facets that were created during
+	// stl_check_facets_nearby().
+	auto remove_facet = [stl](int facet_number)
+	{
+		++ stl->stats.facets_removed;
+		/* Update list of connected edges */
+		stl_neighbors &neighbors = stl->neighbors_start[facet_number];
+		// Update statistics on unconnected triangle edges.
+		switch ((neighbors.neighbor[0] == -1) + (neighbors.neighbor[1] == -1) + (neighbors.neighbor[2] == -1)) {
+		case 0: // Facet has 3 neighbors
+			-- stl->stats.connected_facets_3_edge;
+			-- stl->stats.connected_facets_2_edge;
+			-- stl->stats.connected_facets_1_edge;
+			break;
+		case 1: // Facet has 2 neighbors
+			-- stl->stats.connected_facets_2_edge;
+			-- stl->stats.connected_facets_1_edge;
+			break;
+		case 2: // Facet has 1 neighbor
+			-- stl->stats.connected_facets_1_edge;
+		case 3: // Facet has 0 neighbors
+			break;
+		default:
+			assert(false);
+		}
 
-  // remove degenerate facets
-  for (int i = 0; i < stl->stats.number_of_facets; ++ i) {
-    if(stl->facet_start[i].vertex[0] == stl->facet_start[i].vertex[1] ||
-       stl->facet_start[i].vertex[0] == stl->facet_start[i].vertex[2] ||
-       stl->facet_start[i].vertex[1] == stl->facet_start[i].vertex[2]) {
-      stl_remove_degenerate(stl, i);
-      i--;
-    }
-  }
+	  	if (facet_number < -- stl->stats.number_of_facets) {
+	  		// Removing a face, which was not the last one.
+		  	// Copy the face and neighborship from the last face to facet_number.
+		  	stl->facet_start[facet_number] = stl->facet_start[stl->stats.number_of_facets];
+		  	neighbors = stl->neighbors_start[stl->stats.number_of_facets];
+		  	// Update neighborship of faces, which used to point to the last face, now moved to facet_number.
+		  	for (int i = 0; i < 3; ++ i)
+		    	if (neighbors.neighbor[i] != -1) {
+			    	int &other_face_idx = stl->neighbors_start[neighbors.neighbor[i]].neighbor[(neighbors.which_vertex_not[i] + 1) % 3];
+			  		if (other_face_idx != stl->stats.number_of_facets) {
+			  			BOOST_LOG_TRIVIAL(info) << "in remove_facet: neighbor = " << other_face_idx << " numfacets = " << stl->stats.number_of_facets << " this is wrong";
+			    		return;
+			  		}
+			  		other_face_idx = facet_number;
+		  		}
+		}
 
-  if(stl->stats.connected_facets_1_edge < stl->stats.number_of_facets) {
-    // remove completely unconnected facets
-    for (int i = 0; i < stl->stats.number_of_facets; i++) {
-      if (stl->neighbors_start[i].neighbor[0] == -1 &&
-          stl->neighbors_start[i].neighbor[1] == -1 &&
-          stl->neighbors_start[i].neighbor[2] == -1) {
-        // This facet is completely unconnected.  Remove it.
-        stl_remove_facet(stl, i);
-        -- i;
-      }
-    }
-  }
+	  	stl->facet_start.pop_back();
+	  	stl->neighbors_start.pop_back();
+	};
+
+	auto remove_degenerate = [stl, remove_facet](int facet)
+	{
+		// Update statistics on face connectivity.
+		auto stl_update_connects_remove_1 = [stl](int facet_num) {
+			//FIXME when decreasing 3_edge, should I increase 2_edge etc?
+			switch ((stl->neighbors_start[facet_num].neighbor[0] == -1) + (stl->neighbors_start[facet_num].neighbor[1] == -1) + (stl->neighbors_start[facet_num].neighbor[2] == -1)) {
+			case 0: // Facet has 3 neighbors
+				-- stl->stats.connected_facets_3_edge; break;
+			case 1: // Facet has 2 neighbors
+				-- stl->stats.connected_facets_2_edge; break;
+			case 2: // Facet has 1 neighbor
+				-- stl->stats.connected_facets_1_edge; break;
+			case 3: // Facet has 0 neighbors
+				break;
+			default:
+				assert(false);
+		  	}
+		};
+
+		int edge_to_collapse = 0;
+	   	if (stl->facet_start[facet].vertex[0] == stl->facet_start[facet].vertex[1]) {
+			if (stl->facet_start[facet].vertex[1] == stl->facet_start[facet].vertex[2]) {
+				// All 3 vertices are equal. Collapse the edge with no neighbor if it exists.
+				const int *nbr = stl->neighbors_start[facet].neighbor;
+				edge_to_collapse = (nbr[0] == -1) ? 0 : (nbr[1] == -1) ? 1 : 2;
+			} else {
+				edge_to_collapse = 0;
+			}
+	  	} else if (stl->facet_start[facet].vertex[1] == stl->facet_start[facet].vertex[2]) {
+			edge_to_collapse = 1;
+	  	} else if (stl->facet_start[facet].vertex[2] == stl->facet_start[facet].vertex[0]) {
+			edge_to_collapse = 2;
+	  	} else {
+	    	// No degenerate. Function shouldn't have been called.
+	    	return;
+	  	}
+
+		int edge[3] = { (edge_to_collapse + 1) % 3, (edge_to_collapse + 2) % 3, edge_to_collapse };
+		int neighbor[] = {
+			stl->neighbors_start[facet].neighbor[edge[0]],
+			stl->neighbors_start[facet].neighbor[edge[1]],
+			stl->neighbors_start[facet].neighbor[edge[2]]
+		};
+		int vnot[] = {
+			stl->neighbors_start[facet].which_vertex_not[edge[0]],
+			stl->neighbors_start[facet].which_vertex_not[edge[1]],
+			stl->neighbors_start[facet].which_vertex_not[edge[2]]
+		};
+		// Update statistics on edge connectivity.
+	  	if (neighbor[0] == -1)
+	    	stl_update_connects_remove_1(neighbor[1]);
+	  	if (neighbor[1] == -1)
+	    	stl_update_connects_remove_1(neighbor[0]);
+
+	  	if (neighbor[0] >= 0) {
+			if (neighbor[1] >= 0) {
+				// Adjust the "flip" flag for the which_vertex_not values.
+				if (vnot[0] > 2) {
+					if (vnot[1] > 2) {
+						// The face to be removed has its normal flipped compared to the left & right neighbors, therefore after removing this face
+						// the two remaining neighbors will be oriented correctly.
+						vnot[0] -= 3;
+						vnot[1] -= 3;
+					} else
+						// One neighbor has its normal inverted compared to the face to be removed, the other is oriented equally.
+						// After removal, the two neighbors will have their normals flipped.
+						vnot[1] += 3;
+				} else if (vnot[1] > 2)
+					// One neighbor has its normal inverted compared to the face to be removed, the other is oriented equally.
+					// After removal, the two neighbors will have their normals flipped.
+					vnot[0] += 3;
+			}
+			stl->neighbors_start[neighbor[0]].neighbor[(vnot[0] + 1) % 3] = (neighbor[0] == neighbor[1]) ? -1 : neighbor[1];
+	    	stl->neighbors_start[neighbor[0]].which_vertex_not[(vnot[0] + 1) % 3] = vnot[1];
+	  	}
+	  	if (neighbor[1] >= 0) {
+			stl->neighbors_start[neighbor[1]].neighbor[(vnot[1] + 1) % 3] = (neighbor[0] == neighbor[1]) ? -1 : neighbor[0];
+	    	stl->neighbors_start[neighbor[1]].which_vertex_not[(vnot[1] + 1) % 3] = vnot[0];
+	  	}
+		if (neighbor[2] >= 0) {
+			stl_update_connects_remove_1(neighbor[2]);
+			stl->neighbors_start[neighbor[2]].neighbor[(vnot[2] + 1) % 3] = -1;
+		}
+
+	  	remove_facet(facet);
+	};
+
+	// remove degenerate facets
+	for (uint32_t i = 0; i < stl->stats.number_of_facets;)
+		if (stl->facet_start[i].vertex[0] == stl->facet_start[i].vertex[1] ||
+			stl->facet_start[i].vertex[0] == stl->facet_start[i].vertex[2] ||
+			stl->facet_start[i].vertex[1] == stl->facet_start[i].vertex[2]) {
+			remove_degenerate(i);
+//			assert(stl_validate(stl));
+		} else
+			++ i;
+
+	if (stl->stats.connected_facets_1_edge < (int)stl->stats.number_of_facets) {
+		// remove completely unconnected facets
+		for (uint32_t i = 0; i < stl->stats.number_of_facets;)
+			if (stl->neighbors_start[i].neighbor[0] == -1 &&
+				stl->neighbors_start[i].neighbor[1] == -1 &&
+				stl->neighbors_start[i].neighbor[2] == -1) {
+				// This facet is completely unconnected.  Remove it.
+				remove_facet(i);
+				assert(stl_validate(stl));
+			} else
+				++ i;
+	}
 }
 
-static void
-stl_remove_degenerate(stl_file *stl, int facet) {
-  int edge1;
-  int edge2;
-  int edge3;
-  int neighbor1;
-  int neighbor2;
-  int neighbor3;
-  int vnot1;
-  int vnot2;
-  int vnot3;
+void stl_fill_holes(stl_file *stl)
+{
+	// Insert all unconnected edges into hash list.
+	HashTableEdges hash_table(stl->stats.number_of_facets);
+	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+  		stl_facet facet = stl->facet_start[i];
+		for (int j = 0; j < 3; ++ j) {
+	  		if(stl->neighbors_start[i].neighbor[j] != -1)
+	  			continue;
+			HashEdge edge;
+	  		edge.facet_number = i;
+	  		edge.which_edge = j;
+	  		edge.load_exact(stl, &facet.vertex[j], &facet.vertex[(j + 1) % 3]);
+	  		hash_table.insert_edge_exact(stl, edge);
+		}
+	}
 
-  if (stl->error) return;
+	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+		stl_facet facet = stl->facet_start[i];
+		int neighbors_initial[3] = { stl->neighbors_start[i].neighbor[0], stl->neighbors_start[i].neighbor[1], stl->neighbors_start[i].neighbor[2] };
+		int first_facet = i;
+		for (int j = 0; j < 3; ++ j) {
+	  		if (stl->neighbors_start[i].neighbor[j] != -1)
+	  			continue;
 
-  if (stl->facet_start[facet].vertex[0] == stl->facet_start[facet].vertex[1] &&
-      stl->facet_start[facet].vertex[1] == stl->facet_start[facet].vertex[2]) {
-    /* all 3 vertices are equal.  Just remove the facet.  I don't think*/
-    /* this is really possible, but just in case... */
-    printf("removing a facet in stl_remove_degenerate\n");
-    stl_remove_facet(stl, facet);
-    return;
-  }
+  			stl_facet new_facet;
+	  		new_facet.vertex[0] = facet.vertex[j];
+	  		new_facet.vertex[1] = facet.vertex[(j + 1) % 3];
+		  	bool direction = neighbors_initial[(j + 2) % 3] == -1;
+  			int facet_num = i;
+		  	int vnot = (j + 2) % 3;
 
-  if (stl->facet_start[facet].vertex[0] == stl->facet_start[facet].vertex[1]) {
-    edge1 = 1;
-    edge2 = 2;
-    edge3 = 0;
-  } else if (stl->facet_start[facet].vertex[1] == stl->facet_start[facet].vertex[2]) {
-    edge1 = 0;
-    edge2 = 2;
-    edge3 = 1;
-  } else if (stl->facet_start[facet].vertex[2] == stl->facet_start[facet].vertex[0]) {
-    edge1 = 0;
-    edge2 = 1;
-    edge3 = 2;
-  } else {
-    /* No degenerate. Function shouldn't have been called. */
-    return;
-  }
-  neighbor1 = stl->neighbors_start[facet].neighbor[edge1];
-  neighbor2 = stl->neighbors_start[facet].neighbor[edge2];
+	  		for (;;) {
+				int pivot_vertex = 0;
+				int next_edge = 0;
+	    		if (vnot > 2) {
+	      			if (direction) {
+	        			pivot_vertex = (vnot + 1) % 3;
+	        			next_edge = vnot % 3;
+	      			} else {
+	        			pivot_vertex = (vnot + 2) % 3;
+	        			next_edge = pivot_vertex;
+	      			}
+	      			direction = ! direction;
+	    		} else {
+	      			if(direction == 0) {
+	        			pivot_vertex = (vnot + 1) % 3;
+	        			next_edge = vnot;
+	      			} else {
+	        			pivot_vertex = (vnot + 2) % 3;
+	        			next_edge = pivot_vertex;
+	      			}
+	    		}
 
-  if(neighbor1 == -1) {
-    stl_update_connects_remove_1(stl, neighbor2);
-  }
-  if(neighbor2 == -1) {
-    stl_update_connects_remove_1(stl, neighbor1);
-  }
+	    		int next_facet = stl->neighbors_start[facet_num].neighbor[next_edge];
+	    		if (next_facet == -1) {
+	      			new_facet.vertex[2] = stl->facet_start[facet_num].vertex[vnot % 3];
+				    stl_add_facet(stl, &new_facet);
+	      			for (int k = 0; k < 3; ++ k) {
+	      				HashEdge edge;
+	        			edge.facet_number = stl->stats.number_of_facets - 1;
+	        			edge.which_edge = k;
+	        			edge.load_exact(stl, &new_facet.vertex[k], &new_facet.vertex[(k + 1) % 3]);
+	        			hash_table.insert_edge_exact(stl, edge);
+	      			}
+	      			break;
+	    		}
 
+	      		vnot = stl->neighbors_start[facet_num].which_vertex_not[next_edge];
+	      		facet_num = next_facet;
 
-  neighbor3 = stl->neighbors_start[facet].neighbor[edge3];
-  vnot1 = stl->neighbors_start[facet].which_vertex_not[edge1];
-  vnot2 = stl->neighbors_start[facet].which_vertex_not[edge2];
-  vnot3 = stl->neighbors_start[facet].which_vertex_not[edge3];
-
-  if(neighbor1 >= 0){
-    stl->neighbors_start[neighbor1].neighbor[(vnot1 + 1) % 3] = neighbor2;
-    stl->neighbors_start[neighbor1].which_vertex_not[(vnot1 + 1) % 3] = vnot2;
-  }
-  if(neighbor2 >= 0){
-    stl->neighbors_start[neighbor2].neighbor[(vnot2 + 1) % 3] = neighbor1;
-    stl->neighbors_start[neighbor2].which_vertex_not[(vnot2 + 1) % 3] = vnot1;
-  }
-
-  stl_remove_facet(stl, facet);
-
-  if(neighbor3 >= 0) {
-    stl_update_connects_remove_1(stl, neighbor3);
-    stl->neighbors_start[neighbor3].neighbor[(vnot3 + 1) % 3] = -1;
-  }
+	    		if (facet_num == first_facet) {
+	      			// back to the beginning
+		  			BOOST_LOG_TRIVIAL(info) << "Back to the first facet filling holes: probably a mobius part. Try using a smaller tolerance or don't do a nearby check.";
+	      			return;
+	    		}
+	  		}
+		}
+	}
 }
 
-void
-stl_update_connects_remove_1(stl_file *stl, int facet_num) {
-  int j;
-
-  if (stl->error) return;
-  /* Update list of connected edges */
-  j = ((stl->neighbors_start[facet_num].neighbor[0] == -1) +
-       (stl->neighbors_start[facet_num].neighbor[1] == -1) +
-       (stl->neighbors_start[facet_num].neighbor[2] == -1));
-  if(j == 0) {		       /* Facet has 3 neighbors */
-    stl->stats.connected_facets_3_edge -= 1;
-  } else if(j == 1) {	     /* Facet has 2 neighbors */
-    stl->stats.connected_facets_2_edge -= 1;
-  } else if(j == 2) {	     /* Facet has 1 neighbor  */
-    stl->stats.connected_facets_1_edge -= 1;
-  }
-}
-
-void
-stl_fill_holes(stl_file *stl) {
-  stl_facet facet;
-  stl_facet new_facet;
-  int neighbors_initial[3];
-  stl_hash_edge edge;
-  int first_facet;
-  int direction;
-  int facet_num;
-  int vnot;
-  int next_edge;
-  int pivot_vertex;
-  int next_facet;
-  int i;
-  int j;
-  int k;
-
-  if (stl->error) return;
-
-  /* Insert all unconnected edges into hash list */
-  stl_initialize_facet_check_nearby(stl);
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    facet = stl->facet_start[i];
-    for(j = 0; j < 3; j++) {
-      if(stl->neighbors_start[i].neighbor[j] != -1) continue;
-      edge.facet_number = i;
-      edge.which_edge = j;
-      stl_load_edge_exact(stl, &edge, &facet.vertex[j],
-                          &facet.vertex[(j + 1) % 3]);
-
-      insert_hash_edge(stl, edge, stl_record_neighbors);
-    }
-  }
-
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    facet = stl->facet_start[i];
-    neighbors_initial[0] = stl->neighbors_start[i].neighbor[0];
-    neighbors_initial[1] = stl->neighbors_start[i].neighbor[1];
-    neighbors_initial[2] = stl->neighbors_start[i].neighbor[2];
-    first_facet = i;
-    for(j = 0; j < 3; j++) {
-      if(stl->neighbors_start[i].neighbor[j] != -1) continue;
-
-      new_facet.vertex[0] = facet.vertex[j];
-      new_facet.vertex[1] = facet.vertex[(j + 1) % 3];
-      if(neighbors_initial[(j + 2) % 3] == -1) {
-        direction = 1;
-      } else {
-        direction = 0;
-      }
-
-      facet_num = i;
-      vnot = (j + 2) % 3;
-
-      for(;;) {
-        if(vnot > 2) {
-          if(direction == 0) {
-            pivot_vertex = (vnot + 2) % 3;
-            next_edge = pivot_vertex;
-            direction = 1;
-          } else {
-            pivot_vertex = (vnot + 1) % 3;
-            next_edge = vnot % 3;
-            direction = 0;
-          }
-        } else {
-          if(direction == 0) {
-            pivot_vertex = (vnot + 1) % 3;
-            next_edge = vnot;
-          } else {
-            pivot_vertex = (vnot + 2) % 3;
-            next_edge = pivot_vertex;
-          }
-        }
-        next_facet = stl->neighbors_start[facet_num].neighbor[next_edge];
-
-        if(next_facet == -1) {
-          new_facet.vertex[2] = stl->facet_start[facet_num].
-                                vertex[vnot % 3];
-          stl_add_facet(stl, &new_facet);
-          for(k = 0; k < 3; k++) {
-            edge.facet_number = stl->stats.number_of_facets - 1;
-            edge.which_edge = k;
-            stl_load_edge_exact(stl, &edge, &new_facet.vertex[k],
-                                &new_facet.vertex[(k + 1) % 3]);
-
-            insert_hash_edge(stl, edge, stl_record_neighbors);
-          }
-          break;
-        } else {
-          vnot = stl->neighbors_start[facet_num].
-                 which_vertex_not[next_edge];
-          facet_num = next_facet;
-        }
-
-        if(facet_num == first_facet) {
-          /* back to the beginning */
-          printf("\
-Back to the first facet filling holes: probably a mobius part.\n\
-Try using a smaller tolerance or don't do a nearby check\n");
-          return;
-        }
-      }
-    }
-  }
-}
-
-void
-stl_add_facet(stl_file *stl, stl_facet *new_facet) {
-  if (stl->error) return;
-
-  stl->stats.facets_added += 1;
-  if(stl->stats.facets_malloced < stl->stats.number_of_facets + 1) {
-    stl->facet_start = (stl_facet*)realloc(stl->facet_start,
-                                           (sizeof(stl_facet) * (stl->stats.facets_malloced + 256)));
-    if(stl->facet_start == NULL) perror("stl_add_facet");
-    stl->neighbors_start = (stl_neighbors*)realloc(stl->neighbors_start,
-                           (sizeof(stl_neighbors) * (stl->stats.facets_malloced + 256)));
-    if(stl->neighbors_start == NULL) perror("stl_add_facet");
-    stl->stats.facets_malloced += 256;
-  }
-  stl->facet_start[stl->stats.number_of_facets] = *new_facet;
-
-  /* note that the normal vector is not set here, just initialized to 0 */
-  stl->facet_start[stl->stats.number_of_facets].normal = stl_normal::Zero();
-
-  stl->neighbors_start[stl->stats.number_of_facets].neighbor[0] = -1;
-  stl->neighbors_start[stl->stats.number_of_facets].neighbor[1] = -1;
-  stl->neighbors_start[stl->stats.number_of_facets].neighbor[2] = -1;
-  stl->stats.number_of_facets += 1;
+void stl_add_facet(stl_file *stl, const stl_facet *new_facet)
+{
+	assert(stl->facet_start.size() == stl->stats.number_of_facets);
+	assert(stl->neighbors_start.size() == stl->stats.number_of_facets);
+	stl->facet_start.emplace_back(*new_facet);
+  	// note that the normal vector is not set here, just initialized to 0.
+  	stl->facet_start[stl->stats.number_of_facets].normal = stl_normal::Zero();
+  	stl->neighbors_start.emplace_back();
+	++ stl->stats.facets_added;
+	++ stl->stats.number_of_facets;
 }
diff --git a/src/admesh/normals.cpp b/src/admesh/normals.cpp
index ecf08b59c..16bb3daab 100644
--- a/src/admesh/normals.cpp
+++ b/src/admesh/normals.cpp
@@ -25,271 +25,214 @@
 #include <string.h>
 #include <math.h>
 
+// Boost pool: Don't use mutexes to synchronize memory allocation.
+#define BOOST_POOL_NO_MT
+#include <boost/pool/object_pool.hpp>
+
 #include "stl.h"
 
-static int stl_check_normal_vector(stl_file *stl, int facet_num, int normal_fix_flag);
+static void reverse_facet(stl_file *stl, int facet_num)
+{
+	++ stl->stats.facets_reversed;
 
-static void
-stl_reverse_facet(stl_file *stl, int facet_num) {
-  stl_vertex tmp_vertex;
-  /*  int tmp_neighbor;*/
-  int neighbor[3];
-  int vnot[3];
+	int neighbor[3] = { stl->neighbors_start[facet_num].neighbor[0], stl->neighbors_start[facet_num].neighbor[1], stl->neighbors_start[facet_num].neighbor[2] };
+	int vnot[3] = { stl->neighbors_start[facet_num].which_vertex_not[0], stl->neighbors_start[facet_num].which_vertex_not[1], stl->neighbors_start[facet_num].which_vertex_not[2] };
 
-  stl->stats.facets_reversed += 1;
+	// reverse the facet
+	stl_vertex tmp_vertex = stl->facet_start[facet_num].vertex[0];
+	stl->facet_start[facet_num].vertex[0] = stl->facet_start[facet_num].vertex[1];
+	stl->facet_start[facet_num].vertex[1] = tmp_vertex;
 
-  neighbor[0] = stl->neighbors_start[facet_num].neighbor[0];
-  neighbor[1] = stl->neighbors_start[facet_num].neighbor[1];
-  neighbor[2] = stl->neighbors_start[facet_num].neighbor[2];
-  vnot[0] = stl->neighbors_start[facet_num].which_vertex_not[0];
-  vnot[1] = stl->neighbors_start[facet_num].which_vertex_not[1];
-  vnot[2] = stl->neighbors_start[facet_num].which_vertex_not[2];
+	// fix the vnots of the neighboring facets
+	if (neighbor[0] != -1)
+		stl->neighbors_start[neighbor[0]].which_vertex_not[(vnot[0] + 1) % 3] = (stl->neighbors_start[neighbor[0]].which_vertex_not[(vnot[0] + 1) % 3] + 3) % 6;
+	if (neighbor[1] != -1)
+		stl->neighbors_start[neighbor[1]].which_vertex_not[(vnot[1] + 1) % 3] = (stl->neighbors_start[neighbor[1]].which_vertex_not[(vnot[1] + 1) % 3] + 4) % 6;
+	if (neighbor[2] != -1)
+		stl->neighbors_start[neighbor[2]].which_vertex_not[(vnot[2] + 1) % 3] = (stl->neighbors_start[neighbor[2]].which_vertex_not[(vnot[2] + 1) % 3] + 2) % 6;
 
-  /* reverse the facet */
-  tmp_vertex = stl->facet_start[facet_num].vertex[0];
-  stl->facet_start[facet_num].vertex[0] =
-    stl->facet_start[facet_num].vertex[1];
-  stl->facet_start[facet_num].vertex[1] = tmp_vertex;
+	// swap the neighbors of the facet that is being reversed
+	stl->neighbors_start[facet_num].neighbor[1] = neighbor[2];
+	stl->neighbors_start[facet_num].neighbor[2] = neighbor[1];
 
-  /* fix the vnots of the neighboring facets */
-  if(neighbor[0] != -1)
-    stl->neighbors_start[neighbor[0]].which_vertex_not[(vnot[0] + 1) % 3] =
-      (stl->neighbors_start[neighbor[0]].
-       which_vertex_not[(vnot[0] + 1) % 3] + 3) % 6;
-  if(neighbor[1] != -1)
-    stl->neighbors_start[neighbor[1]].which_vertex_not[(vnot[1] + 1) % 3] =
-      (stl->neighbors_start[neighbor[1]].
-       which_vertex_not[(vnot[1] + 1) % 3] + 4) % 6;
-  if(neighbor[2] != -1)
-    stl->neighbors_start[neighbor[2]].which_vertex_not[(vnot[2] + 1) % 3] =
-      (stl->neighbors_start[neighbor[2]].
-       which_vertex_not[(vnot[2] + 1) % 3] + 2) % 6;
+	// swap the vnots of the facet that is being reversed 
+	stl->neighbors_start[facet_num].which_vertex_not[1] = vnot[2];
+	stl->neighbors_start[facet_num].which_vertex_not[2] = vnot[1];
 
-  /* swap the neighbors of the facet that is being reversed */
-  stl->neighbors_start[facet_num].neighbor[1] = neighbor[2];
-  stl->neighbors_start[facet_num].neighbor[2] = neighbor[1];
-
-  /* swap the vnots of the facet that is being reversed */
-  stl->neighbors_start[facet_num].which_vertex_not[1] = vnot[2];
-  stl->neighbors_start[facet_num].which_vertex_not[2] = vnot[1];
-
-  /* reverse the values of the vnots of the facet that is being reversed */
-  stl->neighbors_start[facet_num].which_vertex_not[0] =
-    (stl->neighbors_start[facet_num].which_vertex_not[0] + 3) % 6;
-  stl->neighbors_start[facet_num].which_vertex_not[1] =
-    (stl->neighbors_start[facet_num].which_vertex_not[1] + 3) % 6;
-  stl->neighbors_start[facet_num].which_vertex_not[2] =
-    (stl->neighbors_start[facet_num].which_vertex_not[2] + 3) % 6;
+	// reverse the values of the vnots of the facet that is being reversed
+	stl->neighbors_start[facet_num].which_vertex_not[0] = (stl->neighbors_start[facet_num].which_vertex_not[0] + 3) % 6;
+	stl->neighbors_start[facet_num].which_vertex_not[1] = (stl->neighbors_start[facet_num].which_vertex_not[1] + 3) % 6;
+	stl->neighbors_start[facet_num].which_vertex_not[2] = (stl->neighbors_start[facet_num].which_vertex_not[2] + 3) % 6;
 }
 
-void
-stl_fix_normal_directions(stl_file *stl) {
-  char *norm_sw;
-  /*  int edge_num;*/
-  /*  int vnot;*/
-  int checked = 0;
-  int facet_num;
-  /*  int next_facet;*/
-  int i;
-  int j;
-  struct stl_normal {
-    int               facet_num;
-    struct stl_normal *next;
-  };
-  struct stl_normal *head;
-  struct stl_normal *tail;
-  struct stl_normal *newn;
-  struct stl_normal *temp;
+// Returns true if the normal was flipped.
+static bool check_normal_vector(stl_file *stl, int facet_num, int normal_fix_flag)
+{
+	stl_facet *facet = &stl->facet_start[facet_num];
 
-  int* reversed_ids;
-  int reversed_count = 0;
-  int id;
-  int force_exit = 0;
+	stl_normal normal;
+	stl_calculate_normal(normal, facet);
+	stl_normalize_vector(normal);
+	stl_normal normal_dif = (normal - facet->normal).cwiseAbs();
 
-  if (stl->error) return;
+	const float eps = 0.001f;
+	if (normal_dif(0) < eps && normal_dif(1) < eps && normal_dif(2) < eps) {
+		// Normal is within tolerance. It is not really necessary to change the values here, but just for consistency, I will.
+		facet->normal = normal;
+		return false;
+	}
 
-  // this may happen for malformed models, see: https://github.com/prusa3d/PrusaSlicer/issues/2209
-  if (stl->stats.number_of_facets == 0) return;
+	stl_normal test_norm = facet->normal;
+	stl_normalize_vector(test_norm);
+	normal_dif = (normal - test_norm).cwiseAbs();
+	if (normal_dif(0) < eps && normal_dif(1) < eps && normal_dif(2) < eps) {
+		// The normal is not within tolerance, but direction is OK.
+		if (normal_fix_flag) {
+	  		facet->normal = normal;
+	  		++ stl->stats.normals_fixed;
+		}
+		return false;
+	}
 
-  /* Initialize linked list. */
-  head = (struct stl_normal*)malloc(sizeof(struct stl_normal));
-  if(head == NULL) perror("stl_fix_normal_directions");
-  tail = (struct stl_normal*)malloc(sizeof(struct stl_normal));
-  if(tail == NULL) perror("stl_fix_normal_directions");
-  head->next = tail;
-  tail->next = tail;
-
-  /* Initialize list that keeps track of already fixed facets. */
-  norm_sw = (char*)calloc(stl->stats.number_of_facets, sizeof(char));
-  if(norm_sw == NULL) perror("stl_fix_normal_directions");
-
-  /* Initialize list that keeps track of reversed facets. */
-  reversed_ids = (int*)calloc(stl->stats.number_of_facets, sizeof(int));
-  if (reversed_ids == NULL) perror("stl_fix_normal_directions reversed_ids");
-
-  facet_num = 0;
-  /* If normal vector is not within tolerance and backwards:
-     Arbitrarily starts at face 0.  If this one is wrong, we're screwed.  Thankfully, the chances
-     of it being wrong randomly are low if most of the triangles are right: */
-  if (stl_check_normal_vector(stl, 0, 0) == 2) {
-      stl_reverse_facet(stl, 0);
-      reversed_ids[reversed_count++] = 0;
-  }
-
-  /* Say that we've fixed this facet: */
-  norm_sw[facet_num] = 1;
-  checked++;
-
-  for(;;) {
-    /* Add neighbors_to_list.
-       Add unconnected neighbors to the list:a  */
-    for(j = 0; j < 3; j++) {
-      /* Reverse the neighboring facets if necessary. */
-      if(stl->neighbors_start[facet_num].which_vertex_not[j] > 2) {
-        /* If the facet has a neighbor that is -1, it means that edge isn't shared by another facet */
-        if(stl->neighbors_start[facet_num].neighbor[j] != -1) {
-            if (norm_sw[stl->neighbors_start[facet_num].neighbor[j]] == 1) {
-                /* trying to modify a facet already marked as fixed, revert all changes made until now and exit (fixes: #716, #574, #413, #269, #262, #259, #230, #228, #206) */
-                for (id = reversed_count - 1; id >= 0; --id) {
-                    stl_reverse_facet(stl, reversed_ids[id]);
-                }
-                force_exit = 1;
-                break;
-            } else {
-                stl_reverse_facet(stl, stl->neighbors_start[facet_num].neighbor[j]);
-                reversed_ids[reversed_count++] = stl->neighbors_start[facet_num].neighbor[j];
-            }
-        }
-      }
-      /* If this edge of the facet is connected: */
-      if(stl->neighbors_start[facet_num].neighbor[j] != -1) {
-        /* If we haven't fixed this facet yet, add it to the list: */
-        if(norm_sw[stl->neighbors_start[facet_num].neighbor[j]] != 1) {
-          /* Add node to beginning of list. */
-          newn = (struct stl_normal*)malloc(sizeof(struct stl_normal));
-          if(newn == NULL) perror("stl_fix_normal_directions");
-          newn->facet_num = stl->neighbors_start[facet_num].neighbor[j];
-          newn->next = head->next;
-          head->next = newn;
-        }
-      }
-    }
-
-    /* an error occourred, quit the for loop and exit */
-    if (force_exit) break;
-
-    /* Get next facet to fix from top of list. */
-    if(head->next != tail) {
-      facet_num = head->next->facet_num;
-      if(norm_sw[facet_num] != 1) { /* If facet is in list mutiple times */
-        norm_sw[facet_num] = 1; /* Record this one as being fixed. */
-        checked++;
-      }
-      temp = head->next;	/* Delete this facet from the list. */
-      head->next = head->next->next;
-      free(temp);
-    } else { /* if we ran out of facets to fix: */
-      /* All of the facets in this part have been fixed. */
-      stl->stats.number_of_parts += 1;
-      if(checked >= stl->stats.number_of_facets) {
-        /* All of the facets have been checked.  Bail out. */
-        break;
-      } else {
-        /* There is another part here.  Find it and continue. */
-        for(i = 0; i < stl->stats.number_of_facets; i++) {
-          if(norm_sw[i] == 0) {
-            /* This is the first facet of the next part. */
-            facet_num = i;
-            if(stl_check_normal_vector(stl, i, 0) == 2) {
-                stl_reverse_facet(stl, i);
-                reversed_ids[reversed_count++] = i;
-            }
-
-            norm_sw[facet_num] = 1;
-            checked++;
-            break;
-          }
-        }
-      }
-    }
-  }
-  free(head);
-  free(tail);
-  free(reversed_ids);
-  free(norm_sw);
+	test_norm *= -1.f;
+	normal_dif = (normal - test_norm).cwiseAbs();
+	if (normal_dif(0) < eps && normal_dif(1) < eps && normal_dif(2) < eps) {
+		// The normal is not within tolerance and backwards.
+		if (normal_fix_flag) {
+	  		facet->normal = normal;
+	  		++ stl->stats.normals_fixed;
+		}
+		return true;
+	}
+	if (normal_fix_flag) {
+		facet->normal = normal;
+		++ stl->stats.normals_fixed;
+	}
+	// Status is unknown.
+	return false;
 }
 
-static int stl_check_normal_vector(stl_file *stl, int facet_num, int normal_fix_flag) {
-  /* Returns 0 if the normal is within tolerance */
-  /* Returns 1 if the normal is not within tolerance, but direction is OK */
-  /* Returns 2 if the normal is not within tolerance and backwards */
-  /* Returns 4 if the status is unknown. */
+void stl_fix_normal_directions(stl_file *stl)
+{
+ 	// This may happen for malformed models, see: https://github.com/prusa3d/PrusaSlicer/issues/2209
+  	if (stl->stats.number_of_facets == 0)
+  		return;
 
-  stl_facet *facet;
+	struct stl_normal {
+    	int         facet_num;
+    	stl_normal *next;
+  	};
 
-  facet = &stl->facet_start[facet_num];
+  	// Initialize linked list.
+  	boost::object_pool<stl_normal> pool;
+   	stl_normal *head = pool.construct();
+  	stl_normal *tail = pool.construct();
+	head->next = tail;
+	tail->next = tail;
 
-  stl_normal normal;
-  stl_calculate_normal(normal, facet);
-  stl_normalize_vector(normal);
-  stl_normal normal_dif = (normal - facet->normal).cwiseAbs();
+	// Initialize list that keeps track of already fixed facets.
+	std::vector<char> norm_sw(stl->stats.number_of_facets, 0);
+	// Initialize list that keeps track of reversed facets.
+	std::vector<int>  reversed_ids(stl->stats.number_of_facets, 0);
 
-  const float eps = 0.001f;
-  if (normal_dif(0) < eps && normal_dif(1) < eps && normal_dif(2) < eps) {
-    /* It is not really necessary to change the values here */
-    /* but just for consistency, I will. */
-    facet->normal = normal;
-    return 0;
-  }
+  	int facet_num = 0;
+  	int reversed_count = 0;
+  	// If normal vector is not within tolerance and backwards:
+    // Arbitrarily starts at face 0.  If this one is wrong, we're screwed. Thankfully, the chances
+    // of it being wrong randomly are low if most of the triangles are right:
+  	if (check_normal_vector(stl, 0, 0)) {
+    	reverse_facet(stl, 0);
+      	reversed_ids[reversed_count ++] = 0;
+  	}
 
-  stl_normal test_norm = facet->normal;
-  stl_normalize_vector(test_norm);
-  normal_dif = (normal - test_norm).cwiseAbs();
-  if (normal_dif(0) < eps && normal_dif(1) < eps && normal_dif(2) < eps) {
-    if(normal_fix_flag) {
-      facet->normal = normal;
-      stl->stats.normals_fixed += 1;
-    }
-    return 1;
-  }
+  	// Say that we've fixed this facet:
+  	norm_sw[facet_num] = 1;
+	int checked = 1;
 
-  test_norm *= -1.f;
-  normal_dif = (normal - test_norm).cwiseAbs();
-  if (normal_dif(0) < eps && normal_dif(1) < eps && normal_dif(2) < eps) {
-    // Facet is backwards.
-    if(normal_fix_flag) {
-      facet->normal = normal;
-      stl->stats.normals_fixed += 1;
-    }
-    return 2;
-  }
-  if(normal_fix_flag) {
-    facet->normal = normal;
-    stl->stats.normals_fixed += 1;
-  }
-  return 4;
+  	for (;;) {
+    	// Add neighbors_to_list. Add unconnected neighbors to the list.
+    	bool force_exit = false;
+    	for (int j = 0; j < 3; ++ j) {
+      		// Reverse the neighboring facets if necessary.
+      		if (stl->neighbors_start[facet_num].which_vertex_not[j] > 2) {
+        		// If the facet has a neighbor that is -1, it means that edge isn't shared by another facet
+        		if (stl->neighbors_start[facet_num].neighbor[j] != -1) {
+            		if (norm_sw[stl->neighbors_start[facet_num].neighbor[j]] == 1) {
+                		// trying to modify a facet already marked as fixed, revert all changes made until now and exit (fixes: #716, #574, #413, #269, #262, #259, #230, #228, #206)
+                		for (int id = reversed_count - 1; id >= 0; -- id)
+                    		reverse_facet(stl, reversed_ids[id]);
+                		force_exit = true;
+                		break;
+            		}
+            		reverse_facet(stl, stl->neighbors_start[facet_num].neighbor[j]);
+            		reversed_ids[reversed_count ++] = stl->neighbors_start[facet_num].neighbor[j];
+        		}
+      		}
+      		// If this edge of the facet is connected:
+      		if (stl->neighbors_start[facet_num].neighbor[j] != -1) {
+        		// If we haven't fixed this facet yet, add it to the list:
+        		if (norm_sw[stl->neighbors_start[facet_num].neighbor[j]] != 1) {
+	          		// Add node to beginning of list.
+	          		stl_normal *newn = pool.construct();
+	          		newn->facet_num = stl->neighbors_start[facet_num].neighbor[j];
+	          		newn->next = head->next;
+	          		head->next = newn;
+	        	}
+	      	}
+	    }
+
+    	// an error occourred, quit the for loop and exit
+    	if (force_exit)
+    		break;
+
+    	// Get next facet to fix from top of list.
+    	if (head->next != tail) {
+      		facet_num = head->next->facet_num;
+      		if (norm_sw[facet_num] != 1) { // If facet is in list mutiple times
+        		norm_sw[facet_num] = 1; // Record this one as being fixed.
+        		++ checked;
+      		}
+      		stl_normal *temp = head->next;	// Delete this facet from the list.
+      		head->next = head->next->next;
+      		// pool.destroy(temp);
+    	} else { // If we ran out of facets to fix: All of the facets in this part have been fixed.
+      		++ stl->stats.number_of_parts;
+      		if (checked >= stl->stats.number_of_facets)
+        		// All of the facets have been checked.  Bail out.
+        		break;
+    		// There is another part here.  Find it and continue.
+    		for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i)
+      			if (norm_sw[i] == 0) {
+        			// This is the first facet of the next part.
+        			facet_num = i;
+        			if (check_normal_vector(stl, i, 0)) {
+            			reverse_facet(stl, i);
+            			reversed_ids[reversed_count++] = i;
+        			}
+        			norm_sw[facet_num] = 1;
+        			++ checked;
+        			break;
+      			}
+    	}
+  	}
+
+	// pool.destroy(head);
+	// pool.destroy(tail);
 }
 
-void stl_fix_normal_values(stl_file *stl) {
-  int i;
-
-  if (stl->error) return;
-
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    stl_check_normal_vector(stl, i, 1);
-  }
+void stl_fix_normal_values(stl_file *stl)
+{
+	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i)
+    	check_normal_vector(stl, i, 1);
 }
 
 void stl_reverse_all_facets(stl_file *stl)
 {
-  if (stl->error)
-  	return;
-
-  stl_normal normal;
-  for(int i = 0; i < stl->stats.number_of_facets; i++) {
-    stl_reverse_facet(stl, i);
-    stl_calculate_normal(normal, &stl->facet_start[i]);
-    stl_normalize_vector(normal);
-    stl->facet_start[i].normal = normal;
-  }
+	stl_normal normal;
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+    	reverse_facet(stl, i);
+    	stl_calculate_normal(normal, &stl->facet_start[i]);
+    	stl_normalize_vector(normal);
+    	stl->facet_start[i].normal = normal;
+  	}
 }
diff --git a/src/admesh/shared.cpp b/src/admesh/shared.cpp
index c8c17ccd5..902bbfc9b 100644
--- a/src/admesh/shared.cpp
+++ b/src/admesh/shared.cpp
@@ -23,242 +23,237 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <vector>
+
+#include <boost/log/trivial.hpp>
 #include <boost/nowide/cstdio.hpp>
 
 #include "stl.h"
 
-void
-stl_invalidate_shared_vertices(stl_file *stl) {
-  if (stl->error) return;
+void stl_generate_shared_vertices(stl_file *stl, indexed_triangle_set &its)
+{
+	// 3 indices to vertex per face
+	its.indices.assign(stl->stats.number_of_facets, stl_triangle_vertex_indices(-1, -1, -1));
+	// Shared vertices (3D coordinates)
+	its.vertices.clear();
+	its.vertices.reserve(stl->stats.number_of_facets / 2);
 
-  if (stl->v_indices != NULL) {
-    free(stl->v_indices);
-    stl->v_indices = NULL;
-  }
-  if (stl->v_shared != NULL) {
-    free(stl->v_shared);
-    stl->v_shared = NULL;
-  }
+	// A degenerate mesh may contain loops: Traversing a fan will end up in an endless loop
+	// while never reaching the starting face. To avoid these endless loops, traversed faces at each fan traversal
+	// are marked with a unique fan_traversal_stamp.
+	unsigned int			  fan_traversal_stamp = 0;
+	std::vector<unsigned int> fan_traversal_facet_visited(stl->stats.number_of_facets, 0);
+
+	for (uint32_t facet_idx = 0; facet_idx < stl->stats.number_of_facets; ++ facet_idx) {
+		for (int j = 0; j < 3; ++ j) {
+			if (its.indices[facet_idx][j] != -1)
+				// Shared vertex was already assigned.
+				continue;
+			// Create a new shared vertex.
+			its.vertices.emplace_back(stl->facet_start[facet_idx].vertex[j]);
+			// Traverse the fan around the j-th vertex of the i-th face, assign the newly created shared vertex index to all the neighboring triangles in the triangle fan.
+			int  facet_in_fan_idx 	= facet_idx;
+			bool edge_direction 	= false;
+			bool traversal_reversed = false;
+			int  vnot      			= (j + 2) % 3;
+			// Increase the 
+			++ fan_traversal_stamp;
+			for (;;) {
+				// Next edge on facet_in_fan_idx to be traversed. The edge is indexed by its starting vertex index.
+				int next_edge    = 0;
+				// Vertex index in facet_in_fan_idx, which is being pivoted around, and which is being assigned a new shared vertex.
+				int pivot_vertex = 0;
+				if (vnot > 2) {
+					// The edge of facet_in_fan_idx opposite to vnot is equally oriented, therefore
+					// the neighboring facet is flipped.
+			  		if (! edge_direction) {
+			    		pivot_vertex = (vnot + 2) % 3;
+			    		next_edge    = pivot_vertex;			    		
+			  		} else {
+			    		pivot_vertex = (vnot + 1) % 3;
+			    		next_edge    = vnot % 3;
+			  		}
+			  		edge_direction = ! edge_direction;
+				} else {
+					// The neighboring facet is correctly oriented.
+			  		if (! edge_direction) {
+			    		pivot_vertex = (vnot + 1) % 3;
+			    		next_edge    = vnot;
+			  		} else {
+			    		pivot_vertex = (vnot + 2) % 3;
+			    		next_edge    = pivot_vertex;
+			  		}
+				}
+				its.indices[facet_in_fan_idx][pivot_vertex] = its.vertices.size() - 1;
+				fan_traversal_facet_visited[facet_in_fan_idx] = fan_traversal_stamp;
+
+				// next_edge is an index of the starting vertex of the edge, not an index of the opposite vertex to the edge!
+				int next_facet = stl->neighbors_start[facet_in_fan_idx].neighbor[next_edge];
+				if (next_facet == -1) {
+					// No neighbor going in the current direction.
+					if (traversal_reversed) {
+						// Went to one limit, then turned back and reached the other limit. Quit the fan traversal.
+					    break;
+					} else {
+						// Reached the first limit. Now try to reverse and traverse up to the other limit.
+					    edge_direction        = true;
+					    vnot 	         	  = (j + 1) % 3;
+					    traversal_reversed    = true;
+				    	facet_in_fan_idx      = facet_idx;
+					}
+				} else if (next_facet == facet_idx) {
+					// Traversed a closed fan all around.
+//					assert(! traversal_reversed);
+					break;
+				} else if (next_facet >= (int)stl->stats.number_of_facets) {
+					// The mesh is not valid!
+					// assert(false);
+					break;
+				} else if (fan_traversal_facet_visited[next_facet] == fan_traversal_stamp) {
+					// Traversed a closed fan all around, but did not reach the starting face.
+					// This indicates an invalid geometry (non-manifold).
+					//assert(false);
+					break;
+				} else {
+					// Continue traversal.
+					// next_edge is an index of the starting vertex of the edge, not an index of the opposite vertex to the edge!
+					vnot = stl->neighbors_start[facet_in_fan_idx].which_vertex_not[next_edge];
+					facet_in_fan_idx = next_facet;
+				}
+			}
+		}
+	}
 }
 
-void
-stl_generate_shared_vertices(stl_file *stl) {
-  int i;
-  int j;
-  int first_facet;
-  int direction;
-  int facet_num;
-  int vnot;
-  int next_edge;
-  int pivot_vertex;
-  int next_facet;
-  int reversed;
+bool its_write_off(const indexed_triangle_set &its, const char *file)
+{
+	/* Open the file */
+	FILE *fp = boost::nowide::fopen(file, "w");
+	if (fp == nullptr) {
+		BOOST_LOG_TRIVIAL(error) << "stl_write_ascii: Couldn't open " << file << " for writing";
+		return false;
+	}
 
-  if (stl->error) return;
+	fprintf(fp, "OFF\n");
+	fprintf(fp, "%d %d 0\n", (int)its.vertices.size(), (int)its.indices.size());
+	for (int i = 0; i < its.vertices.size(); ++ i)
+		fprintf(fp, "\t%f %f %f\n", its.vertices[i](0), its.vertices[i](1), its.vertices[i](2));
+	for (uint32_t i = 0; i < its.indices.size(); ++ i)
+		fprintf(fp, "\t3 %d %d %d\n", its.indices[i][0], its.indices[i][1], its.indices[i][2]);
+	fclose(fp);
+	return true;
+}
 
-  /* make sure this function is idempotent and does not leak memory */
-  stl_invalidate_shared_vertices(stl);
+bool its_write_vrml(const indexed_triangle_set &its, const char *file)
+{
+	/* Open the file */
+  	FILE *fp = boost::nowide::fopen(file, "w");
+	if (fp == nullptr) {
+		BOOST_LOG_TRIVIAL(error) << "stl_write_vrml: Couldn't open " << file << " for writing";
+		return false;
+	}
 
-  stl->v_indices = (v_indices_struct*)
-                   calloc(stl->stats.number_of_facets, sizeof(v_indices_struct));
-  if(stl->v_indices == NULL) perror("stl_generate_shared_vertices");
-  stl->v_shared = (stl_vertex*)
-                  calloc((stl->stats.number_of_facets / 2), sizeof(stl_vertex));
-  if(stl->v_shared == NULL) perror("stl_generate_shared_vertices");
-  stl->stats.shared_malloced = stl->stats.number_of_facets / 2;
-  stl->stats.shared_vertices = 0;
+	fprintf(fp, "#VRML V1.0 ascii\n\n");
+	fprintf(fp, "Separator {\n");
+	fprintf(fp, "\tDEF STLShape ShapeHints {\n");
+	fprintf(fp, "\t\tvertexOrdering COUNTERCLOCKWISE\n");
+	fprintf(fp, "\t\tfaceType CONVEX\n");
+	fprintf(fp, "\t\tshapeType SOLID\n");
+	fprintf(fp, "\t\tcreaseAngle 0.0\n");
+	fprintf(fp, "\t}\n");
+	fprintf(fp, "\tDEF STLModel Separator {\n");
+	fprintf(fp, "\t\tDEF STLColor Material {\n");
+	fprintf(fp, "\t\t\temissiveColor 0.700000 0.700000 0.000000\n");
+	fprintf(fp, "\t\t}\n");
+	fprintf(fp, "\t\tDEF STLVertices Coordinate3 {\n");
+	fprintf(fp, "\t\t\tpoint [\n");
 
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    stl->v_indices[i].vertex[0] = -1;
-    stl->v_indices[i].vertex[1] = -1;
-    stl->v_indices[i].vertex[2] = -1;
-  }
+	int i = 0;
+	for (; i + 1 < its.vertices.size(); ++ i)
+		fprintf(fp, "\t\t\t\t%f %f %f,\n", its.vertices[i](0), its.vertices[i](1), its.vertices[i](2));
+	fprintf(fp, "\t\t\t\t%f %f %f]\n", its.vertices[i](0), its.vertices[i](1), its.vertices[i](2));
+	fprintf(fp, "\t\t}\n");
+	fprintf(fp, "\t\tDEF STLTriangles IndexedFaceSet {\n");
+	fprintf(fp, "\t\t\tcoordIndex [\n");
+
+	for (size_t i = 0; i + 1 < its.indices.size(); ++ i)
+		fprintf(fp, "\t\t\t\t%d, %d, %d, -1,\n", its.indices[i][0], its.indices[i][1], its.indices[i][2]);
+	fprintf(fp, "\t\t\t\t%d, %d, %d, -1]\n", its.indices[i][0], its.indices[i][1], its.indices[i][2]);
+	fprintf(fp, "\t\t}\n");
+	fprintf(fp, "\t}\n");
+	fprintf(fp, "}\n");
+	fclose(fp);
+	return true;
+}
+
+bool its_write_obj(const indexed_triangle_set &its, const char *file)
+{
+
+  	FILE *fp = boost::nowide::fopen(file, "w");
+  	if (fp == nullptr) {
+		BOOST_LOG_TRIVIAL(error) << "stl_write_obj: Couldn't open " << file << " for writing";
+    	return false;
+  	}
+
+	for (size_t i = 0; i < its.vertices.size(); ++ i)
+    	fprintf(fp, "v %f %f %f\n", its.vertices[i](0), its.vertices[i](1), its.vertices[i](2));
+  	for (size_t i = 0; i < its.indices.size(); ++ i)
+    	fprintf(fp, "f %d %d %d\n", its.indices[i][0]+1, its.indices[i][1]+1, its.indices[i][2]+1);
+  	fclose(fp);
+  	return true;
+}
 
 
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    first_facet = i;
-    for(j = 0; j < 3; j++) {
-      if(stl->v_indices[i].vertex[j] != -1) {
-        continue;
-      }
-      if(stl->stats.shared_vertices == stl->stats.shared_malloced) {
-        stl->stats.shared_malloced += 1024;
-        stl->v_shared = (stl_vertex*)realloc(stl->v_shared,
-                                             stl->stats.shared_malloced * sizeof(stl_vertex));
-        if(stl->v_shared == NULL) perror("stl_generate_shared_vertices");
-      }
+// Check validity of the mesh, assert on error.
+bool stl_validate(const stl_file *stl, const indexed_triangle_set &its)
+{
+	assert(! stl->facet_start.empty());
+	assert(stl->facet_start.size() == stl->stats.number_of_facets);
+	assert(stl->neighbors_start.size() == stl->stats.number_of_facets);
+	assert(stl->facet_start.size() == stl->neighbors_start.size());
+	assert(! stl->neighbors_start.empty());
+	assert((its.indices.empty()) == (its.vertices.empty()));
+	assert(stl->stats.number_of_facets > 0);
+	assert(its.vertices.empty() || its.indices.size() == stl->stats.number_of_facets);
 
-      stl->v_shared[stl->stats.shared_vertices] =
-        stl->facet_start[i].vertex[j];
-
-      direction = 0;
-      reversed = 0;
-      facet_num = i;
-      vnot = (j + 2) % 3;
-
-      for(;;) {
-        if(vnot > 2) {
-          if(direction == 0) {
-            pivot_vertex = (vnot + 2) % 3;
-            next_edge = pivot_vertex;
-            direction = 1;
-          } else {
-            pivot_vertex = (vnot + 1) % 3;
-            next_edge = vnot % 3;
-            direction = 0;
-          }
-        } else {
-          if(direction == 0) {
-            pivot_vertex = (vnot + 1) % 3;
-            next_edge = vnot;
-          } else {
-            pivot_vertex = (vnot + 2) % 3;
-            next_edge = pivot_vertex;
-          }
+#ifdef _DEBUG
+    // Verify validity of neighborship data.
+    for (int facet_idx = 0; facet_idx < (int)stl->stats.number_of_facets; ++ facet_idx) {
+        const stl_neighbors &nbr 		= stl->neighbors_start[facet_idx];
+        const int 			*vertices 	= its.indices.empty() ? nullptr : its.indices[facet_idx].data();
+        for (int nbr_idx = 0; nbr_idx < 3; ++ nbr_idx) {
+            int nbr_face = stl->neighbors_start[facet_idx].neighbor[nbr_idx];
+            assert(nbr_face < (int)stl->stats.number_of_facets);
+            if (nbr_face != -1) {
+            	int nbr_vnot = nbr.which_vertex_not[nbr_idx];
+				assert(nbr_vnot >= 0 && nbr_vnot < 6);
+				// Neighbor of the neighbor is the original face.
+				assert(stl->neighbors_start[nbr_face].neighbor[(nbr_vnot + 1) % 3] == facet_idx);
+				int vnot_back = stl->neighbors_start[nbr_face].which_vertex_not[(nbr_vnot + 1) % 3];
+				assert(vnot_back >= 0 && vnot_back < 6);
+				assert((nbr_vnot < 3) == (vnot_back < 3));
+				assert(vnot_back % 3 == (nbr_idx + 2) % 3);
+				if (vertices != nullptr) {
+					// Has shared vertices.
+	            	if (nbr_vnot < 3) {
+	            		// Faces facet_idx and nbr_face share two vertices accross the common edge. Faces are correctly oriented.
+						assert((its.indices[nbr_face][(nbr_vnot + 1) % 3] == vertices[(nbr_idx + 1) % 3] && its.indices[nbr_face][(nbr_vnot + 2) % 3] == vertices[nbr_idx]));
+					} else {
+	            		// Faces facet_idx and nbr_face share two vertices accross the common edge. Faces are incorrectly oriented, one of them is flipped.
+						assert((its.indices[nbr_face][(nbr_vnot + 2) % 3] == vertices[(nbr_idx + 1) % 3] && its.indices[nbr_face][(nbr_vnot + 1) % 3] == vertices[nbr_idx]));
+					}
+				}
+            }
         }
-        stl->v_indices[facet_num].vertex[pivot_vertex] =
-          stl->stats.shared_vertices;
-
-        next_facet = stl->neighbors_start[facet_num].neighbor[next_edge];
-        if(next_facet == -1) {
-          if(reversed) {
-            break;
-          } else {
-            direction = 1;
-            vnot = (j + 1) % 3;
-            reversed = 1;
-            facet_num = first_facet;
-          }
-        } else if(next_facet != first_facet) {
-          vnot = stl->neighbors_start[facet_num].
-                 which_vertex_not[next_edge];
-          facet_num = next_facet;
-        } else {
-          break;
-        }
-      }
-      stl->stats.shared_vertices += 1;
     }
-  }
+#endif /* _DEBUG */
+
+	return true;
 }
 
-void
-stl_write_off(stl_file *stl, const char *file) {
-  int i;
-  FILE      *fp;
-  char      *error_msg;
-
-  if (stl->error) return;
-
-  /* Open the file */
-  fp = boost::nowide::fopen(file, "w");
-  if(fp == NULL) {
-    error_msg = (char*)
-                malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
-    sprintf(error_msg, "stl_write_ascii: Couldn't open %s for writing",
-            file);
-    perror(error_msg);
-    free(error_msg);
-    stl->error = 1;
-    return;
-  }
-
-  fprintf(fp, "OFF\n");
-  fprintf(fp, "%d %d 0\n",
-          stl->stats.shared_vertices, stl->stats.number_of_facets);
-
-  for(i = 0; i < stl->stats.shared_vertices; i++) {
-    fprintf(fp, "\t%f %f %f\n",
-            stl->v_shared[i](0), stl->v_shared[i](1), stl->v_shared[i](2));
-  }
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    fprintf(fp, "\t3 %d %d %d\n", stl->v_indices[i].vertex[0],
-            stl->v_indices[i].vertex[1], stl->v_indices[i].vertex[2]);
-  }
-  fclose(fp);
-}
-
-void
-stl_write_vrml(stl_file *stl, const char *file) {
-  int i;
-  FILE      *fp;
-  char      *error_msg;
-
-  if (stl->error) return;
-
-  /* Open the file */
-  fp = boost::nowide::fopen(file, "w");
-  if(fp == NULL) {
-    error_msg = (char*)
-                malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
-    sprintf(error_msg, "stl_write_ascii: Couldn't open %s for writing",
-            file);
-    perror(error_msg);
-    free(error_msg);
-    stl->error = 1;
-    return;
-  }
-
-  fprintf(fp, "#VRML V1.0 ascii\n\n");
-  fprintf(fp, "Separator {\n");
-  fprintf(fp, "\tDEF STLShape ShapeHints {\n");
-  fprintf(fp, "\t\tvertexOrdering COUNTERCLOCKWISE\n");
-  fprintf(fp, "\t\tfaceType CONVEX\n");
-  fprintf(fp, "\t\tshapeType SOLID\n");
-  fprintf(fp, "\t\tcreaseAngle 0.0\n");
-  fprintf(fp, "\t}\n");
-  fprintf(fp, "\tDEF STLModel Separator {\n");
-  fprintf(fp, "\t\tDEF STLColor Material {\n");
-  fprintf(fp, "\t\t\temissiveColor 0.700000 0.700000 0.000000\n");
-  fprintf(fp, "\t\t}\n");
-  fprintf(fp, "\t\tDEF STLVertices Coordinate3 {\n");
-  fprintf(fp, "\t\t\tpoint [\n");
-
-  for(i = 0; i < (stl->stats.shared_vertices - 1); i++) {
-    fprintf(fp, "\t\t\t\t%f %f %f,\n",
-            stl->v_shared[i](0), stl->v_shared[i](1), stl->v_shared[i](2));
-  }
-  fprintf(fp, "\t\t\t\t%f %f %f]\n",
-          stl->v_shared[i](0), stl->v_shared[i](1), stl->v_shared[i](2));
-  fprintf(fp, "\t\t}\n");
-  fprintf(fp, "\t\tDEF STLTriangles IndexedFaceSet {\n");
-  fprintf(fp, "\t\t\tcoordIndex [\n");
-
-  for(i = 0; i < (stl->stats.number_of_facets - 1); i++) {
-    fprintf(fp, "\t\t\t\t%d, %d, %d, -1,\n", stl->v_indices[i].vertex[0],
-            stl->v_indices[i].vertex[1], stl->v_indices[i].vertex[2]);
-  }
-  fprintf(fp, "\t\t\t\t%d, %d, %d, -1]\n", stl->v_indices[i].vertex[0],
-          stl->v_indices[i].vertex[1], stl->v_indices[i].vertex[2]);
-  fprintf(fp, "\t\t}\n");
-  fprintf(fp, "\t}\n");
-  fprintf(fp, "}\n");
-  fclose(fp);
-}
-
-void stl_write_obj (stl_file *stl, const char *file) {
-  int i;
-  FILE* fp;
-
-  if (stl->error) return;
-
-  /* Open the file */
-  fp = boost::nowide::fopen(file, "w");
-  if (fp == NULL) {
-    char* error_msg = (char*)malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
-    sprintf(error_msg, "stl_write_ascii: Couldn't open %s for writing", file);
-    perror(error_msg);
-    free(error_msg);
-    stl->error = 1;
-    return;
-  }
-
-  for (i = 0; i < stl->stats.shared_vertices; i++) {
-    fprintf(fp, "v %f %f %f\n", stl->v_shared[i](0), stl->v_shared[i](1), stl->v_shared[i](2));
-  }
-  for (i = 0; i < stl->stats.number_of_facets; i++) {
-    fprintf(fp, "f %d %d %d\n", stl->v_indices[i].vertex[0]+1, stl->v_indices[i].vertex[1]+1, stl->v_indices[i].vertex[2]+1);
-  }
-
-  fclose(fp);
+// Check validity of the mesh, assert on error.
+bool stl_validate(const stl_file *stl)
+{
+	indexed_triangle_set its;
+	return stl_validate(stl, its);
 }
diff --git a/src/admesh/stl.h b/src/admesh/stl.h
index f867e197b..2ac6c7fd2 100644
--- a/src/admesh/stl.h
+++ b/src/admesh/stl.h
@@ -27,6 +27,7 @@
 #include <stdint.h>
 #include <stddef.h>
 
+#include <vector>
 #include <Eigen/Geometry> 
 
 // Size of the binary STL header, free form.
@@ -40,22 +41,23 @@
 
 typedef Eigen::Matrix<float, 3, 1, Eigen::DontAlign> stl_vertex;
 typedef Eigen::Matrix<float, 3, 1, Eigen::DontAlign> stl_normal;
+typedef Eigen::Matrix<int,   3, 1, Eigen::DontAlign> stl_triangle_vertex_indices;
 static_assert(sizeof(stl_vertex) == 12, "size of stl_vertex incorrect");
 static_assert(sizeof(stl_normal) == 12, "size of stl_normal incorrect");
 
 struct stl_facet {
-  stl_normal normal;
-  stl_vertex vertex[3];
-  char       extra[2];
+	stl_normal normal;
+	stl_vertex vertex[3];
+	char       extra[2];
 
-  stl_facet  rotated(const Eigen::Quaternion<float, Eigen::DontAlign> &rot) {
-    stl_facet out;
-    out.normal    = rot * this->normal;
-    out.vertex[0] = rot * this->vertex[0];
-    out.vertex[1] = rot * this->vertex[1];
-    out.vertex[2] = rot * this->vertex[2];
-    return out;
-  }
+	stl_facet  rotated(const Eigen::Quaternion<float, Eigen::DontAlign> &rot) const {
+		stl_facet out;
+		out.normal    = rot * this->normal;
+		out.vertex[0] = rot * this->vertex[0];
+		out.vertex[1] = rot * this->vertex[1];
+		out.vertex[2] = rot * this->vertex[2];
+		return out;
+	}
 };
 
 #define SIZEOF_STL_FACET       50
@@ -67,104 +69,94 @@ static_assert(sizeof(stl_facet) >= SIZEOF_STL_FACET, "size of stl_facet incorrec
 
 typedef enum {binary, ascii, inmemory} stl_type;
 
-typedef struct {
-  stl_vertex p1;
-  stl_vertex p2;
-  int        facet_number;
-} stl_edge;
+struct stl_neighbors {
+  	stl_neighbors() { reset(); }
+  	void reset() {
+  		neighbor[0] = -1;
+  		neighbor[1] = -1;
+  		neighbor[2] = -1;
+  		which_vertex_not[0] = -1;
+  		which_vertex_not[1] = -1;
+  		which_vertex_not[2] = -1;
+  	}
+  	int num_neighbors_missing() const { return (this->neighbor[0] == -1) + (this->neighbor[1] == -1) + (this->neighbor[2] == -1); }
+  	int num_neighbors() const { return 3 - this->num_neighbors_missing(); }
 
-typedef struct stl_hash_edge {
-  // Key of a hash edge: sorted vertices of the edge.
-  uint32_t       key[6];
-  // Compare two keys.
-  bool operator==(const stl_hash_edge &rhs) { return memcmp(key, rhs.key, sizeof(key)) == 0; }
-  bool operator!=(const stl_hash_edge &rhs) { return ! (*this == rhs); }
-  int  hash(int M) const { return ((key[0] / 11 + key[1] / 7 + key[2] / 3) ^ (key[3] / 11  + key[4] / 7 + key[5] / 3)) % M; }
-  // Index of a facet owning this edge.
-  int            facet_number;
-  // Index of this edge inside the facet with an index of facet_number.
-  // If this edge is stored backwards, which_edge is increased by 3.
-  int            which_edge;
-  struct stl_hash_edge  *next;
-} stl_hash_edge;
+  	// Index of a neighbor facet.
+  	int   neighbor[3];
+  	// Index of an opposite vertex at the neighbor face.
+  	char  which_vertex_not[3];
+};
 
-typedef struct {
-  // Index of a neighbor facet.
-  int   neighbor[3];
-  // Index of an opposite vertex at the neighbor face.
-  char  which_vertex_not[3];
-} stl_neighbors;
+struct stl_stats {
+	stl_stats() { this->reset(); }
+	void reset() { memset(this, 0, sizeof(stl_stats)); this->volume = -1.0; }
+	char          header[81];
+	stl_type      type;
+	uint32_t      number_of_facets;
+	stl_vertex    max;
+	stl_vertex    min;
+	stl_vertex    size;
+	float         bounding_diameter;
+	float         shortest_edge;
+	float         volume;
+	int           connected_edges;
+	int           connected_facets_1_edge;
+	int           connected_facets_2_edge;
+	int           connected_facets_3_edge;
+	int           facets_w_1_bad_edge;
+	int           facets_w_2_bad_edge;
+	int           facets_w_3_bad_edge;
+	int           original_num_facets;
+	int           edges_fixed;
+	int           degenerate_facets;
+	int           facets_removed;
+	int           facets_added;
+	int           facets_reversed;
+	int           backwards_edges;
+	int           normals_fixed;
+	int           number_of_parts;
+};
 
-typedef struct {
-  int   vertex[3];
-} v_indices_struct;
+struct stl_file {
+	stl_file() {}
 
-typedef struct {
-  char          header[81];
-  stl_type      type;
-  uint32_t      number_of_facets;
-  stl_vertex    max;
-  stl_vertex    min;
-  stl_vertex    size;
-  float         bounding_diameter;
-  float         shortest_edge;
-  float         volume;
-  unsigned      number_of_blocks;
-  int           connected_edges;
-  int           connected_facets_1_edge;
-  int           connected_facets_2_edge;
-  int           connected_facets_3_edge;
-  int           facets_w_1_bad_edge;
-  int           facets_w_2_bad_edge;
-  int           facets_w_3_bad_edge;
-  int           original_num_facets;
-  int           edges_fixed;
-  int           degenerate_facets;
-  int           facets_removed;
-  int           facets_added;
-  int           facets_reversed;
-  int           backwards_edges;
-  int           normals_fixed;
-  int           number_of_parts;
-  int           malloced;
-  int           freed;
-  int           facets_malloced;
-  int           collisions;
-  int           shared_vertices;
-  int           shared_malloced;
-} stl_stats;
+	void clear() {
+		this->facet_start.clear();
+		this->neighbors_start.clear();
+		this->stats.reset();
+	}
 
-typedef struct {
-  FILE          *fp;
-  stl_facet     *facet_start;
-  stl_hash_edge **heads;
-  stl_hash_edge *tail;
-  int           M;
-  stl_neighbors *neighbors_start;
-  v_indices_struct *v_indices;
-  stl_vertex    *v_shared;
-  stl_stats     stats;
-  char          error;
-} stl_file;
+	std::vector<stl_facet>     		facet_start;
+	std::vector<stl_neighbors> 		neighbors_start;
+	// Statistics
+	stl_stats     					stats;
+};
 
+struct indexed_triangle_set
+{
+	indexed_triangle_set() {}
 
-extern void stl_open(stl_file *stl, const char *file);
-extern void stl_close(stl_file *stl);
+	void clear() { indices.clear(); vertices.clear(); }
+
+	std::vector<stl_triangle_vertex_indices> 	indices;
+	std::vector<stl_vertex>       				vertices;
+	//FIXME add normals once we get rid of the stl_file from TriangleMesh completely.
+	//std::vector<stl_normal> 					normals
+};
+
+extern bool stl_open(stl_file *stl, const char *file);
 extern void stl_stats_out(stl_file *stl, FILE *file, char *input_file);
-extern void stl_print_neighbors(stl_file *stl, char *file);
-extern void stl_put_little_int(FILE *fp, int value_in);
-extern void stl_put_little_float(FILE *fp, float value_in);
-extern void stl_write_ascii(stl_file *stl, const char *file, const char *label);
-extern void stl_write_binary(stl_file *stl, const char *file, const char *label);
-extern void stl_write_binary_block(stl_file *stl, FILE *fp);
+extern bool stl_print_neighbors(stl_file *stl, char *file);
+extern bool stl_write_ascii(stl_file *stl, const char *file, const char *label);
+extern bool stl_write_binary(stl_file *stl, const char *file, const char *label);
 extern void stl_check_facets_exact(stl_file *stl);
 extern void stl_check_facets_nearby(stl_file *stl, float tolerance);
 extern void stl_remove_unconnected_facets(stl_file *stl);
 extern void stl_write_vertex(stl_file *stl, int facet, int vertex);
 extern void stl_write_facet(stl_file *stl, char *label, int facet);
-extern void stl_write_edge(stl_file *stl, char *label, stl_hash_edge edge);
 extern void stl_write_neighbor(stl_file *stl, int facet);
-extern void stl_write_quad_object(stl_file *stl, char *file);
+extern bool stl_write_quad_object(stl_file *stl, char *file);
 extern void stl_verify_neighbors(stl_file *stl);
 extern void stl_fill_holes(stl_file *stl);
 extern void stl_fix_normal_directions(stl_file *stl);
@@ -186,36 +178,30 @@ extern void stl_get_size(stl_file *stl);
 template<typename T>
 extern void stl_transform(stl_file *stl, T *trafo3x4)
 {
-  if (stl->error)
-    return;
+	for (uint32_t i_face = 0; i_face < stl->stats.number_of_facets; ++ i_face) {
+		stl_facet &face = stl->facet_start[i_face];
+		for (int i_vertex = 0; i_vertex < 3; ++ i_vertex) {
+			stl_vertex &v_dst = face.vertex[i_vertex];
+			stl_vertex  v_src = v_dst;
+			v_dst(0) = T(trafo3x4[0] * v_src(0) + trafo3x4[1] * v_src(1) + trafo3x4[2]  * v_src(2) + trafo3x4[3]);
+			v_dst(1) = T(trafo3x4[4] * v_src(0) + trafo3x4[5] * v_src(1) + trafo3x4[6]  * v_src(2) + trafo3x4[7]);
+			v_dst(2) = T(trafo3x4[8] * v_src(0) + trafo3x4[9] * v_src(1) + trafo3x4[10] * v_src(2) + trafo3x4[11]);
+		}
+		stl_vertex &v_dst = face.normal;
+		stl_vertex  v_src = v_dst;
+		v_dst(0) = T(trafo3x4[0] * v_src(0) + trafo3x4[1] * v_src(1) + trafo3x4[2]  * v_src(2));
+		v_dst(1) = T(trafo3x4[4] * v_src(0) + trafo3x4[5] * v_src(1) + trafo3x4[6]  * v_src(2));
+		v_dst(2) = T(trafo3x4[8] * v_src(0) + trafo3x4[9] * v_src(1) + trafo3x4[10] * v_src(2));
+	}
 
-  for (uint32_t i_face = 0; i_face < stl->stats.number_of_facets; ++ i_face) {
-    stl_facet &face = stl->facet_start[i_face];
-    for (int i_vertex = 0; i_vertex < 3; ++ i_vertex) {
-      stl_vertex &v_dst = face.vertex[i_vertex];
-      stl_vertex  v_src = v_dst;
-      v_dst(0) = T(trafo3x4[0] * v_src(0) + trafo3x4[1] * v_src(1) + trafo3x4[2]  * v_src(2) + trafo3x4[3]);
-      v_dst(1) = T(trafo3x4[4] * v_src(0) + trafo3x4[5] * v_src(1) + trafo3x4[6]  * v_src(2) + trafo3x4[7]);
-      v_dst(2) = T(trafo3x4[8] * v_src(0) + trafo3x4[9] * v_src(1) + trafo3x4[10] * v_src(2) + trafo3x4[11]);
-    }
-    stl_vertex &v_dst = face.normal;
-    stl_vertex  v_src = v_dst;
-    v_dst(0) = T(trafo3x4[0] * v_src(0) + trafo3x4[1] * v_src(1) + trafo3x4[2]  * v_src(2));
-    v_dst(1) = T(trafo3x4[4] * v_src(0) + trafo3x4[5] * v_src(1) + trafo3x4[6]  * v_src(2));
-    v_dst(2) = T(trafo3x4[8] * v_src(0) + trafo3x4[9] * v_src(1) + trafo3x4[10] * v_src(2));
-  }
-
-  stl_get_size(stl);
+	stl_get_size(stl);
 }
 
 template<typename T>
 inline void stl_transform(stl_file *stl, const Eigen::Transform<T, 3, Eigen::Affine, Eigen::DontAlign>& t)
 {
-	if (stl->error)
-		return;
-
 	const Eigen::Matrix<double, 3, 3, Eigen::DontAlign> r = t.matrix().template block<3, 3>(0, 0);
-	for (size_t i = 0; i < stl->stats.number_of_facets; ++i) {
+	for (size_t i = 0; i < stl->stats.number_of_facets; ++ i) {
 		stl_facet &f = stl->facet_start[i];
 		for (size_t j = 0; j < 3; ++j)
 			f.vertex[j] = (t * f.vertex[j].template cast<T>()).template cast<float>().eval();
@@ -228,10 +214,7 @@ inline void stl_transform(stl_file *stl, const Eigen::Transform<T, 3, Eigen::Aff
 template<typename T>
 inline void stl_transform(stl_file *stl, const Eigen::Matrix<T, 3, 3, Eigen::DontAlign>& m)
 {
-	if (stl->error)
-		return;
-
-	for (size_t i = 0; i < stl->stats.number_of_facets; ++i) {
+	for (size_t i = 0; i < stl->stats.number_of_facets; ++ i) {
 		stl_facet &f = stl->facet_start[i];
 		for (size_t j = 0; j < 3; ++j)
 			f.vertex[j] = (m * f.vertex[j].template cast<T>()).template cast<float>().eval();
@@ -241,13 +224,43 @@ inline void stl_transform(stl_file *stl, const Eigen::Matrix<T, 3, 3, Eigen::Don
 	stl_get_size(stl);
 }
 
-extern void stl_open_merge(stl_file *stl, char *file);
-extern void stl_invalidate_shared_vertices(stl_file *stl);
-extern void stl_generate_shared_vertices(stl_file *stl);
-extern void stl_write_obj(stl_file *stl, const char *file);
-extern void stl_write_off(stl_file *stl, const char *file);
-extern void stl_write_dxf(stl_file *stl, const char *file, char *label);
-extern void stl_write_vrml(stl_file *stl, const char *file);
+
+template<typename T>
+extern void its_transform(indexed_triangle_set &its, T *trafo3x4)
+{
+	for (stl_vertex &v_dst : its.vertices) {
+		stl_vertex  v_src = v_dst;
+		v_dst(0) = T(trafo3x4[0] * v_src(0) + trafo3x4[1] * v_src(1) + trafo3x4[2]  * v_src(2) + trafo3x4[3]);
+		v_dst(1) = T(trafo3x4[4] * v_src(0) + trafo3x4[5] * v_src(1) + trafo3x4[6]  * v_src(2) + trafo3x4[7]);
+		v_dst(2) = T(trafo3x4[8] * v_src(0) + trafo3x4[9] * v_src(1) + trafo3x4[10] * v_src(2) + trafo3x4[11]);
+	}
+}
+
+template<typename T>
+inline void its_transform(indexed_triangle_set &its, const Eigen::Transform<T, 3, Eigen::Affine, Eigen::DontAlign>& t)
+{
+	const Eigen::Matrix<double, 3, 3, Eigen::DontAlign> r = t.matrix().template block<3, 3>(0, 0);
+	for (stl_vertex &v : its.vertices)
+		v = (t * v.template cast<T>()).template cast<float>().eval();
+}
+
+template<typename T>
+inline void its_transform(indexed_triangle_set &its, const Eigen::Matrix<T, 3, 3, Eigen::DontAlign>& m)
+{
+	for (stl_vertex &v : its.vertices)
+		v = (m * v.template cast<T>()).template cast<float>().eval();
+}
+
+extern void its_rotate_x(indexed_triangle_set &its, float angle);
+extern void its_rotate_y(indexed_triangle_set &its, float angle);
+extern void its_rotate_z(indexed_triangle_set &its, float angle);
+
+extern void stl_generate_shared_vertices(stl_file *stl, indexed_triangle_set &its);
+extern bool its_write_obj(const indexed_triangle_set &its, const char *file);
+extern bool its_write_off(const indexed_triangle_set &its, const char *file);
+extern bool its_write_vrml(const indexed_triangle_set &its, const char *file);
+
+extern bool stl_write_dxf(stl_file *stl, const char *file, char *label);
 inline void stl_calculate_normal(stl_normal &normal, stl_facet *facet) {
   normal = (facet->vertex[1] - facet->vertex[0]).cross(facet->vertex[2] - facet->vertex[0]);
 }
@@ -258,24 +271,18 @@ inline void stl_normalize_vector(stl_normal &normal) {
   else
     normal *= float(1.0 / length);
 }
-inline bool stl_vertex_lower(const stl_vertex &a, const stl_vertex &b) {
-  return (a(0) != b(0)) ? (a(0) < b(0)) :
-        ((a(1) != b(1)) ? (a(1) < b(1)) : (a(2) < b(2)));
-}
 extern void stl_calculate_volume(stl_file *stl);
 
-extern void stl_repair(stl_file *stl, int fixall_flag, int exact_flag, int tolerance_flag, float tolerance, int increment_flag, float increment, int nearby_flag, int iterations, int remove_unconnected_flag, int fill_holes_flag, int normal_directions_flag, int normal_values_flag, int reverse_all_flag, int verbose_flag);
+extern void stl_repair(stl_file *stl, bool fixall_flag, bool exact_flag, bool tolerance_flag, float tolerance, bool increment_flag, float increment, bool nearby_flag, int iterations, bool remove_unconnected_flag, bool fill_holes_flag, bool normal_directions_flag, bool normal_values_flag, bool reverse_all_flag, bool verbose_flag);
 
-extern void stl_initialize(stl_file *stl);
-extern void stl_count_facets(stl_file *stl, const char *file);
 extern void stl_allocate(stl_file *stl);
 extern void stl_read(stl_file *stl, int first_facet, bool first);
 extern void stl_facet_stats(stl_file *stl, stl_facet facet, bool &first);
 extern void stl_reallocate(stl_file *stl);
-extern void stl_add_facet(stl_file *stl, stl_facet *new_facet);
+extern void stl_add_facet(stl_file *stl, const stl_facet *new_facet);
 
-extern void stl_clear_error(stl_file *stl);
-extern int stl_get_error(stl_file *stl);
-extern void stl_exit_on_error(stl_file *stl);
+// Validate the mesh, assert on error.
+extern bool stl_validate(const stl_file *stl);
+extern bool stl_validate(const stl_file *stl, const indexed_triangle_set &its);
 
 #endif
diff --git a/src/admesh/stl_io.cpp b/src/admesh/stl_io.cpp
index 85f66785b..464c98907 100644
--- a/src/admesh/stl_io.cpp
+++ b/src/admesh/stl_io.cpp
@@ -22,159 +22,86 @@
 
 #include <stdlib.h>
 #include <string.h>
+
+#include <boost/log/trivial.hpp>
+#include <boost/nowide/cstdio.hpp>
+#include <boost/predef/other/endian.h>
+
 #include "stl.h"
 
-#include <boost/nowide/cstdio.hpp>
-#include <boost/detail/endian.hpp>
-
-#if !defined(SEEK_SET)
-#define SEEK_SET 0
-#define SEEK_CUR 1
-#define SEEK_END 2
-#endif
-
-void
-stl_stats_out(stl_file *stl, FILE *file, char *input_file) {
-  if (stl->error) return;
-
-  /* this is here for Slic3r, without our config.h
-     it won't use this part of the code anyway */
+void stl_stats_out(stl_file *stl, FILE *file, char *input_file)
+{
+  	// This is here for Slic3r, without our config.h it won't use this part of the code anyway.
 #ifndef VERSION
 #define VERSION "unknown"
 #endif
-  fprintf(file, "\n\
-================= Results produced by ADMesh version " VERSION " ================\n");
-  fprintf(file, "\
-Input file         : %s\n", input_file);
-  if(stl->stats.type == binary) {
-    fprintf(file, "\
-File type          : Binary STL file\n");
-  } else {
-    fprintf(file, "\
-File type          : ASCII STL file\n");
-  }
-  fprintf(file, "\
-Header             : %s\n", stl->stats.header);
-  fprintf(file, "============== Size ==============\n");
-  fprintf(file, "Min X = % f, Max X = % f\n",
-          stl->stats.min(0), stl->stats.max(0));
-  fprintf(file, "Min Y = % f, Max Y = % f\n",
-          stl->stats.min(1), stl->stats.max(1));
-  fprintf(file, "Min Z = % f, Max Z = % f\n",
-          stl->stats.min(2), stl->stats.max(2));
-
-  fprintf(file, "\
-========= Facet Status ========== Original ============ Final ====\n");
-  fprintf(file, "\
-Number of facets                 : %5d               %5d\n",
-          stl->stats.original_num_facets, stl->stats.number_of_facets);
-  fprintf(file, "\
-Facets with 1 disconnected edge  : %5d               %5d\n",
-          stl->stats.facets_w_1_bad_edge, stl->stats.connected_facets_2_edge -
-          stl->stats.connected_facets_3_edge);
-  fprintf(file, "\
-Facets with 2 disconnected edges : %5d               %5d\n",
-          stl->stats.facets_w_2_bad_edge, stl->stats.connected_facets_1_edge -
-          stl->stats.connected_facets_2_edge);
-  fprintf(file, "\
-Facets with 3 disconnected edges : %5d               %5d\n",
-          stl->stats.facets_w_3_bad_edge, stl->stats.number_of_facets -
-          stl->stats.connected_facets_1_edge);
-  fprintf(file, "\
-Total disconnected facets        : %5d               %5d\n",
-          stl->stats.facets_w_1_bad_edge + stl->stats.facets_w_2_bad_edge +
-          stl->stats.facets_w_3_bad_edge, stl->stats.number_of_facets -
-          stl->stats.connected_facets_3_edge);
-
-  fprintf(file,
-          "=== Processing Statistics ===     ===== Other Statistics =====\n");
-  fprintf(file, "\
-Number of parts       : %5d        Volume   : % f\n",
-          stl->stats.number_of_parts, stl->stats.volume);
-  fprintf(file, "\
-Degenerate facets     : %5d\n", stl->stats.degenerate_facets);
-  fprintf(file, "\
-Edges fixed           : %5d\n", stl->stats.edges_fixed);
-  fprintf(file, "\
-Facets removed        : %5d\n", stl->stats.facets_removed);
-  fprintf(file, "\
-Facets added          : %5d\n", stl->stats.facets_added);
-  fprintf(file, "\
-Facets reversed       : %5d\n", stl->stats.facets_reversed);
-  fprintf(file, "\
-Backwards edges       : %5d\n", stl->stats.backwards_edges);
-  fprintf(file, "\
-Normals fixed         : %5d\n", stl->stats.normals_fixed);
+  	fprintf(file, "\n================= Results produced by ADMesh version " VERSION " ================\n");
+  	fprintf(file, "Input file         : %s\n", input_file);
+  	if (stl->stats.type == binary)
+    	fprintf(file, "File type          : Binary STL file\n");
+  	else
+    	fprintf(file, "File type          : ASCII STL file\n");
+  	fprintf(file, "Header             : %s\n", stl->stats.header);
+  	fprintf(file, "============== Size ==============\n");
+  	fprintf(file, "Min X = % f, Max X = % f\n", stl->stats.min(0), stl->stats.max(0));
+  	fprintf(file, "Min Y = % f, Max Y = % f\n", stl->stats.min(1), stl->stats.max(1));
+  	fprintf(file, "Min Z = % f, Max Z = % f\n", stl->stats.min(2), stl->stats.max(2));
+  	fprintf(file, "========= Facet Status ========== Original ============ Final ====\n");
+  	fprintf(file, "Number of facets                 : %5d               %5d\n", stl->stats.original_num_facets, stl->stats.number_of_facets);
+  	fprintf(file, "Facets with 1 disconnected edge  : %5d               %5d\n", 
+  		stl->stats.facets_w_1_bad_edge, stl->stats.connected_facets_2_edge - stl->stats.connected_facets_3_edge);
+  	fprintf(file, "Facets with 2 disconnected edges : %5d               %5d\n",
+    	stl->stats.facets_w_2_bad_edge, stl->stats.connected_facets_1_edge - stl->stats.connected_facets_2_edge);
+  	fprintf(file, "Facets with 3 disconnected edges : %5d               %5d\n",
+        stl->stats.facets_w_3_bad_edge, stl->stats.number_of_facets - stl->stats.connected_facets_1_edge);
+  	fprintf(file, "Total disconnected facets        : %5d               %5d\n",
+		stl->stats.facets_w_1_bad_edge + stl->stats.facets_w_2_bad_edge + stl->stats.facets_w_3_bad_edge, stl->stats.number_of_facets - stl->stats.connected_facets_3_edge);
+  	fprintf(file, "=== Processing Statistics ===     ===== Other Statistics =====\n");
+  	fprintf(file, "Number of parts       : %5d        Volume   : %f\n", stl->stats.number_of_parts, stl->stats.volume);
+  	fprintf(file, "Degenerate facets     : %5d\n", stl->stats.degenerate_facets);
+  	fprintf(file, "Edges fixed           : %5d\n", stl->stats.edges_fixed);
+  	fprintf(file, "Facets removed        : %5d\n", stl->stats.facets_removed);
+  	fprintf(file, "Facets added          : %5d\n", stl->stats.facets_added);
+  	fprintf(file, "Facets reversed       : %5d\n", stl->stats.facets_reversed);
+  	fprintf(file, "Backwards edges       : %5d\n", stl->stats.backwards_edges);
+  	fprintf(file, "Normals fixed         : %5d\n", stl->stats.normals_fixed);
 }
 
-void
-stl_write_ascii(stl_file *stl, const char *file, const char *label) {
-  int       i;
-  char      *error_msg;
+bool stl_write_ascii(stl_file *stl, const char *file, const char *label)
+{
+	FILE *fp = boost::nowide::fopen(file, "w");
+  	if (fp == nullptr) {
+		BOOST_LOG_TRIVIAL(error) << "stl_write_ascii: Couldn't open " << file << " for writing";
+    	return false;
+  	}
 
-  if (stl->error) return;
+	fprintf(fp, "solid  %s\n", label);
 
-  /* Open the file */
-  FILE *fp = boost::nowide::fopen(file, "w");
-  if(fp == NULL) {
-    error_msg = (char*)
-                malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
-    sprintf(error_msg, "stl_write_ascii: Couldn't open %s for writing",
-            file);
-    perror(error_msg);
-    free(error_msg);
-    stl->error = 1;
-    return;
-  }
+	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+		fprintf(fp, "  facet normal % .8E % .8E % .8E\n", stl->facet_start[i].normal(0), stl->facet_start[i].normal(1), stl->facet_start[i].normal(2));
+		fprintf(fp, "    outer loop\n");
+		fprintf(fp, "      vertex % .8E % .8E % .8E\n", stl->facet_start[i].vertex[0](0), stl->facet_start[i].vertex[0](1), stl->facet_start[i].vertex[0](2));
+		fprintf(fp, "      vertex % .8E % .8E % .8E\n", stl->facet_start[i].vertex[1](0), stl->facet_start[i].vertex[1](1), stl->facet_start[i].vertex[1](2));
+		fprintf(fp, "      vertex % .8E % .8E % .8E\n", stl->facet_start[i].vertex[2](0), stl->facet_start[i].vertex[2](1), stl->facet_start[i].vertex[2](2));
+		fprintf(fp, "    endloop\n");
+		fprintf(fp, "  endfacet\n");
+	}
 
-  fprintf(fp, "solid  %s\n", label);
-
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    fprintf(fp, "  facet normal % .8E % .8E % .8E\n",
-            stl->facet_start[i].normal(0), stl->facet_start[i].normal(1),
-            stl->facet_start[i].normal(2));
-    fprintf(fp, "    outer loop\n");
-    fprintf(fp, "      vertex % .8E % .8E % .8E\n",
-            stl->facet_start[i].vertex[0](0), stl->facet_start[i].vertex[0](1),
-            stl->facet_start[i].vertex[0](2));
-    fprintf(fp, "      vertex % .8E % .8E % .8E\n",
-            stl->facet_start[i].vertex[1](0), stl->facet_start[i].vertex[1](1),
-            stl->facet_start[i].vertex[1](2));
-    fprintf(fp, "      vertex % .8E % .8E % .8E\n",
-            stl->facet_start[i].vertex[2](0), stl->facet_start[i].vertex[2](1),
-            stl->facet_start[i].vertex[2](2));
-    fprintf(fp, "    endloop\n");
-    fprintf(fp, "  endfacet\n");
-  }
-
-  fprintf(fp, "endsolid  %s\n", label);
-
-  fclose(fp);
+  	fprintf(fp, "endsolid  %s\n", label);
+  	fclose(fp);
+  	return true;
 }
 
-void
-stl_print_neighbors(stl_file *stl, char *file) {
-  int i;
-  FILE *fp;
-  char *error_msg;
+bool stl_print_neighbors(stl_file *stl, char *file)
+{
+	FILE *fp = boost::nowide::fopen(file, "w");
+	if (fp == nullptr) {
+		BOOST_LOG_TRIVIAL(error) << "stl_print_neighbors: Couldn't open " << file << " for writing";
+    	return false;
+  	}
 
-  if (stl->error) return;
-
-  /* Open the file */
-  fp = boost::nowide::fopen(file, "w");
-  if(fp == NULL) {
-    error_msg = (char*)
-                malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
-    sprintf(error_msg, "stl_print_neighbors: Couldn't open %s for writing",
-            file);
-    perror(error_msg);
-    free(error_msg);
-    stl->error = 1;
-    return;
-  }
-
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    fprintf(fp, "%d, %d,%d, %d,%d, %d,%d\n",
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+    	fprintf(fp, "%d, %d,%d, %d,%d, %d,%d\n",
             i,
             stl->neighbors_start[i].neighbor[0],
             (int)stl->neighbors_start[i].which_vertex_not[0],
@@ -182,234 +109,142 @@ stl_print_neighbors(stl_file *stl, char *file) {
             (int)stl->neighbors_start[i].which_vertex_not[1],
             stl->neighbors_start[i].neighbor[2],
             (int)stl->neighbors_start[i].which_vertex_not[2]);
-  }
-  fclose(fp);
+  	}
+  	fclose(fp);
+  	return true;
 }
 
-#ifndef BOOST_LITTLE_ENDIAN
+#if BOOST_ENDIAN_BIG_BYTE
 // Swap a buffer of 32bit data from little endian to big endian and vice versa.
 void stl_internal_reverse_quads(char *buf, size_t cnt)
 {
-  for (size_t i = 0; i < cnt; i += 4) {
-    std::swap(buf[i], buf[i+3]);
-    std::swap(buf[i+1], buf[i+2]);
-  }
+	for (size_t i = 0; i < cnt; i += 4) {
+		std::swap(buf[i], buf[i+3]);
+		std::swap(buf[i+1], buf[i+2]);
+	}
 }
 #endif
 
-void
-stl_write_binary(stl_file *stl, const char *file, const char *label) {
-  FILE      *fp;
-  int       i;
-  char      *error_msg;
+bool stl_write_binary(stl_file *stl, const char *file, const char *label)
+{
+	FILE *fp = boost::nowide::fopen(file, "wb");
+	if (fp == nullptr) {
+		BOOST_LOG_TRIVIAL(error) << "stl_write_binary: Couldn't open " << file << " for writing";
+    	return false;
+  	}
 
-  if (stl->error) return;
+	fprintf(fp, "%s", label);
+	for (size_t i = strlen(label); i < LABEL_SIZE; ++ i)
+		putc(0, fp);
 
-  /* Open the file */
-  fp = boost::nowide::fopen(file, "wb");
-  if(fp == NULL) {
-    error_msg = (char*)
-                malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
-    sprintf(error_msg, "stl_write_binary: Couldn't open %s for writing",
-            file);
-    perror(error_msg);
-    free(error_msg);
-    stl->error = 1;
-    return;
-  }
-
-  fprintf(fp, "%s", label);
-  for(i = strlen(label); i < LABEL_SIZE; i++) putc(0, fp);
-
-  fseek(fp, LABEL_SIZE, SEEK_SET);
-#ifdef BOOST_LITTLE_ENDIAN
-  fwrite(&stl->stats.number_of_facets, 4, 1, fp);
-  for (i = 0; i < stl->stats.number_of_facets; ++ i)
-    fwrite(stl->facet_start + i, SIZEOF_STL_FACET, 1, fp);
-#else /* BOOST_LITTLE_ENDIAN */
-  char buffer[50];
-  // Convert the number of facets to little endian.
-  memcpy(buffer, &stl->stats.number_of_facets, 4);
-  stl_internal_reverse_quads(buffer, 4);
-  fwrite(buffer, 4, 1, fp);
-  for (i = 0; i < stl->stats.number_of_facets; ++ i) {
-    memcpy(buffer, stl->facet_start + i, 50);
-    // Convert to little endian.
-    stl_internal_reverse_quads(buffer, 48);
-    fwrite(buffer, SIZEOF_STL_FACET, 1, fp);
-  }
-#endif /* BOOST_LITTLE_ENDIAN */
-  fclose(fp);
+#if !defined(SEEK_SET)
+	#define SEEK_SET 0
+#endif
+	fseek(fp, LABEL_SIZE, SEEK_SET);
+#if BOOST_ENDIAN_LITTLE_BYTE
+	fwrite(&stl->stats.number_of_facets, 4, 1, fp);
+	for (const stl_facet &facet : stl->facet_start)
+	  	fwrite(&facet, SIZEOF_STL_FACET, 1, fp);
+#else /* BOOST_ENDIAN_LITTLE_BYTE */
+	char buffer[50];
+	// Convert the number of facets to little endian.
+	memcpy(buffer, &stl->stats.number_of_facets, 4);
+	stl_internal_reverse_quads(buffer, 4);
+	fwrite(buffer, 4, 1, fp);
+	for (i = 0; i < stl->stats.number_of_facets; ++ i) {
+		memcpy(buffer, stl->facet_start + i, 50);
+		// Convert to little endian.
+		stl_internal_reverse_quads(buffer, 48);
+		fwrite(buffer, SIZEOF_STL_FACET, 1, fp);
+	}
+#endif /* BOOST_ENDIAN_LITTLE_BYTE */
+	fclose(fp);
+	return true;
 }
 
-void
-stl_write_vertex(stl_file *stl, int facet, int vertex) {
-  if (stl->error) return;
-  printf("  vertex %d/%d % .8E % .8E % .8E\n", vertex, facet,
+void stl_write_vertex(stl_file *stl, int facet, int vertex)
+{
+  	printf("  vertex %d/%d % .8E % .8E % .8E\n", vertex, facet,
          stl->facet_start[facet].vertex[vertex](0),
          stl->facet_start[facet].vertex[vertex](1),
          stl->facet_start[facet].vertex[vertex](2));
 }
 
-void
-stl_write_facet(stl_file *stl, char *label, int facet) {
-  if (stl->error) return;
-  printf("facet (%d)/ %s\n", facet, label);
-  stl_write_vertex(stl, facet, 0);
-  stl_write_vertex(stl, facet, 1);
-  stl_write_vertex(stl, facet, 2);
+void stl_write_facet(stl_file *stl, char *label, int facet)
+{
+	printf("facet (%d)/ %s\n", facet, label);
+	stl_write_vertex(stl, facet, 0);
+	stl_write_vertex(stl, facet, 1);
+	stl_write_vertex(stl, facet, 2);
 }
 
-void
-stl_write_edge(stl_file *stl, char *label, stl_hash_edge edge) {
-  if (stl->error) return;
-  printf("edge (%d)/(%d) %s\n", edge.facet_number, edge.which_edge, label);
-  if(edge.which_edge < 3) {
-    stl_write_vertex(stl, edge.facet_number, edge.which_edge % 3);
-    stl_write_vertex(stl, edge.facet_number, (edge.which_edge + 1) % 3);
-  } else {
-    stl_write_vertex(stl, edge.facet_number, (edge.which_edge + 1) % 3);
-    stl_write_vertex(stl, edge.facet_number, edge.which_edge % 3);
-  }
+void stl_write_neighbor(stl_file *stl, int facet)
+{
+	printf("Neighbors %d: %d, %d, %d ;  %d, %d, %d\n", facet,
+		stl->neighbors_start[facet].neighbor[0],
+		stl->neighbors_start[facet].neighbor[1],
+		stl->neighbors_start[facet].neighbor[2],
+		stl->neighbors_start[facet].which_vertex_not[0],
+		stl->neighbors_start[facet].which_vertex_not[1],
+		stl->neighbors_start[facet].which_vertex_not[2]);
 }
 
-void
-stl_write_neighbor(stl_file *stl, int facet) {
-  if (stl->error) return;
-  printf("Neighbors %d: %d, %d, %d ;  %d, %d, %d\n", facet,
-         stl->neighbors_start[facet].neighbor[0],
-         stl->neighbors_start[facet].neighbor[1],
-         stl->neighbors_start[facet].neighbor[2],
-         stl->neighbors_start[facet].which_vertex_not[0],
-         stl->neighbors_start[facet].which_vertex_not[1],
-         stl->neighbors_start[facet].which_vertex_not[2]);
-}
+bool stl_write_quad_object(stl_file *stl, char *file)
+{
+	stl_vertex connect_color = stl_vertex::Zero();
+	stl_vertex uncon_1_color = stl_vertex::Zero();
+	stl_vertex uncon_2_color = stl_vertex::Zero();
+	stl_vertex uncon_3_color = stl_vertex::Zero();
+	stl_vertex color;
 
-void
-stl_write_quad_object(stl_file *stl, char *file) {
-  FILE      *fp;
-  int       i;
-  int       j;
-  char      *error_msg;
-  stl_vertex connect_color = stl_vertex::Zero();
-  stl_vertex uncon_1_color = stl_vertex::Zero();
-  stl_vertex uncon_2_color = stl_vertex::Zero();
-  stl_vertex uncon_3_color = stl_vertex::Zero();
-  stl_vertex color;
+	FILE *fp = boost::nowide::fopen(file, "w");
+	if (fp == nullptr) {
+		BOOST_LOG_TRIVIAL(error) << "stl_write_quad_object: Couldn't open " << file << " for writing";
+		return false;
+	}
 
-  if (stl->error) return;
-
-  /* Open the file */
-  fp = boost::nowide::fopen(file, "w");
-  if(fp == NULL) {
-    error_msg = (char*)
-                malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
-    sprintf(error_msg, "stl_write_quad_object: Couldn't open %s for writing",
-            file);
-    perror(error_msg);
-    free(error_msg);
-    stl->error = 1;
-    return;
-  }
-
-  fprintf(fp, "CQUAD\n");
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    j = ((stl->neighbors_start[i].neighbor[0] == -1) +
-         (stl->neighbors_start[i].neighbor[1] == -1) +
-         (stl->neighbors_start[i].neighbor[2] == -1));
-    if(j == 0) {
-      color = connect_color;
-    } else if(j == 1) {
-      color = uncon_1_color;
-    } else if(j == 2) {
-      color = uncon_2_color;
-    } else {
-      color = uncon_3_color;
-    }
-    fprintf(fp, "%f %f %f    %1.1f %1.1f %1.1f 1\n",
-            stl->facet_start[i].vertex[0](0),
-            stl->facet_start[i].vertex[0](1),
-            stl->facet_start[i].vertex[0](2), color(0), color(1), color(2));
-    fprintf(fp, "%f %f %f    %1.1f %1.1f %1.1f 1\n",
-            stl->facet_start[i].vertex[1](0),
-            stl->facet_start[i].vertex[1](1),
-            stl->facet_start[i].vertex[1](2), color(0), color(1), color(2));
-    fprintf(fp, "%f %f %f    %1.1f %1.1f %1.1f 1\n",
-            stl->facet_start[i].vertex[2](0),
-            stl->facet_start[i].vertex[2](1),
-            stl->facet_start[i].vertex[2](2), color(0), color(1), color(2));
-    fprintf(fp, "%f %f %f    %1.1f %1.1f %1.1f 1\n",
-            stl->facet_start[i].vertex[2](0),
-            stl->facet_start[i].vertex[2](1),
-            stl->facet_start[i].vertex[2](2), color(0), color(1), color(2));
+  	fprintf(fp, "CQUAD\n");
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+  		switch (stl->neighbors_start[i].num_neighbors_missing()) {
+  		case 0: color = connect_color; break;
+    	case 1: color = uncon_1_color; break;
+    	case 2: color = uncon_2_color; break;
+    	default: color = uncon_3_color;
+	    }
+	    fprintf(fp, "%f %f %f    %1.1f %1.1f %1.1f 1\n", stl->facet_start[i].vertex[0](0), stl->facet_start[i].vertex[0](1), stl->facet_start[i].vertex[0](2), color(0), color(1), color(2));
+    	fprintf(fp, "%f %f %f    %1.1f %1.1f %1.1f 1\n", stl->facet_start[i].vertex[1](0), stl->facet_start[i].vertex[1](1), stl->facet_start[i].vertex[1](2), color(0), color(1), color(2));
+    	fprintf(fp, "%f %f %f    %1.1f %1.1f %1.1f 1\n", stl->facet_start[i].vertex[2](0), stl->facet_start[i].vertex[2](1), stl->facet_start[i].vertex[2](2), color(0), color(1), color(2));
+    	fprintf(fp, "%f %f %f    %1.1f %1.1f %1.1f 1\n", stl->facet_start[i].vertex[2](0), stl->facet_start[i].vertex[2](1), stl->facet_start[i].vertex[2](2), color(0), color(1), color(2));
   }
   fclose(fp);
+  return true;
 }
 
-void
-stl_write_dxf(stl_file *stl, const char *file, char *label) {
-  int       i;
-  FILE      *fp;
-  char      *error_msg;
+bool stl_write_dxf(stl_file *stl, const char *file, char *label) 
+{
+	FILE *fp = boost::nowide::fopen(file, "w");
+	if (fp == nullptr) {
+		BOOST_LOG_TRIVIAL(error) << "stl_write_quad_object: Couldn't open " << file << " for writing";
+    	return false;
+  	}
 
-  if (stl->error) return;
+	fprintf(fp, "999\n%s\n", label);
+	fprintf(fp, "0\nSECTION\n2\nHEADER\n0\nENDSEC\n");
+	fprintf(fp, "0\nSECTION\n2\nTABLES\n0\nTABLE\n2\nLAYER\n70\n1\n\
+	0\nLAYER\n2\n0\n70\n0\n62\n7\n6\nCONTINUOUS\n0\nENDTAB\n0\nENDSEC\n");
+	fprintf(fp, "0\nSECTION\n2\nBLOCKS\n0\nENDSEC\n");
 
-  /* Open the file */
-  fp = boost::nowide::fopen(file, "w");
-  if(fp == NULL) {
-    error_msg = (char*)
-                malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
-    sprintf(error_msg, "stl_write_ascii: Couldn't open %s for writing",
-            file);
-    perror(error_msg);
-    free(error_msg);
-    stl->error = 1;
-    return;
-  }
+	fprintf(fp, "0\nSECTION\n2\nENTITIES\n");
 
-  fprintf(fp, "999\n%s\n", label);
-  fprintf(fp, "0\nSECTION\n2\nHEADER\n0\nENDSEC\n");
-  fprintf(fp, "0\nSECTION\n2\nTABLES\n0\nTABLE\n2\nLAYER\n70\n1\n\
-0\nLAYER\n2\n0\n70\n0\n62\n7\n6\nCONTINUOUS\n0\nENDTAB\n0\nENDSEC\n");
-  fprintf(fp, "0\nSECTION\n2\nBLOCKS\n0\nENDSEC\n");
+	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+		fprintf(fp, "0\n3DFACE\n8\n0\n");
+		fprintf(fp, "10\n%f\n20\n%f\n30\n%f\n", stl->facet_start[i].vertex[0](0), stl->facet_start[i].vertex[0](1), stl->facet_start[i].vertex[0](2));
+		fprintf(fp, "11\n%f\n21\n%f\n31\n%f\n", stl->facet_start[i].vertex[1](0), stl->facet_start[i].vertex[1](1), stl->facet_start[i].vertex[1](2));
+		fprintf(fp, "12\n%f\n22\n%f\n32\n%f\n", stl->facet_start[i].vertex[2](0), stl->facet_start[i].vertex[2](1), stl->facet_start[i].vertex[2](2));
+		fprintf(fp, "13\n%f\n23\n%f\n33\n%f\n", stl->facet_start[i].vertex[2](0), stl->facet_start[i].vertex[2](1), stl->facet_start[i].vertex[2](2));
+	}
 
-  fprintf(fp, "0\nSECTION\n2\nENTITIES\n");
-
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    fprintf(fp, "0\n3DFACE\n8\n0\n");
-    fprintf(fp, "10\n%f\n20\n%f\n30\n%f\n",
-            stl->facet_start[i].vertex[0](0), stl->facet_start[i].vertex[0](1),
-            stl->facet_start[i].vertex[0](2));
-    fprintf(fp, "11\n%f\n21\n%f\n31\n%f\n",
-            stl->facet_start[i].vertex[1](0), stl->facet_start[i].vertex[1](1),
-            stl->facet_start[i].vertex[1](2));
-    fprintf(fp, "12\n%f\n22\n%f\n32\n%f\n",
-            stl->facet_start[i].vertex[2](0), stl->facet_start[i].vertex[2](1),
-            stl->facet_start[i].vertex[2](2));
-    fprintf(fp, "13\n%f\n23\n%f\n33\n%f\n",
-            stl->facet_start[i].vertex[2](0), stl->facet_start[i].vertex[2](1),
-            stl->facet_start[i].vertex[2](2));
-  }
-
-  fprintf(fp, "0\nENDSEC\n0\nEOF\n");
-
-  fclose(fp);
-}
-
-void
-stl_clear_error(stl_file *stl) {
-  stl->error = 0;
-}
-
-void
-stl_exit_on_error(stl_file *stl) {
-  if (!stl->error) return;
-  stl->error = 0;
-  stl_close(stl);
-  exit(1);
-}
-
-int
-stl_get_error(stl_file *stl) {
-  return stl->error;
+  	fprintf(fp, "0\nENDSEC\n0\nEOF\n");
+  	fclose(fp);
+  	return true;
 }
diff --git a/src/admesh/stlinit.cpp b/src/admesh/stlinit.cpp
index 911f4f5e8..a328baa75 100644
--- a/src/admesh/stlinit.cpp
+++ b/src/admesh/stlinit.cpp
@@ -26,6 +26,7 @@
 #include <math.h>
 #include <assert.h>
 
+#include <boost/log/trivial.hpp>
 #include <boost/nowide/cstdio.hpp>
 #include <boost/detail/endian.hpp>
 
@@ -35,351 +36,236 @@
 #error "SEEK_SET not defined"
 #endif
 
-void
-stl_open(stl_file *stl, const char *file) {
-  stl_initialize(stl);
-  stl_count_facets(stl, file);
-  stl_allocate(stl);
-  stl_read(stl, 0, true);
-  if (stl->fp != nullptr) {
-	  fclose(stl->fp);
-	  stl->fp = nullptr;
-  }
+static FILE* stl_open_count_facets(stl_file *stl, const char *file) 
+{
+  	// Open the file in binary mode first.
+  	FILE *fp = boost::nowide::fopen(file, "rb");
+  	if (fp == nullptr) {
+		BOOST_LOG_TRIVIAL(error) << "stl_open_count_facets: Couldn't open " << file << " for reading";
+    	return nullptr;
+  	}
+  	// Find size of file.
+  	fseek(fp, 0, SEEK_END);
+  	long file_size = ftell(fp);
+
+  	// Check for binary or ASCII file.
+  	fseek(fp, HEADER_SIZE, SEEK_SET);
+	unsigned char chtest[128];
+  	if (! fread(chtest, sizeof(chtest), 1, fp)) {
+		BOOST_LOG_TRIVIAL(error) << "stl_open_count_facets: The input is an empty file: " << file;
+    	fclose(fp);
+    	return nullptr;
+  	}
+  	stl->stats.type = ascii;
+  	for (size_t s = 0; s < sizeof(chtest); s++) {
+    	if (chtest[s] > 127) {
+      		stl->stats.type = binary;
+      		break;
+    	}
+  	}
+  	rewind(fp);
+
+  	uint32_t num_facets = 0;
+
+  	// Get the header and the number of facets in the .STL file.
+  	// If the .STL file is binary, then do the following:
+  	if (stl->stats.type == binary) {
+    	// Test if the STL file has the right size.
+    	if (((file_size - HEADER_SIZE) % SIZEOF_STL_FACET != 0) || (file_size < STL_MIN_FILE_SIZE)) {
+			BOOST_LOG_TRIVIAL(error) << "stl_open_count_facets: The file " << file << " has the wrong size.";
+      		fclose(fp);
+      		return nullptr;
+    	}
+    	num_facets = (file_size - HEADER_SIZE) / SIZEOF_STL_FACET;
+
+    	// Read the header.
+    	if (fread(stl->stats.header, LABEL_SIZE, 1, fp) > 79)
+      		stl->stats.header[80] = '\0';
+
+    	// Read the int following the header.  This should contain # of facets.
+	  	uint32_t header_num_facets;
+    	bool header_num_faces_read = fread(&header_num_facets, sizeof(uint32_t), 1, fp) != 0;
+#ifndef BOOST_LITTLE_ENDIAN
+    	// Convert from little endian to big endian.
+    	stl_internal_reverse_quads((char*)&header_num_facets, 4);
+#endif /* BOOST_LITTLE_ENDIAN */
+    	if (! header_num_faces_read || num_facets != header_num_facets)
+			BOOST_LOG_TRIVIAL(info) << "stl_open_count_facets: Warning: File size doesn't match number of facets in the header: " << file;
+  	}
+  	// Otherwise, if the .STL file is ASCII, then do the following:
+  	else
+  	{
+    	// Reopen the file in text mode (for getting correct newlines on Windows)
+    	// fix to silence a warning about unused return value.
+    	// obviously if it fails we have problems....
+    	fp = boost::nowide::freopen(file, "r", fp);
+
+		// do another null check to be safe
+    	if (fp == nullptr) {
+			BOOST_LOG_TRIVIAL(error) << "stl_open_count_facets: Couldn't open " << file << " for reading";
+      		fclose(fp);
+      		return nullptr;
+    	}
+    
+    	// Find the number of facets.
+		char linebuf[100];
+		int num_lines = 1;
+		while (fgets(linebuf, 100, fp) != nullptr) {
+		    // Don't count short lines.
+		    if (strlen(linebuf) <= 4)
+		    	continue;
+		    // Skip solid/endsolid lines as broken STL file generators may put several of them.
+		    if (strncmp(linebuf, "solid", 5) == 0 || strncmp(linebuf, "endsolid", 8) == 0)
+		    	continue;
+		    ++ num_lines;
+		}
+
+    	rewind(fp);
+    
+    	// Get the header.
+		int i = 0;
+    	for (; i < 80 && (stl->stats.header[i] = getc(fp)) != '\n'; ++ i) ;
+    	stl->stats.header[i] = '\0'; // Lose the '\n'
+    	stl->stats.header[80] = '\0';
+
+    	num_facets = num_lines / ASCII_LINES_PER_FACET;
+  	}
+
+  	stl->stats.number_of_facets += num_facets;
+  	stl->stats.original_num_facets = stl->stats.number_of_facets;
+  	return fp;
 }
 
-void
-stl_initialize(stl_file *stl) {
-  memset(stl, 0, sizeof(stl_file));
-  stl->stats.volume = -1.0;
+/* Reads the contents of the file pointed to by fp into the stl structure,
+   starting at facet first_facet.  The second argument says if it's our first
+   time running this for the stl and therefore we should reset our max and min stats. */
+static bool stl_read(stl_file *stl, FILE *fp, int first_facet, bool first)
+{
+	if (stl->stats.type == binary)
+    	fseek(fp, HEADER_SIZE, SEEK_SET);
+  	else
+    	rewind(fp);
+
+  	char normal_buf[3][32];
+  	for (uint32_t i = first_facet; i < stl->stats.number_of_facets; ++ i) {
+  	  	stl_facet facet;
+
+    	if (stl->stats.type == binary) {
+      		// Read a single facet from a binary .STL file. We assume little-endian architecture!
+      		if (fread(&facet, 1, SIZEOF_STL_FACET, fp) != SIZEOF_STL_FACET)
+      			return false;
+#ifndef BOOST_LITTLE_ENDIAN
+      		// Convert the loaded little endian data to big endian.
+      		stl_internal_reverse_quads((char*)&facet, 48);
+#endif /* BOOST_LITTLE_ENDIAN */
+    	} else {
+			// Read a single facet from an ASCII .STL file
+			// skip solid/endsolid
+			// (in this order, otherwise it won't work when they are paired in the middle of a file)
+			fscanf(fp, "endsolid%*[^\n]\n");
+			fscanf(fp, "solid%*[^\n]\n");  // name might contain spaces so %*s doesn't work and it also can be empty (just "solid")
+			// Leading space in the fscanf format skips all leading white spaces including numerous new lines and tabs.
+			int res_normal     = fscanf(fp, " facet normal %31s %31s %31s", normal_buf[0], normal_buf[1], normal_buf[2]);
+			assert(res_normal == 3);
+			int res_outer_loop = fscanf(fp, " outer loop");
+			assert(res_outer_loop == 0);
+			int res_vertex1    = fscanf(fp, " vertex %f %f %f", &facet.vertex[0](0), &facet.vertex[0](1), &facet.vertex[0](2));
+			assert(res_vertex1 == 3);
+			int res_vertex2    = fscanf(fp, " vertex %f %f %f", &facet.vertex[1](0), &facet.vertex[1](1), &facet.vertex[1](2));
+			assert(res_vertex2 == 3);
+			int res_vertex3    = fscanf(fp, " vertex %f %f %f", &facet.vertex[2](0), &facet.vertex[2](1), &facet.vertex[2](2));
+			assert(res_vertex3 == 3);
+			int res_endloop    = fscanf(fp, " endloop");
+			assert(res_endloop == 0);
+			// There is a leading and trailing white space around endfacet to eat up all leading and trailing white spaces including numerous tabs and new lines.
+			int res_endfacet   = fscanf(fp, " endfacet ");
+			if (res_normal != 3 || res_outer_loop != 0 || res_vertex1 != 3 || res_vertex2 != 3 || res_vertex3 != 3 || res_endloop != 0 || res_endfacet != 0) {
+				BOOST_LOG_TRIVIAL(error) << "Something is syntactically very wrong with this ASCII STL! ";
+				return false;
+			}
+
+			// The facet normal has been parsed as a single string as to workaround for not a numbers in the normal definition.
+			if (sscanf(normal_buf[0], "%f", &facet.normal(0)) != 1 ||
+			    sscanf(normal_buf[1], "%f", &facet.normal(1)) != 1 ||
+			    sscanf(normal_buf[2], "%f", &facet.normal(2)) != 1) {
+			    // Normal was mangled. Maybe denormals or "not a number" were stored?
+			  	// Just reset the normal and silently ignore it.
+			  	memset(&facet.normal, 0, sizeof(facet.normal));
+			}
+		}
+
+#if 0
+		// Report close to zero vertex coordinates. Due to the nature of the floating point numbers,
+		// close to zero values may be represented with singificantly higher precision than the rest of the vertices.
+		// It may be worth to round these numbers to zero during loading to reduce the number of errors reported
+		// during the STL import.
+		for (size_t j = 0; j < 3; ++ j) {
+		if (facet.vertex[j](0) > -1e-12f && facet.vertex[j](0) < 1e-12f)
+		    printf("stl_read: facet %d(0) = %e\r\n", j, facet.vertex[j](0));
+		if (facet.vertex[j](1) > -1e-12f && facet.vertex[j](1) < 1e-12f)
+		    printf("stl_read: facet %d(1) = %e\r\n", j, facet.vertex[j](1));
+		if (facet.vertex[j](2) > -1e-12f && facet.vertex[j](2) < 1e-12f)
+		    printf("stl_read: facet %d(2) = %e\r\n", j, facet.vertex[j](2));
+		}
+#endif
+
+		// Write the facet into memory.
+		stl->facet_start[i] = facet;
+		stl_facet_stats(stl, facet, first);
+  	}
+  
+  	stl->stats.size = stl->stats.max - stl->stats.min;
+  	stl->stats.bounding_diameter = stl->stats.size.norm();
+  	return true;
+}
+
+bool stl_open(stl_file *stl, const char *file)
+{
+	stl->clear();
+	FILE *fp = stl_open_count_facets(stl, file);
+	if (fp == nullptr)
+		return false;
+	stl_allocate(stl);
+	bool result = stl_read(stl, fp, 0, true);
+  	fclose(fp);
+  	return result;
 }
 
 #ifndef BOOST_LITTLE_ENDIAN
 extern void stl_internal_reverse_quads(char *buf, size_t cnt);
 #endif /* BOOST_LITTLE_ENDIAN */
 
-void
-stl_count_facets(stl_file *stl, const char *file) {
-  long           file_size;
-  uint32_t       header_num_facets;
-  uint32_t       num_facets;
-  int            i;
-  size_t         s;
-  unsigned char  chtest[128];
-  int            num_lines = 1;
-  char           *error_msg;
-
-  if (stl->error) return;
-
-  /* Open the file in binary mode first */
-  stl->fp = boost::nowide::fopen(file, "rb");
-  if(stl->fp == NULL) {
-    error_msg = (char*)
-                malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
-    sprintf(error_msg, "stl_initialize: Couldn't open %s for reading",
-            file);
-    perror(error_msg);
-    free(error_msg);
-    stl->error = 1;
-    return;
-  }
-  /* Find size of file */
-  fseek(stl->fp, 0, SEEK_END);
-  file_size = ftell(stl->fp);
-
-  /* Check for binary or ASCII file */
-  fseek(stl->fp, HEADER_SIZE, SEEK_SET);
-  if (!fread(chtest, sizeof(chtest), 1, stl->fp)) {
-    perror("The input is an empty file");
-    stl->error = 1;
-    return;
-  }
-  stl->stats.type = ascii;
-  for(s = 0; s < sizeof(chtest); s++) {
-    if(chtest[s] > 127) {
-      stl->stats.type = binary;
-      break;
-    }
-  }
-  rewind(stl->fp);
-
-  /* Get the header and the number of facets in the .STL file */
-  /* If the .STL file is binary, then do the following */
-  if(stl->stats.type == binary) {
-    /* Test if the STL file has the right size  */
-    if(((file_size - HEADER_SIZE) % SIZEOF_STL_FACET != 0)
-        || (file_size < STL_MIN_FILE_SIZE)) {
-      fprintf(stderr, "The file %s has the wrong size.\n", file);
-      stl->error = 1;
-      return;
-    }
-    num_facets = (file_size - HEADER_SIZE) / SIZEOF_STL_FACET;
-
-    /* Read the header */
-    if (fread(stl->stats.header, LABEL_SIZE, 1, stl->fp) > 79) {
-      stl->stats.header[80] = '\0';
-    }
-
-    /* Read the int following the header.  This should contain # of facets */
-    bool header_num_faces_read = fread(&header_num_facets, sizeof(uint32_t), 1, stl->fp) != 0;
-#ifndef BOOST_LITTLE_ENDIAN
-    // Convert from little endian to big endian.
-    stl_internal_reverse_quads((char*)&header_num_facets, 4);
-#endif /* BOOST_LITTLE_ENDIAN */
-    if (! header_num_faces_read || num_facets != header_num_facets) {
-      fprintf(stderr,
-              "Warning: File size doesn't match number of facets in the header\n");
-    }
-  }
-  /* Otherwise, if the .STL file is ASCII, then do the following */
-  else {
-    /* Reopen the file in text mode (for getting correct newlines on Windows) */
-    // fix to silence a warning about unused return value.
-    // obviously if it fails we have problems....
-    stl->fp = boost::nowide::freopen(file, "r", stl->fp);
-
-    // do another null check to be safe
-    if(stl->fp == NULL) {
-      error_msg = (char*)
-        malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
-      sprintf(error_msg, "stl_initialize: Couldn't open %s for reading",
-          file);
-      perror(error_msg);
-      free(error_msg);
-      stl->error = 1;
-      return;
-    }
-    
-    /* Find the number of facets */
-    char linebuf[100];
-    while (fgets(linebuf, 100, stl->fp) != NULL) {
-        /* don't count short lines */
-        if (strlen(linebuf) <= 4) continue;
-        
-        /* skip solid/endsolid lines as broken STL file generators may put several of them */
-        if (strncmp(linebuf, "solid", 5) == 0 || strncmp(linebuf, "endsolid", 8) == 0) continue;
-        
-        ++num_lines;
-    }
-    
-    rewind(stl->fp);
-    
-    /* Get the header */
-    for(i = 0;
-        (i < 80) && (stl->stats.header[i] = getc(stl->fp)) != '\n'; i++);
-    stl->stats.header[i] = '\0'; /* Lose the '\n' */
-    stl->stats.header[80] = '\0';
-
-    num_facets = num_lines / ASCII_LINES_PER_FACET;
-  }
-  stl->stats.number_of_facets += num_facets;
-  stl->stats.original_num_facets = stl->stats.number_of_facets;
+void stl_allocate(stl_file *stl) 
+{
+  	//  Allocate memory for the entire .STL file.
+  	stl->facet_start.assign(stl->stats.number_of_facets, stl_facet());
+  	// Allocate memory for the neighbors list.
+  	stl->neighbors_start.assign(stl->stats.number_of_facets, stl_neighbors());
 }
 
-void
-stl_allocate(stl_file *stl) {
-  if (stl->error) return;
-
-  /*  Allocate memory for the entire .STL file */
-  stl->facet_start = (stl_facet*)calloc(stl->stats.number_of_facets,
-                                        sizeof(stl_facet));
-  if(stl->facet_start == NULL) perror("stl_initialize");
-  stl->stats.facets_malloced = stl->stats.number_of_facets;
-
-  /* Allocate memory for the neighbors list */
-  stl->neighbors_start = (stl_neighbors*)
-                         calloc(stl->stats.number_of_facets, sizeof(stl_neighbors));
-  if(stl->facet_start == NULL) perror("stl_initialize");
-}
-
-void
-stl_open_merge(stl_file *stl, char *file_to_merge) {
-  int num_facets_so_far;
-  stl_type origStlType;
-  FILE *origFp;
-  stl_file stl_to_merge;
-
-  if (stl->error) return;
-
-  /* Record how many facets we have so far from the first file.  We will start putting
-     facets in the next position.  Since we're 0-indexed, it'l be the same position. */
-  num_facets_so_far = stl->stats.number_of_facets;
-
-  /* Record the file type we started with: */
-  origStlType=stl->stats.type;
-  /* Record the file pointer too: */
-  origFp=stl->fp;
-
-  /* Initialize the sturucture with zero stats, header info and sizes: */
-  stl_initialize(&stl_to_merge);
-  stl_count_facets(&stl_to_merge, file_to_merge);
-
-  /* Copy what we need to into stl so that we can read the file_to_merge directly into it
-     using stl_read:  Save the rest of the valuable info: */
-  stl->stats.type=stl_to_merge.stats.type;
-  stl->fp=stl_to_merge.fp;
-
-  /* Add the number of facets we already have in stl with what we we found in stl_to_merge but
-     haven't read yet. */
-  stl->stats.number_of_facets=num_facets_so_far+stl_to_merge.stats.number_of_facets;
-
-  /* Allocate enough room for stl->stats.number_of_facets facets and neighbors: */
-  stl_reallocate(stl);
-
-  /* Read the file to merge directly into stl, adding it to what we have already.
-     Start at num_facets_so_far, the index to the first unused facet.  Also say
-     that this isn't our first time so we should augment stats like min and max
-     instead of erasing them. */
-  stl_read(stl, num_facets_so_far, false);
-
-  /* Restore the stl information we overwrote (for stl_read) so that it still accurately
-     reflects the subject part: */
-  stl->stats.type=origStlType;
-  stl->fp=origFp;
-}
-
-extern void
-stl_reallocate(stl_file *stl) {
-  if (stl->error) return;
-  /*  Reallocate more memory for the .STL file(s) */
-  stl->facet_start = (stl_facet*)realloc(stl->facet_start, stl->stats.number_of_facets *
-                                         sizeof(stl_facet));
-  if(stl->facet_start == NULL) perror("stl_initialize");
-  stl->stats.facets_malloced = stl->stats.number_of_facets;
-
-  /* Reallocate more memory for the neighbors list */
-  stl->neighbors_start = (stl_neighbors*)
-                         realloc(stl->neighbors_start, stl->stats.number_of_facets *
-                                 sizeof(stl_neighbors));
-  if(stl->facet_start == NULL) perror("stl_initialize");
-}
-
-
-/* Reads the contents of the file pointed to by stl->fp into the stl structure,
-   starting at facet first_facet.  The second argument says if it's our first
-   time running this for the stl and therefore we should reset our max and min stats. */
-void stl_read(stl_file *stl, int first_facet, bool first) {
-  stl_facet facet;
-
-  if (stl->error) return;
-
-  if(stl->stats.type == binary) {
-    fseek(stl->fp, HEADER_SIZE, SEEK_SET);
-  } else {
-    rewind(stl->fp);
-  }
-
-  char normal_buf[3][32];
-  for(uint32_t i = first_facet; i < stl->stats.number_of_facets; i++) {
-    if(stl->stats.type == binary)
-      /* Read a single facet from a binary .STL file */
-    {
-      /* we assume little-endian architecture! */
-      if (fread(&facet, 1, SIZEOF_STL_FACET, stl->fp) != SIZEOF_STL_FACET) {
-        stl->error = 1;
-        return;
-      }
-#ifndef BOOST_LITTLE_ENDIAN
-      // Convert the loaded little endian data to big endian.
-      stl_internal_reverse_quads((char*)&facet, 48);
-#endif /* BOOST_LITTLE_ENDIAN */
-    } else
-      /* Read a single facet from an ASCII .STL file */
-    {
-      // skip solid/endsolid
-      // (in this order, otherwise it won't work when they are paired in the middle of a file)
-      fscanf(stl->fp, "endsolid%*[^\n]\n");
-      fscanf(stl->fp, "solid%*[^\n]\n");  // name might contain spaces so %*s doesn't work and it also can be empty (just "solid")
-      // Leading space in the fscanf format skips all leading white spaces including numerous new lines and tabs.
-      int res_normal     = fscanf(stl->fp, " facet normal %31s %31s %31s", normal_buf[0], normal_buf[1], normal_buf[2]);
-      assert(res_normal == 3);
-      int res_outer_loop = fscanf(stl->fp, " outer loop");
-      assert(res_outer_loop == 0);
-      int res_vertex1    = fscanf(stl->fp, " vertex %f %f %f", &facet.vertex[0](0), &facet.vertex[0](1), &facet.vertex[0](2));
-      assert(res_vertex1 == 3);
-      int res_vertex2    = fscanf(stl->fp, " vertex %f %f %f", &facet.vertex[1](0), &facet.vertex[1](1), &facet.vertex[1](2));
-      assert(res_vertex2 == 3);
-      int res_vertex3    = fscanf(stl->fp, " vertex %f %f %f", &facet.vertex[2](0), &facet.vertex[2](1), &facet.vertex[2](2));
-      assert(res_vertex3 == 3);
-      int res_endloop    = fscanf(stl->fp, " endloop");
-      assert(res_endloop == 0);
-      // There is a leading and trailing white space around endfacet to eat up all leading and trailing white spaces including numerous tabs and new lines.
-      int res_endfacet   = fscanf(stl->fp, " endfacet ");
-      if (res_normal != 3 || res_outer_loop != 0 || res_vertex1 != 3 || res_vertex2 != 3 || res_vertex3 != 3 || res_endloop != 0 || res_endfacet != 0) {
-        perror("Something is syntactically very wrong with this ASCII STL!");
-        stl->error = 1;
-        return;
-      }
-
-      // The facet normal has been parsed as a single string as to workaround for not a numbers in the normal definition.
-	  if (sscanf(normal_buf[0], "%f", &facet.normal(0)) != 1 ||
-		  sscanf(normal_buf[1], "%f", &facet.normal(1)) != 1 ||
-		  sscanf(normal_buf[2], "%f", &facet.normal(2)) != 1) {
-		  // Normal was mangled. Maybe denormals or "not a number" were stored?
-		  // Just reset the normal and silently ignore it.
-		  memset(&facet.normal, 0, sizeof(facet.normal));
-	  }
-    }
-
-#if 0
-      // Report close to zero vertex coordinates. Due to the nature of the floating point numbers,
-      // close to zero values may be represented with singificantly higher precision than the rest of the vertices.
-      // It may be worth to round these numbers to zero during loading to reduce the number of errors reported
-      // during the STL import.
-      for (size_t j = 0; j < 3; ++ j) {
-        if (facet.vertex[j](0) > -1e-12f && facet.vertex[j](0) < 1e-12f)
-            printf("stl_read: facet %d(0) = %e\r\n", j, facet.vertex[j](0));
-        if (facet.vertex[j](1) > -1e-12f && facet.vertex[j](1) < 1e-12f)
-            printf("stl_read: facet %d(1) = %e\r\n", j, facet.vertex[j](1));
-        if (facet.vertex[j](2) > -1e-12f && facet.vertex[j](2) < 1e-12f)
-            printf("stl_read: facet %d(2) = %e\r\n", j, facet.vertex[j](2));
-      }
-#endif
-
-    /* Write the facet into memory. */
-    stl->facet_start[i] = facet;
-    stl_facet_stats(stl, facet, first);
-  }
-  stl->stats.size = stl->stats.max - stl->stats.min;
-  stl->stats.bounding_diameter = stl->stats.size.norm();
+void stl_reallocate(stl_file *stl) 
+{
+	stl->facet_start.resize(stl->stats.number_of_facets);
+	stl->neighbors_start.resize(stl->stats.number_of_facets);
 }
 
 void stl_facet_stats(stl_file *stl, stl_facet facet, bool &first)
 {
-  if (stl->error)
-  	return;
+	// While we are going through all of the facets, let's find the
+	// maximum and minimum values for x, y, and z
 
-  // While we are going through all of the facets, let's find the
-  // maximum and minimum values for x, y, and z
+	if (first) {
+		// Initialize the max and min values the first time through
+		stl->stats.min = facet.vertex[0];
+		stl->stats.max = facet.vertex[0];
+		stl_vertex diff = (facet.vertex[1] - facet.vertex[0]).cwiseAbs();
+		stl->stats.shortest_edge = std::max(diff(0), std::max(diff(1), diff(2)));
+		first = false;
+	}
 
-  if (first) {
-	// Initialize the max and min values the first time through
-    stl->stats.min = facet.vertex[0];
-    stl->stats.max = facet.vertex[0];
-    stl_vertex diff = (facet.vertex[1] - facet.vertex[0]).cwiseAbs();
-    stl->stats.shortest_edge = std::max(diff(0), std::max(diff(1), diff(2)));
-    first = false;
-  }
-
-  // Now find the max and min values.
-  for (size_t i = 0; i < 3; ++ i) {
-  	stl->stats.min = stl->stats.min.cwiseMin(facet.vertex[i]);
-  	stl->stats.max = stl->stats.max.cwiseMax(facet.vertex[i]);
-  }
-}
-
-void stl_close(stl_file *stl)
-{
-	assert(stl->fp == nullptr);
-	assert(stl->heads == nullptr);
-	assert(stl->tail == nullptr);
-
-	if (stl->facet_start != NULL)
-		free(stl->facet_start);
-	if (stl->neighbors_start != NULL)
-		free(stl->neighbors_start);
-	if (stl->v_indices != NULL)
-		free(stl->v_indices);
-	if (stl->v_shared != NULL)
-		free(stl->v_shared);
-	memset(stl, 0, sizeof(stl_file));
+	// Now find the max and min values.
+	for (size_t i = 0; i < 3; ++ i) {
+		stl->stats.min = stl->stats.min.cwiseMin(facet.vertex[i]);
+		stl->stats.max = stl->stats.max.cwiseMax(facet.vertex[i]);
+	}
 }
diff --git a/src/admesh/util.cpp b/src/admesh/util.cpp
index 305a58e22..029e44a28 100644
--- a/src/admesh/util.cpp
+++ b/src/admesh/util.cpp
@@ -25,435 +25,375 @@
 #include <string.h>
 #include <math.h>
 
+#include <boost/log/trivial.hpp>
+
 #include "stl.h"
 
-static void stl_rotate(float *x, float *y, const double c, const double s);
-static float get_area(stl_facet *facet);
-static float get_volume(stl_file *stl);
+void stl_verify_neighbors(stl_file *stl)
+{
+	stl->stats.backwards_edges = 0;
 
-
-void
-stl_verify_neighbors(stl_file *stl) {
-  int i;
-  int j;
-  stl_edge edge_a;
-  stl_edge edge_b;
-  int neighbor;
-  int vnot;
-
-  if (stl->error) return;
-
-  stl->stats.backwards_edges = 0;
-
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    for(j = 0; j < 3; j++) {
-      edge_a.p1 = stl->facet_start[i].vertex[j];
-      edge_a.p2 = stl->facet_start[i].vertex[(j + 1) % 3];
-      neighbor = stl->neighbors_start[i].neighbor[j];
-      vnot = stl->neighbors_start[i].which_vertex_not[j];
-
-      if(neighbor == -1)
-        continue;		/* this edge has no neighbor... Continue. */
-      if(vnot < 3) {
-        edge_b.p1 = stl->facet_start[neighbor].vertex[(vnot + 2) % 3];
-        edge_b.p2 = stl->facet_start[neighbor].vertex[(vnot + 1) % 3];
-      } else {
-        stl->stats.backwards_edges += 1;
-        edge_b.p1 = stl->facet_start[neighbor].vertex[(vnot + 1) % 3];
-        edge_b.p2 = stl->facet_start[neighbor].vertex[(vnot + 2) % 3];
-      }
-      if (edge_a.p1 != edge_b.p1 || edge_a.p2 != edge_b.p2) {
-        /* These edges should match but they don't.  Print results. */
-        printf("edge %d of facet %d doesn't match edge %d of facet %d\n",
-               j, i, vnot + 1, neighbor);
-        stl_write_facet(stl, (char*)"first facet", i);
-        stl_write_facet(stl, (char*)"second facet", neighbor);
-      }
-    }
-  }
+	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+		for (int j = 0; j < 3; ++ j) {
+			struct stl_edge {
+				stl_vertex p1;
+				stl_vertex p2;
+				int        facet_number;
+			};
+			stl_edge edge_a;
+			edge_a.p1 = stl->facet_start[i].vertex[j];
+			edge_a.p2 = stl->facet_start[i].vertex[(j + 1) % 3];
+			int neighbor = stl->neighbors_start[i].neighbor[j];
+			if (neighbor == -1)
+				continue; // this edge has no neighbor... Continue.
+			int vnot = stl->neighbors_start[i].which_vertex_not[j];
+			stl_edge edge_b;
+			if (vnot < 3) {
+				edge_b.p1 = stl->facet_start[neighbor].vertex[(vnot + 2) % 3];
+				edge_b.p2 = stl->facet_start[neighbor].vertex[(vnot + 1) % 3];
+			} else {
+				stl->stats.backwards_edges += 1;
+				edge_b.p1 = stl->facet_start[neighbor].vertex[(vnot + 1) % 3];
+				edge_b.p2 = stl->facet_start[neighbor].vertex[(vnot + 2) % 3];
+			}
+			if (edge_a.p1 != edge_b.p1 || edge_a.p2 != edge_b.p2) {
+				// These edges should match but they don't.  Print results.
+				BOOST_LOG_TRIVIAL(info) << "edge " << j << " of facet " << i << " doesn't match edge " << (vnot + 1) << " of facet " << neighbor;
+				stl_write_facet(stl, (char*)"first facet", i);
+				stl_write_facet(stl, (char*)"second facet", neighbor);
+			}
+		}
+	}
 }
 
 void stl_translate(stl_file *stl, float x, float y, float z)
 {
-  if (stl->error)
-  	return;
-
-  stl_vertex new_min(x, y, z);
-  stl_vertex shift = new_min - stl->stats.min;
-  for (int i = 0; i < stl->stats.number_of_facets; ++ i)
-    for (int j = 0; j < 3; ++ j)
-      stl->facet_start[i].vertex[j] += shift;
-  stl->stats.min = new_min;
-  stl->stats.max += shift;
-  stl_invalidate_shared_vertices(stl);
+	stl_vertex new_min(x, y, z);
+	stl_vertex shift = new_min - stl->stats.min;
+	for (int i = 0; i < stl->stats.number_of_facets; ++ i)
+		for (int j = 0; j < 3; ++ j)
+	  		stl->facet_start[i].vertex[j] += shift;
+	stl->stats.min = new_min;
+	stl->stats.max += shift;
 }
 
 /* Translates the stl by x,y,z, relatively from wherever it is currently */
 void stl_translate_relative(stl_file *stl, float x, float y, float z)
 {
-  if (stl->error)
-  	return;
-
-  stl_vertex shift(x, y, z);
-  for (int i = 0; i < stl->stats.number_of_facets; ++ i)
-    for (int j = 0; j < 3; ++ j)
-      stl->facet_start[i].vertex[j] += shift;
-  stl->stats.min += shift;
-  stl->stats.max += shift;
-  stl_invalidate_shared_vertices(stl);
+	stl_vertex shift(x, y, z);
+	for (int i = 0; i < stl->stats.number_of_facets; ++ i)
+		for (int j = 0; j < 3; ++ j)
+	  		stl->facet_start[i].vertex[j] += shift;
+	stl->stats.min += shift;
+	stl->stats.max += shift;
 }
 
 void stl_scale_versor(stl_file *stl, const stl_vertex &versor)
 {
-  if (stl->error)
-  	return;
-
-  // Scale extents.
-  auto s = versor.array();
-  stl->stats.min.array() *= s;
-  stl->stats.max.array() *= s;
-  // Scale size.
-  stl->stats.size.array() *= s;
-  // Scale volume.
-  if (stl->stats.volume > 0.0)
-    stl->stats.volume *= versor(0) * versor(1) * versor(2);
-  // Scale the mesh.
-  for (int i = 0; i < stl->stats.number_of_facets; ++ i)
-    for (int j = 0; j < 3; ++ j)
-      stl->facet_start[i].vertex[j].array() *= s;
-  stl_invalidate_shared_vertices(stl);
+	// Scale extents.
+	auto s = versor.array();
+	stl->stats.min.array() *= s;
+	stl->stats.max.array() *= s;
+	// Scale size.
+	stl->stats.size.array() *= s;
+	// Scale volume.
+	if (stl->stats.volume > 0.0)
+		stl->stats.volume *= versor(0) * versor(1) * versor(2);
+	// Scale the mesh.
+	for (int i = 0; i < stl->stats.number_of_facets; ++ i)
+		for (int j = 0; j < 3; ++ j)
+	  		stl->facet_start[i].vertex[j].array() *= s;
 }
 
 static void calculate_normals(stl_file *stl) 
 {
-  if (stl->error)
-  	return;
-
-  stl_normal normal;
-  for(uint32_t i = 0; i < stl->stats.number_of_facets; i++) {
-    stl_calculate_normal(normal, &stl->facet_start[i]);
-    stl_normalize_vector(normal);
-    stl->facet_start[i].normal = normal;
-  }
+	stl_normal normal;
+	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+		stl_calculate_normal(normal, &stl->facet_start[i]);
+		stl_normalize_vector(normal);
+		stl->facet_start[i].normal = normal;
+	}
 }
 
-void
-stl_rotate_x(stl_file *stl, float angle) {
-  int i;
-  int j;
-  double radian_angle = (angle / 180.0) * M_PI;
-  double c = cos(radian_angle);
-  double s = sin(radian_angle);
-
-  if (stl->error) return;
-
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    for(j = 0; j < 3; j++) {
-      stl_rotate(&stl->facet_start[i].vertex[j](1),
-                 &stl->facet_start[i].vertex[j](2), c, s);
-    }
-  }
-  stl_get_size(stl);
-  calculate_normals(stl);
+static inline void rotate_point_2d(float &x, float &y, const double c, const double s)
+{
+	double xold = x;
+	double yold = y;
+	x = float(c * xold - s * yold);
+	y = float(s * xold + c * yold);
 }
 
-void
-stl_rotate_y(stl_file *stl, float angle) {
-  int i;
-  int j;
-  double radian_angle = (angle / 180.0) * M_PI;
-  double c = cos(radian_angle);
-  double s = sin(radian_angle);
-
-  if (stl->error) return;
-
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    for(j = 0; j < 3; j++) {
-      stl_rotate(&stl->facet_start[i].vertex[j](2),
-                 &stl->facet_start[i].vertex[j](0), c, s);
-    }
-  }
-  stl_get_size(stl);
-  calculate_normals(stl);
+void stl_rotate_x(stl_file *stl, float angle)
+{
+	double radian_angle = (angle / 180.0) * M_PI;
+	double c = cos(radian_angle);
+	double s = sin(radian_angle);
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i)
+    	for (int j = 0; j < 3; ++ j)
+      		rotate_point_2d(stl->facet_start[i].vertex[j](1), stl->facet_start[i].vertex[j](2), c, s);
+  	stl_get_size(stl);
+  	calculate_normals(stl);
 }
 
-void
-stl_rotate_z(stl_file *stl, float angle) {
-  int i;
-  int j;
-  double radian_angle = (angle / 180.0) * M_PI;
-  double c = cos(radian_angle);
-  double s = sin(radian_angle);
-
-  if (stl->error) return;
-
-  for(i = 0; i < stl->stats.number_of_facets; i++) {
-    for(j = 0; j < 3; j++) {
-      stl_rotate(&stl->facet_start[i].vertex[j](0),
-                 &stl->facet_start[i].vertex[j](1), c, s);
-    }
-  }
-  stl_get_size(stl);
-  calculate_normals(stl);
+void stl_rotate_y(stl_file *stl, float angle)
+{
+	double radian_angle = (angle / 180.0) * M_PI;
+	double c = cos(radian_angle);
+	double s = sin(radian_angle);
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i)
+    	for (int j = 0; j < 3; ++ j)
+			rotate_point_2d(stl->facet_start[i].vertex[j](2), stl->facet_start[i].vertex[j](0), c, s);
+  	stl_get_size(stl);
+  	calculate_normals(stl);
 }
 
+void stl_rotate_z(stl_file *stl, float angle)
+{
+	double radian_angle = (angle / 180.0) * M_PI;
+	double c = cos(radian_angle);
+	double s = sin(radian_angle);
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i)
+    	for (int j = 0; j < 3; ++ j)
+      		rotate_point_2d(stl->facet_start[i].vertex[j](0), stl->facet_start[i].vertex[j](1), c, s);
+  	stl_get_size(stl);
+  	calculate_normals(stl);
+}
 
+void its_rotate_x(indexed_triangle_set &its, float angle)
+{
+	double radian_angle = (angle / 180.0) * M_PI;
+	double c = cos(radian_angle);
+	double s = sin(radian_angle);
+	for (stl_vertex &v : its.vertices)
+		rotate_point_2d(v(1), v(2), c, s);
+}
 
-static void
-stl_rotate(float *x, float *y, const double c, const double s) {
-  double xold = *x;
-  double yold = *y;
-  *x = float(c * xold - s * yold);
-  *y = float(s * xold + c * yold);
+void its_rotate_y(indexed_triangle_set& its, float angle)
+{
+	double radian_angle = (angle / 180.0) * M_PI;
+	double c = cos(radian_angle);
+	double s = sin(radian_angle);
+	for (stl_vertex& v : its.vertices)
+		rotate_point_2d(v(2), v(0), c, s);
+}
+
+void its_rotate_z(indexed_triangle_set& its, float angle)
+{
+	double radian_angle = (angle / 180.0) * M_PI;
+	double c = cos(radian_angle);
+	double s = sin(radian_angle);
+	for (stl_vertex& v : its.vertices)
+		rotate_point_2d(v(0), v(1), c, s);
 }
 
 void stl_get_size(stl_file *stl)
 {
-  if (stl->error || stl->stats.number_of_facets == 0)
-  	return;
-  stl->stats.min = stl->facet_start[0].vertex[0];
-  stl->stats.max = stl->stats.min;
-  for (int i = 0; i < stl->stats.number_of_facets; ++ i) {
-  	const stl_facet &face = stl->facet_start[i];
-    for (int j = 0; j < 3; ++ j) {
-      stl->stats.min = stl->stats.min.cwiseMin(face.vertex[j]);
-      stl->stats.max = stl->stats.max.cwiseMax(face.vertex[j]);
-    }
-  }
-  stl->stats.size = stl->stats.max - stl->stats.min;
-  stl->stats.bounding_diameter = stl->stats.size.norm();
+  	if (stl->stats.number_of_facets == 0)
+  		return;
+  	stl->stats.min = stl->facet_start[0].vertex[0];
+  	stl->stats.max = stl->stats.min;
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+  		const stl_facet &face = stl->facet_start[i];
+    	for (int j = 0; j < 3; ++ j) {
+      		stl->stats.min = stl->stats.min.cwiseMin(face.vertex[j]);
+      		stl->stats.max = stl->stats.max.cwiseMax(face.vertex[j]);
+    	}
+  	}
+  	stl->stats.size = stl->stats.max - stl->stats.min;
+  	stl->stats.bounding_diameter = stl->stats.size.norm();
 }
 
 void stl_mirror_xy(stl_file *stl)
 {
-  if (stl->error) 
-  	return;
-
-  for(int i = 0; i < stl->stats.number_of_facets; i++) {
-    for(int j = 0; j < 3; j++) {
-      stl->facet_start[i].vertex[j](2) *= -1.0;
-    }
-  }
-  float temp_size = stl->stats.min(2);
-  stl->stats.min(2) = stl->stats.max(2);
-  stl->stats.max(2) = temp_size;
-  stl->stats.min(2) *= -1.0;
-  stl->stats.max(2) *= -1.0;
-  stl_reverse_all_facets(stl);
-  stl->stats.facets_reversed -= stl->stats.number_of_facets;  /* for not altering stats */
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i)
+    	for (int j = 0; j < 3; ++ j)
+      		stl->facet_start[i].vertex[j](2) *= -1.0;
+	float temp_size = stl->stats.min(2);
+	stl->stats.min(2) = stl->stats.max(2);
+	stl->stats.max(2) = temp_size;
+	stl->stats.min(2) *= -1.0;
+	stl->stats.max(2) *= -1.0;
+	stl_reverse_all_facets(stl);
+	stl->stats.facets_reversed -= stl->stats.number_of_facets;  /* for not altering stats */
 }
 
 void stl_mirror_yz(stl_file *stl)
 {
-  if (stl->error) return;
-
-  for (int i = 0; i < stl->stats.number_of_facets; i++) {
-    for (int j = 0; j < 3; j++) {
-      stl->facet_start[i].vertex[j](0) *= -1.0;
-    }
-  }
-  float temp_size = stl->stats.min(0);
-  stl->stats.min(0) = stl->stats.max(0);
-  stl->stats.max(0) = temp_size;
-  stl->stats.min(0) *= -1.0;
-  stl->stats.max(0) *= -1.0;
-  stl_reverse_all_facets(stl);
-  stl->stats.facets_reversed -= stl->stats.number_of_facets;  /* for not altering stats */
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i)
+    	for (int j = 0; j < 3; j++)
+      		stl->facet_start[i].vertex[j](0) *= -1.0;
+	float temp_size = stl->stats.min(0);
+	stl->stats.min(0) = stl->stats.max(0);
+	stl->stats.max(0) = temp_size;
+	stl->stats.min(0) *= -1.0;
+	stl->stats.max(0) *= -1.0;
+	stl_reverse_all_facets(stl);
+	stl->stats.facets_reversed -= stl->stats.number_of_facets;  /* for not altering stats */
 }
 
 void stl_mirror_xz(stl_file *stl)
 {
-  if (stl->error)
-  	return;
-
-  for (int i = 0; i < stl->stats.number_of_facets; i++) {
-    for (int j = 0; j < 3; j++) {
-      stl->facet_start[i].vertex[j](1) *= -1.0;
-    }
-  }
-  float temp_size = stl->stats.min(1);
-  stl->stats.min(1) = stl->stats.max(1);
-  stl->stats.max(1) = temp_size;
-  stl->stats.min(1) *= -1.0;
-  stl->stats.max(1) *= -1.0;
-  stl_reverse_all_facets(stl);
-  stl->stats.facets_reversed -= stl->stats.number_of_facets;  /* for not altering stats */
-}
-
-static float get_volume(stl_file *stl)
-{
-  if (stl->error)
-  	return 0;
-
-  // Choose a point, any point as the reference.
-  stl_vertex p0 = stl->facet_start[0].vertex[0];
-  float volume = 0.f;
-  for(uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
-    // Do dot product to get distance from point to plane.
-    float height = stl->facet_start[i].normal.dot(stl->facet_start[i].vertex[0] - p0);
-    float area   = get_area(&stl->facet_start[i]);
-    volume += (area * height) / 3.0f;
-  }
-  return volume;
-}
-
-void stl_calculate_volume(stl_file *stl)
-{
-  if (stl->error) return;
-  stl->stats.volume = get_volume(stl);
-  if(stl->stats.volume < 0.0) {
-    stl_reverse_all_facets(stl);
-    stl->stats.volume = -stl->stats.volume;
-  }
+	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i)
+		for (int j = 0; j < 3; ++ j)
+			stl->facet_start[i].vertex[j](1) *= -1.0;
+	float temp_size = stl->stats.min(1);
+	stl->stats.min(1) = stl->stats.max(1);
+	stl->stats.max(1) = temp_size;
+	stl->stats.min(1) *= -1.0;
+	stl->stats.max(1) *= -1.0;
+	stl_reverse_all_facets(stl);
+	stl->stats.facets_reversed -= stl->stats.number_of_facets;  // for not altering stats
 }
 
 static float get_area(stl_facet *facet)
 {
-  /* cast to double before calculating cross product because large coordinates
-     can result in overflowing product
-    (bad area is responsible for bad volume and bad facets reversal) */
-  double cross[3][3];
-  for (int i = 0; i < 3; i++) {
-    cross[i][0]=(((double)facet->vertex[i](1) * (double)facet->vertex[(i + 1) % 3](2)) -
-                 ((double)facet->vertex[i](2) * (double)facet->vertex[(i + 1) % 3](1)));
-    cross[i][1]=(((double)facet->vertex[i](2) * (double)facet->vertex[(i + 1) % 3](0)) -
-                 ((double)facet->vertex[i](0) * (double)facet->vertex[(i + 1) % 3](2)));
-    cross[i][2]=(((double)facet->vertex[i](0) * (double)facet->vertex[(i + 1) % 3](1)) -
-                 ((double)facet->vertex[i](1) * (double)facet->vertex[(i + 1) % 3](0)));
-  }
+	/* cast to double before calculating cross product because large coordinates
+	 can result in overflowing product
+	(bad area is responsible for bad volume and bad facets reversal) */
+	double cross[3][3];
+	for (int i = 0; i < 3; i++) {
+		cross[i][0]=(((double)facet->vertex[i](1) * (double)facet->vertex[(i + 1) % 3](2)) -
+	             	 ((double)facet->vertex[i](2) * (double)facet->vertex[(i + 1) % 3](1)));
+		cross[i][1]=(((double)facet->vertex[i](2) * (double)facet->vertex[(i + 1) % 3](0)) -
+	             	 ((double)facet->vertex[i](0) * (double)facet->vertex[(i + 1) % 3](2)));
+		cross[i][2]=(((double)facet->vertex[i](0) * (double)facet->vertex[(i + 1) % 3](1)) -
+	             	 ((double)facet->vertex[i](1) * (double)facet->vertex[(i + 1) % 3](0)));
+	}
 
-  stl_normal sum;
-  sum(0) = cross[0][0] + cross[1][0] + cross[2][0];
-  sum(1) = cross[0][1] + cross[1][1] + cross[2][1];
-  sum(2) = cross[0][2] + cross[1][2] + cross[2][2];
+	stl_normal sum;
+	sum(0) = cross[0][0] + cross[1][0] + cross[2][0];
+	sum(1) = cross[0][1] + cross[1][1] + cross[2][1];
+	sum(2) = cross[0][2] + cross[1][2] + cross[2][2];
 
-  // This should already be done.  But just in case, let's do it again.
-  //FIXME this is questionable. the "sum" normal should be accurate, while the normal "n" may be calculated with a low accuracy.
-  stl_normal n;
-  stl_calculate_normal(n, facet);
-  stl_normalize_vector(n);
-  return 0.5f * n.dot(sum);
+	// This should already be done.  But just in case, let's do it again.
+	//FIXME this is questionable. the "sum" normal should be accurate, while the normal "n" may be calculated with a low accuracy.
+	stl_normal n;
+	stl_calculate_normal(n, facet);
+	stl_normalize_vector(n);
+	return 0.5f * n.dot(sum);
 }
 
-void stl_repair(stl_file *stl,
-                int fixall_flag,
-                int exact_flag,
-                int tolerance_flag,
-                float tolerance,
-                int increment_flag,
-                float increment,
-                int nearby_flag,
-                int iterations,
-                int remove_unconnected_flag,
-                int fill_holes_flag,
-                int normal_directions_flag,
-                int normal_values_flag,
-                int reverse_all_flag,
-                int verbose_flag) {
-  
-  int i;
-  int last_edges_fixed = 0;
-
-  if (stl->error) return;
-
-  if(exact_flag || fixall_flag || nearby_flag || remove_unconnected_flag
-      || fill_holes_flag || normal_directions_flag) {
-    if (verbose_flag)
-      printf("Checking exact...\n");
-    exact_flag = 1;
-    stl_check_facets_exact(stl);
-    stl->stats.facets_w_1_bad_edge =
-      (stl->stats.connected_facets_2_edge -
-       stl->stats.connected_facets_3_edge);
-    stl->stats.facets_w_2_bad_edge =
-      (stl->stats.connected_facets_1_edge -
-       stl->stats.connected_facets_2_edge);
-    stl->stats.facets_w_3_bad_edge =
-      (stl->stats.number_of_facets -
-       stl->stats.connected_facets_1_edge);
-  }
-
-  if(nearby_flag || fixall_flag) {
-    if(!tolerance_flag) {
-      tolerance = stl->stats.shortest_edge;
-    }
-    if(!increment_flag) {
-      increment = stl->stats.bounding_diameter / 10000.0;
-    }
-
-    if(stl->stats.connected_facets_3_edge < stl->stats.number_of_facets) {
-      for(i = 0; i < iterations; i++) {
-        if(stl->stats.connected_facets_3_edge <
-            stl->stats.number_of_facets) {
-          if (verbose_flag)
-            printf("\
-Checking nearby. Tolerance= %f Iteration=%d of %d...",
-                 tolerance, i + 1, iterations);
-          stl_check_facets_nearby(stl, tolerance);
-          if (verbose_flag)
-            printf("  Fixed %d edges.\n",
-                 stl->stats.edges_fixed - last_edges_fixed);
-          last_edges_fixed = stl->stats.edges_fixed;
-          tolerance += increment;
-        } else {
-          if (verbose_flag)
-            printf("\
-All facets connected.  No further nearby check necessary.\n");
-          break;
-        }
-      }
-    } else {
-      if (verbose_flag)
-        printf("All facets connected.  No nearby check necessary.\n");
-    }
-  }
-
-  if(remove_unconnected_flag || fixall_flag || fill_holes_flag) {
-    if(stl->stats.connected_facets_3_edge <  stl->stats.number_of_facets) {
-      if (verbose_flag)
-        printf("Removing unconnected facets...\n");
-      stl_remove_unconnected_facets(stl);
-    } else
-      if (verbose_flag)
-        printf("No unconnected need to be removed.\n");
-  }
-
-  if(fill_holes_flag || fixall_flag) {
-    if(stl->stats.connected_facets_3_edge <  stl->stats.number_of_facets) {
-      if (verbose_flag)
-        printf("Filling holes...\n");
-      stl_fill_holes(stl);
-    } else
-      if (verbose_flag)
-        printf("No holes need to be filled.\n");
-  }
-
-  if(reverse_all_flag) {
-    if (verbose_flag)
-      printf("Reversing all facets...\n");
-    stl_reverse_all_facets(stl);
-  }
-
-  if(normal_directions_flag || fixall_flag) {
-    if (verbose_flag)
-      printf("Checking normal directions...\n");
-    stl_fix_normal_directions(stl);
-  }
-
-  if(normal_values_flag || fixall_flag) {
-    if (verbose_flag)
-      printf("Checking normal values...\n");
-    stl_fix_normal_values(stl);
-  }
-
-  /* Always calculate the volume.  It shouldn't take too long */
-  if (verbose_flag)
-    printf("Calculating volume...\n");
-  stl_calculate_volume(stl);
-
-  if(exact_flag) {
-    if (verbose_flag)
-      printf("Verifying neighbors...\n");
-    stl_verify_neighbors(stl);
-  }
+static float get_volume(stl_file *stl)
+{
+  	// Choose a point, any point as the reference.
+  	stl_vertex p0 = stl->facet_start[0].vertex[0];
+  	float volume = 0.f;
+  	for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+    	// Do dot product to get distance from point to plane.
+    	float height = stl->facet_start[i].normal.dot(stl->facet_start[i].vertex[0] - p0);
+    	float area   = get_area(&stl->facet_start[i]);
+    	volume += (area * height) / 3.0f;
+  	}
+  	return volume;
+}
+
+void stl_calculate_volume(stl_file *stl)
+{
+  	stl->stats.volume = get_volume(stl);
+  	if (stl->stats.volume < 0.0) {
+    	stl_reverse_all_facets(stl);
+    	stl->stats.volume = -stl->stats.volume;
+  	}
+}
+
+void stl_repair(
+	stl_file *stl,
+	bool fixall_flag,
+	bool exact_flag,
+	bool tolerance_flag,
+	float tolerance,
+	bool increment_flag,
+	float increment,
+	bool nearby_flag,
+	int iterations,
+	bool remove_unconnected_flag,
+	bool fill_holes_flag,
+	bool normal_directions_flag,
+	bool normal_values_flag,
+	bool reverse_all_flag,
+	bool verbose_flag)
+{
+	if (exact_flag || fixall_flag || nearby_flag || remove_unconnected_flag || fill_holes_flag || normal_directions_flag) {
+		if (verbose_flag)
+		  	printf("Checking exact...\n");
+		exact_flag = true;
+		stl_check_facets_exact(stl);
+		stl->stats.facets_w_1_bad_edge = (stl->stats.connected_facets_2_edge - stl->stats.connected_facets_3_edge);
+		stl->stats.facets_w_2_bad_edge = (stl->stats.connected_facets_1_edge - stl->stats.connected_facets_2_edge);
+		stl->stats.facets_w_3_bad_edge = (stl->stats.number_of_facets - stl->stats.connected_facets_1_edge);
+	}
+
+  	if (nearby_flag || fixall_flag) {
+    	if (! tolerance_flag)
+      		tolerance = stl->stats.shortest_edge;
+ 	   	if (! increment_flag)
+      		increment = stl->stats.bounding_diameter / 10000.0;
+    }
+
+	if (stl->stats.connected_facets_3_edge < stl->stats.number_of_facets) {
+	  	int last_edges_fixed = 0;
+	  	for (int i = 0; i < iterations; ++ i) {
+	    	if (stl->stats.connected_facets_3_edge < stl->stats.number_of_facets) {
+	      		if (verbose_flag)
+	        		printf("Checking nearby. Tolerance= %f Iteration=%d of %d...", tolerance, i + 1, iterations);
+	      		stl_check_facets_nearby(stl, tolerance);
+	      		if (verbose_flag)
+	        		printf("  Fixed %d edges.\n", stl->stats.edges_fixed - last_edges_fixed);
+	      		last_edges_fixed = stl->stats.edges_fixed;
+	      		tolerance += increment;
+	    	} else {
+	    		if (verbose_flag)
+	        		printf("All facets connected.  No further nearby check necessary.\n");
+		      	break;
+		    }
+	  	}
+	} else if (verbose_flag)
+	    printf("All facets connected.  No nearby check necessary.\n");
+
+	if (remove_unconnected_flag || fixall_flag || fill_holes_flag) {
+		if (stl->stats.connected_facets_3_edge <  stl->stats.number_of_facets) {
+	  		if (verbose_flag)
+	    		printf("Removing unconnected facets...\n");
+	  		stl_remove_unconnected_facets(stl);
+		} else if (verbose_flag)
+	    	printf("No unconnected need to be removed.\n");
+	}
+
+	if (fill_holes_flag || fixall_flag) {
+		if (stl->stats.connected_facets_3_edge <  stl->stats.number_of_facets) {
+	  		if (verbose_flag)
+	    		printf("Filling holes...\n");
+	  		stl_fill_holes(stl);
+		} else if (verbose_flag)
+	    	printf("No holes need to be filled.\n");
+	}
+
+	if (reverse_all_flag) {
+		if (verbose_flag)
+	  		printf("Reversing all facets...\n");
+		stl_reverse_all_facets(stl);
+	}
+
+	if (normal_directions_flag || fixall_flag) {
+		if (verbose_flag)
+	  		printf("Checking normal directions...\n");
+		stl_fix_normal_directions(stl);
+	}
+
+	if (normal_values_flag || fixall_flag) {
+		if (verbose_flag)
+	  		printf("Checking normal values...\n");
+		stl_fix_normal_values(stl);
+	}
+
+  	// Always calculate the volume.  It shouldn't take too long.
+	if (verbose_flag)
+		printf("Calculating volume...\n");
+	stl_calculate_volume(stl);
+
+	if (exact_flag) {
+		if (verbose_flag)
+	  		printf("Verifying neighbors...\n");
+		stl_verify_neighbors(stl);
+	}
 }
diff --git a/src/libnest2d/CMakeLists.txt b/src/libnest2d/CMakeLists.txt
index 2508c984a..587b814b2 100644
--- a/src/libnest2d/CMakeLists.txt
+++ b/src/libnest2d/CMakeLists.txt
@@ -48,6 +48,9 @@ set(LIBNEST2D_SRCFILES
     ${SRC_DIR}/libnest2d/optimizer.hpp
     ${SRC_DIR}/libnest2d/utils/metaloop.hpp
     ${SRC_DIR}/libnest2d/utils/rotfinder.hpp
+    ${SRC_DIR}/libnest2d/utils/rotcalipers.hpp
+    ${SRC_DIR}/libnest2d/utils/bigint.hpp
+    ${SRC_DIR}/libnest2d/utils/rational.hpp
     ${SRC_DIR}/libnest2d/placers/placer_boilerplate.hpp
     ${SRC_DIR}/libnest2d/placers/bottomleftplacer.hpp
     ${SRC_DIR}/libnest2d/placers/nfpplacer.hpp
@@ -70,12 +73,13 @@ if(TBB_FOUND)
     # The Intel TBB library will use the std::exception_ptr feature of C++11.
     target_compile_definitions(libnest2d INTERFACE -DTBB_USE_CAPTURED_EXCEPTION=0)
 
-    target_link_libraries(libnest2d INTERFACE tbb)
-    # The following breaks compilation on Visual Studio in Debug mode.
-    #find_package(Threads REQUIRED)
-    #target_link_libraries(libnest2d INTERFACE ${TBB_LIBRARIES} ${CMAKE_DL_LIBS}
-    #    Threads::Threads
-    #    )
+    find_package(Threads REQUIRED)
+    target_link_libraries(libnest2d INTERFACE 
+        tbb # VS debug mode needs linking this way:
+        # ${TBB_LIBRARIES} 
+        ${CMAKE_DL_LIBS}
+        Threads::Threads
+        )
 else()
    find_package(OpenMP QUIET)
 
@@ -92,10 +96,11 @@ endif()
 
 add_subdirectory(${SRC_DIR}/libnest2d/backends/${LIBNEST2D_GEOMETRIES})
 target_link_libraries(libnest2d INTERFACE ${LIBNEST2D_GEOMETRIES}Backend)
+
 add_subdirectory(${SRC_DIR}/libnest2d/optimizers/${LIBNEST2D_OPTIMIZER})
 target_link_libraries(libnest2d INTERFACE ${LIBNEST2D_OPTIMIZER}Optimizer)
 
-#target_sources(libnest2d INTERFACE ${LIBNEST2D_SRCFILES})
+# target_sources(libnest2d INTERFACE ${LIBNEST2D_SRCFILES})
 target_include_directories(libnest2d INTERFACE ${SRC_DIR})
 
 if(NOT LIBNEST2D_HEADER_ONLY)
diff --git a/src/libnest2d/include/libnest2d.h b/src/libnest2d/include/libnest2d.h
index 4ad752421..a6eb36a4b 100644
--- a/src/libnest2d/include/libnest2d.h
+++ b/src/libnest2d/include/libnest2d.h
@@ -47,6 +47,17 @@ using NfpPlacer = _NfpPlacer<Box>;
 // This supports only box shaped bins
 using BottomLeftPlacer = placers::_BottomLeftPlacer<PolygonImpl>;
 
+#ifdef LIBNEST2D_STATIC
+
+extern template class Nester<NfpPlacer, FirstFitSelection>;
+extern template class Nester<BottomLeftPlacer, FirstFitSelection>;
+extern template PackGroup Nester<NfpPlacer, FirstFitSelection>::execute(
+        std::vector<Item>::iterator, std::vector<Item>::iterator);
+extern template PackGroup Nester<BottomLeftPlacer, FirstFitSelection>::execute(
+        std::vector<Item>::iterator, std::vector<Item>::iterator);
+
+#endif
+
 template<class Placer = NfpPlacer,
          class Selector = FirstFitSelection,
          class Iterator = std::vector<Item>::iterator>
@@ -60,19 +71,6 @@ PackGroup nest(Iterator from, Iterator to,
     return nester.execute(from, to);
 }
 
-template<class Placer = NfpPlacer,
-         class Selector = FirstFitSelection,
-         class Container = std::vector<Item>>
-PackGroup nest(Container&& cont,
-               const typename Placer::BinType& bin,
-               Coord dist = 0,
-               const typename Placer::Config& pconf = {},
-               const typename Selector::Config& sconf = {})
-{
-    return nest<Placer, Selector>(cont.begin(), cont.end(),
-                                  bin, dist, pconf, sconf);
-}
-
 template<class Placer = NfpPlacer,
          class Selector = FirstFitSelection,
          class Iterator = std::vector<Item>::iterator>
@@ -90,6 +88,42 @@ PackGroup nest(Iterator from, Iterator to,
     return nester.execute(from, to);
 }
 
+#ifdef LIBNEST2D_STATIC
+
+extern template class Nester<NfpPlacer, FirstFitSelection>;
+extern template class Nester<BottomLeftPlacer, FirstFitSelection>;
+
+extern template PackGroup nest(std::vector<Item>::iterator from, 
+                               std::vector<Item>::iterator to,
+                               const Box& bin,
+                               Coord dist = 0,
+                               const NfpPlacer::Config& pconf,
+                               const FirstFitSelection::Config& sconf);
+
+extern template PackGroup nest(std::vector<Item>::iterator from, 
+                               std::vector<Item>::iterator to,
+                               const Box& bin,
+                               ProgressFunction prg,
+                               StopCondition scond,
+                               Coord dist = 0,
+                               const NfpPlacer::Config& pconf,
+                               const FirstFitSelection::Config& sconf);
+
+#endif
+
+template<class Placer = NfpPlacer,
+         class Selector = FirstFitSelection,
+         class Container = std::vector<Item>>
+PackGroup nest(Container&& cont,
+               const typename Placer::BinType& bin,
+               Coord dist = 0,
+               const typename Placer::Config& pconf = {},
+               const typename Selector::Config& sconf = {})
+{
+    return nest<Placer, Selector>(cont.begin(), cont.end(),
+                                  bin, dist, pconf, sconf);
+}
+
 template<class Placer = NfpPlacer,
          class Selector = FirstFitSelection,
          class Container = std::vector<Item>>
@@ -105,71 +139,6 @@ PackGroup nest(Container&& cont,
                                   bin, prg, scond, dist, pconf, sconf);
 }
 
-#ifdef LIBNEST2D_STATIC
-extern template
-PackGroup nest<NfpPlacer, FirstFitSelection, std::vector<Item>&>(
-    std::vector<Item>& cont,
-    const Box& bin,
-    Coord dist,
-    const NfpPlacer::Config& pcfg,
-    const FirstFitSelection::Config& scfg
-);
-
-extern template
-PackGroup nest<NfpPlacer, FirstFitSelection, std::vector<Item>&>(
-    std::vector<Item>& cont,
-    const Box& bin,
-    ProgressFunction prg,
-    StopCondition scond,
-    Coord dist,
-    const NfpPlacer::Config& pcfg,
-    const FirstFitSelection::Config& scfg
-);
-
-extern template
-PackGroup nest<NfpPlacer, FirstFitSelection, std::vector<Item>>(
-    std::vector<Item>&& cont,
-    const Box& bin,
-    Coord dist,
-    const NfpPlacer::Config& pcfg,
-    const FirstFitSelection::Config& scfg
-);
-
-extern template
-PackGroup nest<NfpPlacer, FirstFitSelection, std::vector<Item>>(
-    std::vector<Item>&& cont,
-    const Box& bin,
-    ProgressFunction prg,
-    StopCondition scond,
-    Coord dist,
-    const NfpPlacer::Config& pcfg,
-    const FirstFitSelection::Config& scfg
-);
-
-extern template
-PackGroup nest<NfpPlacer, FirstFitSelection, std::vector<Item>::iterator>(
-    std::vector<Item>::iterator from,
-    std::vector<Item>::iterator to,
-    const Box& bin,
-    Coord dist,
-    const NfpPlacer::Config& pcfg,
-    const FirstFitSelection::Config& scfg
-);
-
-extern template
-PackGroup nest<NfpPlacer, FirstFitSelection, std::vector<Item>::iterator>(
-    std::vector<Item>::iterator from,
-    std::vector<Item>::iterator to,
-    const Box& bin,
-    ProgressFunction prg,
-    StopCondition scond,
-    Coord dist,
-    const NfpPlacer::Config& pcfg,
-    const FirstFitSelection::Config& scfg
-);
-
-#endif
-
 }
 
 #endif // LIBNEST2D_H
diff --git a/src/libnest2d/include/libnest2d/backends/clipper/CMakeLists.txt b/src/libnest2d/include/libnest2d/backends/clipper/CMakeLists.txt
index cf8a37350..202089356 100644
--- a/src/libnest2d/include/libnest2d/backends/clipper/CMakeLists.txt
+++ b/src/libnest2d/include/libnest2d/backends/clipper/CMakeLists.txt
@@ -33,19 +33,18 @@ if(NOT TARGET clipper) # If there is a clipper target in the parent project we a
             #                  ${clipper_library_BINARY_DIR}
             # )
 
-            add_library(ClipperBackend STATIC
+            add_library(clipperBackend STATIC
                 ${clipper_library_SOURCE_DIR}/clipper.cpp
                 ${clipper_library_SOURCE_DIR}/clipper.hpp)
 
-            target_include_directories(ClipperBackend INTERFACE 
-                ${clipper_library_SOURCE_DIR})
+            target_include_directories(clipperBackend INTERFACE ${clipper_library_SOURCE_DIR})
         else()
             message(FATAL_ERROR "Can't find clipper library and no SVN client found to download.
                 You can download the clipper sources and define a clipper target in your project, that will work for libnest2d.")
         endif()
     else()
-        add_library(ClipperBackend INTERFACE)
-        target_link_libraries(ClipperBackend INTERFACE Clipper::Clipper)
+        add_library(clipperBackend INTERFACE)
+        target_link_libraries(clipperBackend INTERFACE Clipper::Clipper)
     endif()
 else()
     # set(CLIPPER_INCLUDE_DIRS "" PARENT_SCOPE)
@@ -69,6 +68,6 @@ target_link_libraries(clipperBackend INTERFACE Boost::boost )
 
 target_compile_definitions(clipperBackend INTERFACE LIBNEST2D_BACKEND_CLIPPER)
 
-# And finally plug the ClipperBackend into libnest2d
-#target_link_libraries(libnest2d INTERFACE ClipperBackend)
+# And finally plug the clipperBackend into libnest2d
+# target_link_libraries(libnest2d INTERFACE clipperBackend)
 
diff --git a/src/libnest2d/include/libnest2d/backends/clipper/clipper_polygon.hpp b/src/libnest2d/include/libnest2d/backends/clipper/clipper_polygon.hpp
index e9fbfbd18..6511fbb72 100644
--- a/src/libnest2d/include/libnest2d/backends/clipper/clipper_polygon.hpp
+++ b/src/libnest2d/include/libnest2d/backends/clipper/clipper_polygon.hpp
@@ -12,13 +12,13 @@ struct Polygon {
     inline Polygon() = default;
 
     inline explicit Polygon(const Path& cont): Contour(cont) {}
-    inline explicit Polygon(const Paths& holes):
-        Holes(holes) {}
+//    inline explicit Polygon(const Paths& holes):
+//        Holes(holes) {}
     inline Polygon(const Path& cont, const Paths& holes):
         Contour(cont), Holes(holes) {}
 
     inline explicit Polygon(Path&& cont): Contour(std::move(cont)) {}
-    inline explicit Polygon(Paths&& holes): Holes(std::move(holes)) {}
+//    inline explicit Polygon(Paths&& holes): Holes(std::move(holes)) {}
     inline Polygon(Path&& cont, Paths&& holes):
         Contour(std::move(cont)), Holes(std::move(holes)) {}
 };
@@ -42,7 +42,7 @@ inline IntPoint& operator -=(IntPoint& p, const IntPoint& pa ) {
     return p;
 }
 
-inline IntPoint operator -(IntPoint& p ) {
+inline IntPoint operator -(const IntPoint& p ) {
     IntPoint ret = p;
     ret.X = -ret.X;
     ret.Y = -ret.Y;
diff --git a/src/libnest2d/include/libnest2d/backends/clipper/geometries.hpp b/src/libnest2d/include/libnest2d/backends/clipper/geometries.hpp
index 232668f61..e9fad405b 100644
--- a/src/libnest2d/include/libnest2d/backends/clipper/geometries.hpp
+++ b/src/libnest2d/include/libnest2d/backends/clipper/geometries.hpp
@@ -20,43 +20,23 @@ using PathImpl  = ClipperLib::Path;
 using HoleStore = ClipperLib::Paths;
 using PolygonImpl = ClipperLib::Polygon;
 
-// Type of coordinate units used by Clipper
-template<> struct CoordType<PointImpl> {
-    using Type = ClipperLib::cInt;
-};
-
-// Type of point used by Clipper
-template<> struct PointType<PolygonImpl> {
-    using Type = PointImpl;
-};
-
-template<> struct PointType<PathImpl> {
-    using Type = PointImpl;
-};
-
-template<> struct PointType<PointImpl> {
-    using Type = PointImpl;
-};
-
-template<> struct CountourType<PolygonImpl> {
-    using Type = PathImpl;
-};
-
 template<> struct ShapeTag<PolygonImpl> { using Type = PolygonTag; };
-template<> struct ShapeTag<PathImpl> { using Type = PathTag; };
-template<> struct ShapeTag<PointImpl> { using Type = PointTag; };
+template<> struct ShapeTag<PathImpl>    { using Type = PathTag; };
+template<> struct ShapeTag<PointImpl>   { using Type = PointTag; };
 
-template<> struct ShapeTag<TMultiShape<PolygonImpl>> {
-    using Type = MultiPolygonTag;
-};
+// Type of coordinate units used by Clipper. Enough to specialize for point,
+// the rest of the types will work (Path, Polygon)
+template<> struct CoordType<PointImpl> { using Type = ClipperLib::cInt; };
 
-template<> struct PointType<TMultiShape<PolygonImpl>> {
-    using Type = PointImpl;
-};
+// Enough to specialize for path, it will work for multishape and Polygon
+template<> struct PointType<PathImpl> { using Type = PointImpl; };
 
-template<> struct HolesContainer<PolygonImpl> {
-    using Type = ClipperLib::Paths;
-};
+// This is crucial. CountourType refers to itself by default, so we don't have
+// to secialize for clipper Path. ContourType<PathImpl>::Type is PathImpl.
+template<> struct ContourType<PolygonImpl> { using Type = PathImpl; };
+
+// The holes are contained in Clipper::Paths
+template<> struct HolesContainer<PolygonImpl> { using Type = ClipperLib::Paths; };
 
 namespace pointlike {
 
@@ -86,39 +66,11 @@ template<> inline TCoord<PointImpl>& y(PointImpl& p)
 
 }
 
+// Using the libnest2d default area implementation
 #define DISABLE_BOOST_AREA
 
-namespace _smartarea {
-
-template<Orientation o>
-inline double area(const PolygonImpl& /*sh*/) {
-    return std::nan("");
-}
-
-template<>
-inline double area<Orientation::COUNTER_CLOCKWISE>(const PolygonImpl& sh) {
-    return std::accumulate(sh.Holes.begin(), sh.Holes.end(),
-                           ClipperLib::Area(sh.Contour),
-                           [](double a, const ClipperLib::Path& pt){
-        return a + ClipperLib::Area(pt);
-    });
-}
-
-template<>
-inline double area<Orientation::CLOCKWISE>(const PolygonImpl& sh) {
-    return -area<Orientation::COUNTER_CLOCKWISE>(sh);
-}
-
-}
-
 namespace shapelike {
 
-// Tell libnest2d how to make string out of a ClipperPolygon object
-template<> inline double area(const PolygonImpl& sh, const PolygonTag&)
-{
-    return _smartarea::area<OrientationType<PolygonImpl>::Value>(sh);
-}
-
 template<> inline void offset(PolygonImpl& sh, TCoord<PointImpl> distance)
 {
     #define DISABLE_BOOST_OFFSET
@@ -200,43 +152,16 @@ inline PolygonImpl create(const PathImpl& path, const HoleStore& holes)
 {
     PolygonImpl p;
     p.Contour = path;
-
-    // Expecting that the coordinate system Y axis is positive in upwards
-    // direction
-    if(ClipperLib::Orientation(p.Contour)) {
-        // Not clockwise then reverse the b*tch
-        ClipperLib::ReversePath(p.Contour);
-    }
-
     p.Holes = holes;
-    for(auto& h : p.Holes) {
-        if(!ClipperLib::Orientation(h)) {
-            ClipperLib::ReversePath(h);
-        }
-    }
-
+   
     return p;
 }
 
 template<> inline PolygonImpl create( PathImpl&& path, HoleStore&& holes) {
     PolygonImpl p;
     p.Contour.swap(path);
-
-    // Expecting that the coordinate system Y axis is positive in upwards
-    // direction
-    if(ClipperLib::Orientation(p.Contour)) {
-        // Not clockwise then reverse the b*tch
-        ClipperLib::ReversePath(p.Contour);
-    }
-
     p.Holes.swap(holes);
-
-    for(auto& h : p.Holes) {
-        if(!ClipperLib::Orientation(h)) {
-            ClipperLib::ReversePath(h);
-        }
-    }
-
+    
     return p;
 }
 
@@ -314,13 +239,13 @@ inline void rotate(PolygonImpl& sh, const Radians& rads)
 } // namespace shapelike
 
 #define DISABLE_BOOST_NFP_MERGE
-inline std::vector<PolygonImpl> clipper_execute(
+inline TMultiShape<PolygonImpl> clipper_execute(
         ClipperLib::Clipper& clipper,
         ClipperLib::ClipType clipType,
         ClipperLib::PolyFillType subjFillType = ClipperLib::pftEvenOdd,
         ClipperLib::PolyFillType clipFillType = ClipperLib::pftEvenOdd)
 {
-    shapelike::Shapes<PolygonImpl> retv;
+    TMultiShape<PolygonImpl> retv;
 
     ClipperLib::PolyTree result;
     clipper.Execute(clipType, result, subjFillType, clipFillType);
@@ -370,8 +295,8 @@ inline std::vector<PolygonImpl> clipper_execute(
 
 namespace nfp {
 
-template<> inline std::vector<PolygonImpl>
-merge(const std::vector<PolygonImpl>& shapes)
+template<> inline TMultiShape<PolygonImpl>
+merge(const TMultiShape<PolygonImpl>& shapes)
 {
     ClipperLib::Clipper clipper(ClipperLib::ioReverseSolution);
 
@@ -394,6 +319,8 @@ merge(const std::vector<PolygonImpl>& shapes)
 
 }
 
+#define DISABLE_BOOST_CONVEX_HULL
+
 //#define DISABLE_BOOST_SERIALIZE
 //#define DISABLE_BOOST_UNSERIALIZE
 
diff --git a/src/libnest2d/include/libnest2d/common.hpp b/src/libnest2d/include/libnest2d/common.hpp
index 6867f76f3..66e095ae2 100644
--- a/src/libnest2d/include/libnest2d/common.hpp
+++ b/src/libnest2d/include/libnest2d/common.hpp
@@ -9,6 +9,7 @@
 #include <string>
 #include <cmath>
 #include <type_traits>
+#include <limits>
 
 #if defined(_MSC_VER) &&  _MSC_VER <= 1800 || __cplusplus < 201103L
     #define BP2D_NOEXCEPT
@@ -197,6 +198,33 @@ public:
     }
 };
 
+struct ScalarTag {};
+struct BigIntTag {};
+struct RationalTag {};
+
+template<class T> struct _NumTag { 
+    using Type = 
+        enable_if_t<std::is_arithmetic<T>::value, ScalarTag>; 
+};
+
+template<class T> using NumTag = typename _NumTag<remove_cvref_t<T>>::Type;
+
+/// A local version for abs that is garanteed to work with libnest2d types
+template <class T> inline T abs(const T& v, ScalarTag) 
+{ 
+    return std::abs(v); 
+}
+
+template<class T> inline T abs(const T& v) { return abs(v, NumTag<T>()); }
+
+template<class T2, class T1> inline T2 cast(const T1& v, ScalarTag, ScalarTag) 
+{
+    return static_cast<T2>(v);    
+}
+
+template<class T2, class T1> inline T2 cast(const T1& v) { 
+    return cast<T2, T1>(v, NumTag<T1>(), NumTag<T2>());
+}
 
 }
 #endif // LIBNEST2D_CONFIG_HPP
diff --git a/src/libnest2d/include/libnest2d/geometry_traits.hpp b/src/libnest2d/include/libnest2d/geometry_traits.hpp
index 917f5280d..6c55d0e3f 100644
--- a/src/libnest2d/include/libnest2d/geometry_traits.hpp
+++ b/src/libnest2d/include/libnest2d/geometry_traits.hpp
@@ -7,45 +7,125 @@
 #include <array>
 #include <vector>
 #include <numeric>
-#include <limits>
 #include <iterator>
 #include <cmath>
+#include <cstdint>
 
-#include "common.hpp"
+#include <libnest2d/common.hpp>
 
 namespace libnest2d {
 
+// Meta tags for different geometry concepts. 
+struct PointTag {};
+struct PolygonTag {};
+struct PathTag {};
+struct MultiPolygonTag {};
+struct BoxTag {};
+struct CircleTag {};
+
+/// Meta-function to derive the tag of a shape type.
+template<class Shape> struct ShapeTag { using Type = typename Shape::Tag; };
+
+/// Tag<S> will be used instead of `typename ShapeTag<S>::Type`
+template<class S> using Tag = typename ShapeTag<remove_cvref_t<S>>::Type;
+
+/// Meta function to derive the contour type for a polygon which could be itself
+template<class RawShape> struct ContourType { using Type = RawShape; };
+
+/// TContour<RawShape> instead of `typename ContourType<RawShape>::type`
+template<class RawShape>
+using TContour = typename ContourType<remove_cvref_t<RawShape>>::Type;
+
+/// Getting the type of point structure used by a shape.
+template<class Sh> struct PointType { 
+    using Type = typename PointType<TContour<Sh>>::Type; 
+};
+
+/// TPoint<ShapeClass> as shorthand for `typename PointType<ShapeClass>::Type`.
+template<class Shape>
+using TPoint = typename PointType<remove_cvref_t<Shape>>::Type;
+
 /// Getting the coordinate data type for a geometry class.
-template<class GeomClass> struct CoordType { using Type = long; };
+template<class GeomClass> struct CoordType { 
+    using Type = typename CoordType<TPoint<GeomClass>>::Type; 
+};
 
 /// TCoord<GeomType> as shorthand for typename `CoordType<GeomType>::Type`.
 template<class GeomType>
 using TCoord = typename CoordType<remove_cvref_t<GeomType>>::Type;
 
 
-/// Getting the type of point structure used by a shape.
-template<class Sh> struct PointType { using Type = typename Sh::PointType; };
+/// Getting the computation type for a certain geometry type.
+/// It is the coordinate type by default but it is advised that a type with
+/// larger precision and (or) range is specified.
+template<class T, bool = std::is_arithmetic<T>::value> struct ComputeType {};
 
-/// TPoint<ShapeClass> as shorthand for `typename PointType<ShapeClass>::Type`.
-template<class Shape>
-using TPoint = typename PointType<remove_cvref_t<Shape>>::Type;
+/// A compute type is introduced to hold the results of computations on
+/// coordinates and points. It should be larger in range than the coordinate 
+/// type or the range of coordinates should be limited to not loose precision.
+template<class GeomClass> struct ComputeType<GeomClass, false> {
+    using Type = typename ComputeType<TCoord<GeomClass>>::Type;
+};
 
+/// libnest2d will choose a default compute type for various coordinate types
+/// if the backend has not specified anything.
+template<class T> struct DoublePrecision { using Type = T; };
+template<> struct DoublePrecision<int8_t> { using Type = int16_t; };
+template<> struct DoublePrecision<int16_t> { using Type = int32_t; };
+template<> struct DoublePrecision<int32_t> { using Type = int64_t; };
+template<> struct DoublePrecision<float> { using Type = double; };
+template<> struct DoublePrecision<double> { using Type = long double; };
+template<class I> struct ComputeType<I, true> {
+    using Type = typename DoublePrecision<I>::Type;
+};
 
-template<class RawShape> struct CountourType { using Type = RawShape; };
-
-template<class RawShape>
-using TContour = typename CountourType<remove_cvref_t<RawShape>>::Type;
-
+/// TCompute<T> shorthand for `typename ComputeType<T>::Type`
+template<class T> using TCompute = typename ComputeType<remove_cvref_t<T>>::Type;
 
+/// A meta function to derive a container type for holes in a polygon
 template<class RawShape>
 struct HolesContainer { using Type = std::vector<TContour<RawShape>>;  };
 
+/// Shorthand for `typename HolesContainer<RawShape>::Type`
 template<class RawShape>
 using THolesContainer = typename HolesContainer<remove_cvref_t<RawShape>>::Type;
 
+/*
+ * TContour, TPoint, TCoord and TCompute should be usable for any type for which
+ * it makes sense. For example, the point type could be derived from the contour,
+ * the polygon and (or) the multishape as well. The coordinate type also and
+ * including the point type. TCoord<Polygon>, TCoord<Path>, TCoord<Point> are
+ * all valid types and derives the coordinate type of template argument Polygon,
+ * Path and Point. This is also true for TCompute, but it can also take the 
+ * coordinate type as argument.
+ */
 
-template<class RawShape>
-struct LastPointIsFirst { static const bool Value = true; };
+/*
+ * A Multi shape concept is also introduced. A multi shape is something that
+ * can contain the result of an operation where the input is one polygon and 
+ * the result could be many polygons or path -> paths. The MultiShape should be
+ * a container type. If the backend does not specialize the MultiShape template,
+ * a default multi shape container will be used.
+ */
+
+/// The default multi shape container.
+template<class S> struct DefaultMultiShape: public std::vector<S> {
+    using Tag = MultiPolygonTag;
+    template<class...Args> DefaultMultiShape(Args&&...args):
+        std::vector<S>(std::forward<Args>(args)...) {}
+};
+
+/// The MultiShape Type trait which gets the container type for a geometry type.
+template<class S> struct MultiShape { using Type = DefaultMultiShape<S>; };
+
+/// use TMultiShape<S> instead of `typename MultiShape<S>::Type`
+template<class S> 
+using TMultiShape = typename MultiShape<remove_cvref_t<S>>::Type;
+
+// A specialization of ContourType to work with the default multishape type
+template<class S> struct ContourType<DefaultMultiShape<S>> {
+    using Type = typename ContourType<S>::Type;
+};
 
 enum class Orientation {
     CLOCKWISE,
@@ -59,6 +139,11 @@ struct OrientationType {
     static const Orientation Value = Orientation::CLOCKWISE;
 };
 
+template<class T> inline /*constexpr*/ bool is_clockwise() { 
+    return OrientationType<TContour<T>>::Value == Orientation::CLOCKWISE; 
+}
+
+
 /**
  * \brief A point pair base class for other point pairs (segment, box, ...).
  * \tparam RawPoint The actual point type to use.
@@ -69,21 +154,6 @@ struct PointPair {
     RawPoint p2;
 };
 
-struct PointTag {};
-struct PolygonTag {};
-struct PathTag {};
-struct MultiPolygonTag {};
-struct BoxTag {};
-struct CircleTag {};
-
-/// Meta-functions to derive the tags
-template<class Shape> struct ShapeTag { using Type = typename Shape::Tag; };
-template<class S> using Tag = typename ShapeTag<remove_cvref_t<S>>::Type;
-
-template<class S> struct MultiShape { using Type = std::vector<S>; };
-template<class S>
-using TMultiShape =typename MultiShape<remove_cvref_t<S>>::Type;
-
 /**
  * \brief An abstraction of a box;
  */
@@ -114,11 +184,16 @@ public:
 
     inline RawPoint center() const BP2D_NOEXCEPT;
 
-    inline double area() const BP2D_NOEXCEPT {
-        return double(width()*height());
+    template<class Unit = TCompute<RawPoint>> 
+    inline Unit area() const BP2D_NOEXCEPT {
+        return Unit(width())*height();
     }
 };
 
+template<class S> struct PointType<_Box<S>> { 
+    using Type = typename _Box<S>::PointType; 
+};
+
 template<class RawPoint>
 class _Circle {
     RawPoint center_;
@@ -129,7 +204,6 @@ public:
     using PointType = RawPoint;
 
     _Circle() = default;
-
     _Circle(const RawPoint& center, double r): center_(center), radius_(r) {}
 
     inline const RawPoint& center() const BP2D_NOEXCEPT { return center_; }
@@ -137,12 +211,16 @@ public:
 
     inline double radius() const BP2D_NOEXCEPT { return radius_; }
     inline void radius(double r) { radius_ = r; }
-
+    
     inline double area() const BP2D_NOEXCEPT {
-        return 2.0*Pi*radius_*radius_;
+        return Pi_2 * radius_ * radius_;
     }
 };
 
+template<class S> struct PointType<_Circle<S>> {
+    using Type = typename _Circle<S>::PointType;
+};
+
 /**
  * \brief An abstraction of a directed line segment with two points.
  */
@@ -185,7 +263,12 @@ public:
     inline Radians angleToXaxis() const;
 
     /// The length of the segment in the measure of the coordinate system.
-    inline double length();
+    template<class Unit = TCompute<RawPoint>> inline Unit sqlength() const;
+    
+};
+
+template<class S> struct PointType<_Segment<S>> { 
+    using Type = typename _Circle<S>::PointType; 
 };
 
 // This struct serves almost as a namespace. The only difference is that is can
@@ -216,33 +299,56 @@ inline TCoord<RawPoint>& y(RawPoint& p)
     return p.y();
 }
 
-template<class RawPoint>
-inline double distance(const RawPoint& /*p1*/, const RawPoint& /*p2*/)
+template<class RawPoint, class Unit = TCompute<RawPoint>>
+inline Unit squaredDistance(const RawPoint& p1, const RawPoint& p2)
 {
-    static_assert(always_false<RawPoint>::value,
-                  "PointLike::distance(point, point) unimplemented!");
-    return 0;
+    auto x1 = Unit(x(p1)), y1 = Unit(y(p1)), x2 = Unit(x(p2)), y2 = Unit(y(p2));
+    Unit a = (x2 - x1), b = (y2 - y1);
+    return a * a + b * b;
 }
 
 template<class RawPoint>
-inline double distance(const RawPoint& /*p1*/,
-                       const _Segment<RawPoint>& /*s*/)
+inline double distance(const RawPoint& p1, const RawPoint& p2)
 {
-    static_assert(always_false<RawPoint>::value,
-                  "PointLike::distance(point, segment) unimplemented!");
-    return 0;
+    return std::sqrt(squaredDistance<RawPoint, double>(p1, p2));
 }
 
-template<class RawPoint>
-inline std::pair<TCoord<RawPoint>, bool> horizontalDistance(
+// create perpendicular vector
+template<class Pt> inline Pt perp(const Pt& p) 
+{ 
+    return Pt(y(p), -x(p));
+}
+
+template<class Pt, class Unit = TCompute<Pt>> 
+inline Unit dotperp(const Pt& a, const Pt& b) 
+{ 
+    return Unit(x(a)) * Unit(y(b)) - Unit(y(a)) * Unit(x(b)); 
+}
+
+// dot product
+template<class Pt, class Unit = TCompute<Pt>> 
+inline Unit dot(const Pt& a, const Pt& b) 
+{
+    return Unit(x(a)) * x(b) + Unit(y(a)) * y(b);
+}
+
+// squared vector magnitude
+template<class Pt, class Unit = TCompute<Pt>> 
+inline Unit magnsq(const Pt& p) 
+{
+    return  Unit(x(p)) * x(p) + Unit(y(p)) * y(p);
+}
+
+template<class RawPoint, class Unit = TCompute<RawPoint>>
+inline std::pair<Unit, bool> horizontalDistance(
         const RawPoint& p, const _Segment<RawPoint>& s)
 {
-    using Unit = TCoord<RawPoint>;
-    auto x = pointlike::x(p), y = pointlike::y(p);
-    auto x1 = pointlike::x(s.first()), y1 = pointlike::y(s.first());
-    auto x2 = pointlike::x(s.second()), y2 = pointlike::y(s.second());
+    namespace pl = pointlike;
+    auto x = Unit(pl::x(p)), y = Unit(pl::y(p));
+    auto x1 = Unit(pl::x(s.first())), y1 = Unit(pl::y(s.first()));
+    auto x2 = Unit(pl::x(s.second())), y2 = Unit(pl::y(s.second()));
 
-    TCoord<RawPoint> ret;
+    Unit ret;
 
     if( (y < y1 && y < y2) || (y > y1 && y > y2) )
         return {0, false};
@@ -250,8 +356,7 @@ inline std::pair<TCoord<RawPoint>, bool> horizontalDistance(
         ret = std::min( x-x1, x -x2);
     else if( (y == y1 && y == y2) && (x < x1 && x < x2))
         ret = -std::min(x1 - x, x2 - x);
-    else if(std::abs(y - y1) <= std::numeric_limits<Unit>::epsilon() &&
-            std::abs(y - y2) <= std::numeric_limits<Unit>::epsilon())
+    else if(y == y1 && y == y2)
         ret = 0;
     else
         ret = x - x1 + (x1 - x2)*(y1 - y)/(y1 - y2);
@@ -259,16 +364,16 @@ inline std::pair<TCoord<RawPoint>, bool> horizontalDistance(
     return {ret, true};
 }
 
-template<class RawPoint>
-inline std::pair<TCoord<RawPoint>, bool> verticalDistance(
+template<class RawPoint, class Unit = TCompute<RawPoint>>
+inline std::pair<Unit, bool> verticalDistance(
         const RawPoint& p, const _Segment<RawPoint>& s)
 {
-    using Unit = TCoord<RawPoint>;
-    auto x = pointlike::x(p), y = pointlike::y(p);
-    auto x1 = pointlike::x(s.first()), y1 = pointlike::y(s.first());
-    auto x2 = pointlike::x(s.second()), y2 = pointlike::y(s.second());
+    namespace pl = pointlike;
+    auto x = Unit(pl::x(p)), y = Unit(pl::y(p));
+    auto x1 = Unit(pl::x(s.first())), y1 = Unit(pl::y(s.first()));
+    auto x2 = Unit(pl::x(s.second())), y2 = Unit(pl::y(s.second()));
 
-    TCoord<RawPoint> ret;
+    Unit ret;
 
     if( (x < x1 && x < x2) || (x > x1 && x > x2) )
         return {0, false};
@@ -276,8 +381,7 @@ inline std::pair<TCoord<RawPoint>, bool> verticalDistance(
         ret = std::min( y-y1, y -y2);
     else if( (x == x1 && x == x2) && (y < y1 && y < y2))
         ret = -std::min(y1 - y, y2 - y);
-    else if(std::abs(x - x1) <= std::numeric_limits<Unit>::epsilon() &&
-            std::abs(x - x2) <= std::numeric_limits<Unit>::epsilon())
+    else if(x == x1 && x == x2)
         ret = 0;
     else
         ret = y - y1 + (y1 - y2)*(x1 - x)/(x1 - x2);
@@ -333,9 +437,10 @@ inline Radians _Segment<RawPoint>::angleToXaxis() const
 }
 
 template<class RawPoint>
-inline double _Segment<RawPoint>::length()
+template<class Unit>
+inline Unit _Segment<RawPoint>::sqlength() const
 {
-    return pointlike::distance(first(), second());
+    return pointlike::squaredDistance<RawPoint, Unit>(first(), second());
 }
 
 template<class RawPoint>
@@ -346,8 +451,8 @@ inline RawPoint _Box<RawPoint>::center() const BP2D_NOEXCEPT {
     using Coord = TCoord<RawPoint>;
 
     RawPoint ret =  { // No rounding here, we dont know if these are int coords
-        static_cast<Coord>( (getX(minc) + getX(maxc))/2.0 ),
-        static_cast<Coord>( (getY(minc) + getY(maxc))/2.0 )
+        Coord( (getX(minc) + getX(maxc)) / Coord(2) ),
+        Coord( (getY(minc) + getY(maxc)) / Coord(2) )
     };
 
     return ret;
@@ -362,9 +467,6 @@ enum class Formats {
 // used in friend declarations and can be aliased at class scope.
 namespace shapelike {
 
-template<class RawShape>
-using Shapes = TMultiShape<RawShape>;
-
 template<class RawShape>
 inline RawShape create(const TContour<RawShape>& contour,
                        const THolesContainer<RawShape>& holes)
@@ -449,7 +551,7 @@ inline void reserve(RawPath& p, size_t vertex_capacity, const PathTag&)
 template<class RawShape, class...Args>
 inline void addVertex(RawShape& sh, const PathTag&, Args...args)
 {
-    return sh.emplace_back(std::forward<Args>(args)...);
+    sh.emplace_back(std::forward<Args>(args)...);
 }
 
 template<class RawShape, class Fn>
@@ -504,13 +606,8 @@ inline void unserialize(RawShape& /*sh*/, const std::string& /*str*/)
                   "shapelike::unserialize() unimplemented!");
 }
 
-template<class RawShape>
-inline double area(const RawShape& /*sh*/, const PolygonTag&)
-{
-    static_assert(always_false<RawShape>::value,
-                  "shapelike::area() unimplemented!");
-    return 0;
-}
+template<class Cntr, class Unit = double>
+inline Unit area(const Cntr& poly, const PathTag& );
 
 template<class RawShape>
 inline bool intersects(const RawShape& /*sh*/, const RawShape& /*sh*/)
@@ -556,14 +653,14 @@ inline bool touches( const TPoint<RawShape>& /*point*/,
 
 template<class RawShape>
 inline _Box<TPoint<RawShape>> boundingBox(const RawShape& /*sh*/,
-                                          const PolygonTag&)
+                                          const PathTag&)
 {
     static_assert(always_false<RawShape>::value,
                   "shapelike::boundingBox(shape) unimplemented!");
 }
 
 template<class RawShapes>
-inline _Box<TPoint<typename RawShapes::value_type>>
+inline _Box<TPoint<RawShapes>>
 boundingBox(const RawShapes& /*sh*/, const MultiPolygonTag&)
 {
     static_assert(always_false<RawShapes>::value,
@@ -571,21 +668,10 @@ boundingBox(const RawShapes& /*sh*/, const MultiPolygonTag&)
 }
 
 template<class RawShape>
-inline RawShape convexHull(const RawShape& /*sh*/, const PolygonTag&)
-{
-    static_assert(always_false<RawShape>::value,
-                  "shapelike::convexHull(shape) unimplemented!");
-    return RawShape();
-}
+inline RawShape convexHull(const RawShape& sh, const PathTag&);
 
-template<class RawShapes>
-inline typename RawShapes::value_type
-convexHull(const RawShapes& /*sh*/, const MultiPolygonTag&)
-{
-    static_assert(always_false<RawShapes>::value,
-                  "shapelike::convexHull(shapes) unimplemented!");
-    return typename RawShapes::value_type();
-}
+template<class RawShapes, class S = typename RawShapes::value_type>
+inline S convexHull(const RawShapes& sh, const MultiPolygonTag&);
 
 template<class RawShape>
 inline void rotate(RawShape& /*sh*/, const Radians& /*rads*/)
@@ -745,13 +831,19 @@ inline void reserve(T& sh, size_t vertex_capacity) {
 template<class RawShape, class...Args>
 inline void addVertex(RawShape& sh, const PolygonTag&, Args...args)
 {
-    return addVertex(contour(sh), PathTag(), std::forward<Args>(args)...);
+    addVertex(contour(sh), PathTag(), std::forward<Args>(args)...);
 }
 
 template<class RawShape, class...Args> // Tag dispatcher
 inline void addVertex(RawShape& sh, Args...args)
 {
-    return addVertex(sh, Tag<RawShape>(), std::forward<Args>(args)...);
+    addVertex(sh, Tag<RawShape>(), std::forward<Args>(args)...);
+}
+
+template<class RawShape>
+inline _Box<TPoint<RawShape>> boundingBox(const RawShape& poly, const PolygonTag&)
+{
+    return boundingBox(contour(poly), PathTag());
 }
 
 template<class Box>
@@ -786,7 +878,7 @@ inline _Box<TPoint<S>> boundingBox(const S& sh)
 template<class Box>
 inline double area(const Box& box, const BoxTag& )
 {
-    return box.area();
+    return box.template area<double>();
 }
 
 template<class Circle>
@@ -795,6 +887,35 @@ inline double area(const Circle& circ, const CircleTag& )
     return circ.area();
 }
 
+template<class Cntr, class Unit>
+inline Unit area(const Cntr& poly, const PathTag& )
+{
+    namespace sl = shapelike;
+    if (sl::cend(poly) - sl::cbegin(poly) < 3) return 0.0;
+  
+    Unit a = 0;
+    for (auto i = sl::cbegin(poly), j = std::prev(sl::cend(poly)); 
+         i < sl::cend(poly); ++i)
+    {
+        auto xj = Unit(getX(*j)), yj = Unit(getY(*j));
+        auto xi = Unit(getX(*i)), yi = Unit(getY(*i));
+        a += (xj + xi) *  (yj - yi);
+        j = i;
+    }
+    a /= 2;
+    return is_clockwise<Cntr>() ? a : -a;
+}
+
+template<class S> inline double area(const S& poly, const PolygonTag& )
+{
+    auto hls = holes(poly);
+    return std::accumulate(hls.begin(), hls.end(), 
+                           area(contour(poly), PathTag()),
+                           [](double a, const TContour<S> &h){
+        return a + area(h, PathTag());    
+    });
+}
+
 template<class RawShape> // Dispatching function
 inline double area(const RawShape& sh)
 {
@@ -811,6 +932,12 @@ inline double area(const RawShapes& shapes, const MultiPolygonTag&)
     });
 }
 
+template<class RawShape>
+inline RawShape convexHull(const RawShape& sh, const PolygonTag&)
+{
+    return create<RawShape>(convexHull(contour(sh), PathTag()));
+}
+
 template<class RawShape>
 inline auto convexHull(const RawShape& sh)
     -> decltype(convexHull(sh, Tag<RawShape>())) // TODO: C++14 could deduce
@@ -818,11 +945,91 @@ inline auto convexHull(const RawShape& sh)
     return convexHull(sh, Tag<RawShape>());
 }
 
+template<class RawShape>
+inline RawShape convexHull(const RawShape& sh, const PathTag&)
+{
+    using Unit = TCompute<RawShape>;
+    using Point = TPoint<RawShape>;
+    namespace sl = shapelike;
+    
+    size_t edges = sl::cend(sh) - sl::cbegin(sh);
+    if(edges <= 3) return {};
+    
+    bool closed = false;
+    std::vector<Point> U, L;
+    U.reserve(1 + edges / 2); L.reserve(1 + edges / 2);
+    
+    std::vector<Point> pts; pts.reserve(edges);
+    std::copy(sl::cbegin(sh), sl::cend(sh), std::back_inserter(pts));
+    
+    auto fpt = pts.front(), lpt = pts.back();
+    if(getX(fpt) == getX(lpt) && getY(fpt) == getY(lpt)) { 
+        closed = true; pts.pop_back();
+    }
+    
+    std::sort(pts.begin(), pts.end(), 
+              [](const Point& v1, const Point& v2)
+    {
+        Unit x1 = getX(v1), x2 = getX(v2), y1 = getY(v1), y2 = getY(v2);
+        return x1 == x2 ? y1 < y2 : x1 < x2;
+    });
+    
+    auto dir = [](const Point& p, const Point& q, const Point& r) {
+        return (Unit(getY(q)) - getY(p)) * (Unit(getX(r)) - getX(p)) -
+               (Unit(getX(q)) - getX(p)) * (Unit(getY(r)) - getY(p));
+    };
+    
+    auto ik = pts.begin();
+    
+    while(ik != pts.end()) {
+        
+        while(U.size() > 1 && dir(U[U.size() - 2], U.back(), *ik) <= 0) 
+            U.pop_back();
+        while(L.size() > 1 && dir(L[L.size() - 2], L.back(), *ik) >= 0) 
+            L.pop_back();
+        
+        U.emplace_back(*ik);
+        L.emplace_back(*ik);
+        
+        ++ik;
+    }
+    
+    RawShape ret; reserve(ret, U.size() + L.size());
+    if(is_clockwise<RawShape>()) {
+        for(auto it = U.begin(); it != std::prev(U.end()); ++it) 
+            addVertex(ret, *it);  
+        for(auto it = L.rbegin(); it != std::prev(L.rend()); ++it) 
+            addVertex(ret, *it);
+        if(closed) addVertex(ret, *std::prev(L.rend()));
+    } else {
+        for(auto it = L.begin(); it != std::prev(L.end()); ++it) 
+            addVertex(ret, *it);  
+        for(auto it = U.rbegin(); it != std::prev(U.rend()); ++it) 
+            addVertex(ret, *it);  
+        if(closed) addVertex(ret, *std::prev(U.rend()));
+    }
+    
+    return ret;
+}
+
+template<class RawShapes, class S>
+inline S convexHull(const RawShapes& sh, const MultiPolygonTag&)
+{
+    namespace sl = shapelike;
+    S cntr;
+    for(auto& poly : sh) 
+        for(auto it = sl::cbegin(poly); it != sl::cend(poly); ++it) 
+            addVertex(cntr, *it);
+    
+    return convexHull(cntr, Tag<S>());
+}
+
 template<class TP, class TC>
 inline bool isInside(const TP& point, const TC& circ,
                      const PointTag&, const CircleTag&)
 {
-    return pointlike::distance(point, circ.center()) < circ.radius();
+    auto r = circ.radius();
+    return pointlike::squaredDistance(point, circ.center()) < r * r;
 }
 
 template<class TP, class TB>
@@ -972,6 +1179,9 @@ template<class RawShape> inline bool isConvex(const RawShape& sh) // dispatch
     using Segment = _Segment<Point>; \
     using Polygons = TMultiShape<T>
 
+namespace sl = shapelike;
+namespace pl = pointlike;
+
 }
 
 #endif // GEOMETRY_TRAITS_HPP
diff --git a/src/libnest2d/include/libnest2d/geometry_traits_nfp.hpp b/src/libnest2d/include/libnest2d/geometry_traits_nfp.hpp
index cb0580ef4..4a2c69bca 100644
--- a/src/libnest2d/include/libnest2d/geometry_traits_nfp.hpp
+++ b/src/libnest2d/include/libnest2d/geometry_traits_nfp.hpp
@@ -1,26 +1,22 @@
 #ifndef GEOMETRIES_NOFITPOLYGON_HPP
 #define GEOMETRIES_NOFITPOLYGON_HPP
 
-#include "geometry_traits.hpp"
 #include <algorithm>
 #include <functional>
 #include <vector>
 #include <iterator>
 
+#include <libnest2d/geometry_traits.hpp>
+
 namespace libnest2d {
 
 namespace __nfp {
 // Do not specialize this...
-template<class RawShape>
+template<class RawShape, class Unit = TCompute<RawShape>>
 inline bool _vsort(const TPoint<RawShape>& v1, const TPoint<RawShape>& v2)
 {
-    using Coord = TCoord<TPoint<RawShape>>;
-    Coord &&x1 = getX(v1), &&x2 = getX(v2), &&y1 = getY(v1), &&y2 = getY(v2);
-    auto diff = y1 - y2;
-    if(std::abs(diff) <= std::numeric_limits<Coord>::epsilon())
-        return x1 < x2;
-
-    return diff < 0;
+    Unit x1 = getX(v1), x2 = getX(v2), y1 = getY(v1), y2 = getY(v2);
+    return y1 == y2 ? x1 < x2 : y1 < y2;
 }
 
 template<class EdgeList, class RawShape, class Vertex = TPoint<RawShape>>
@@ -202,7 +198,7 @@ inline TPoint<RawShape> referenceVertex(const RawShape& sh)
  * convex as well in this case.
  *
  */
-template<class RawShape>
+template<class RawShape, class Ratio = double>
 inline NfpResult<RawShape> nfpConvexOnly(const RawShape& sh,
                                          const RawShape& other)
 {
@@ -238,12 +234,62 @@ inline NfpResult<RawShape> nfpConvexOnly(const RawShape& sh,
             ++first; ++next;
         }
     }
-
-    // Sort the edges by angle to X axis.
-    std::sort(edgelist.begin(), edgelist.end(),
-              [](const Edge& e1, const Edge& e2)
+   
+    std::sort(edgelist.begin(), edgelist.end(), 
+              [](const Edge& e1, const Edge& e2) 
     {
-        return e1.angleToXaxis() > e2.angleToXaxis();
+        Vertex ax(1, 0); // Unit vector for the X axis
+        
+        // get cectors from the edges
+        Vertex p1 = e1.second() - e1.first();
+        Vertex p2 = e2.second() - e2.first();
+
+        // Quadrant mapping array. The quadrant of a vector can be determined
+        // from the dot product of the vector and its perpendicular pair
+        // with the unit vector X axis. The products will carry the values
+        // lcos = dot(p, ax) = l * cos(phi) and
+        // lsin = -dotperp(p, ax) = l * sin(phi) where
+        // l is the length of vector p. From the signs of these values we can
+        // construct an index which has the sign of lcos as MSB and the
+        // sign of lsin as LSB. This index can be used to retrieve the actual
+        // quadrant where vector p resides using the following map:
+        // (+ is 0, - is 1)
+        // cos | sin | decimal | quadrant
+        //  +  |  +  |    0    |    0
+        //  +  |  -  |    1    |    3
+        //  -  |  +  |    2    |    1
+        //  -  |  -  |    3    |    2
+        std::array<int, 4> quadrants {0, 3, 1, 2 };
+
+        std::array<int, 2> q {0, 0}; // Quadrant indices for p1 and p2
+
+        using TDots = std::array<TCompute<Vertex>, 2>;
+        TDots lcos { pl::dot(p1, ax), pl::dot(p2, ax) };
+        TDots lsin { -pl::dotperp(p1, ax), -pl::dotperp(p2, ax) };
+
+        // Construct the quadrant indices for p1 and p2
+        for(size_t i = 0; i < 2; ++i)
+            if(lcos[i] == 0) q[i] = lsin[i] > 0 ? 1 : 3;
+            else if(lsin[i] == 0) q[i] = lcos[i] > 0 ? 0 : 2;
+            else q[i] = quadrants[((lcos[i] < 0) << 1) + (lsin[i] < 0)];
+            
+        if(q[0] == q[1]) { // only bother if p1 and p2 are in the same quadrant
+            auto lsq1 = pl::magnsq(p1);     // squared magnitudes, avoid sqrt
+            auto lsq2 = pl::magnsq(p2);     // squared magnitudes, avoid sqrt
+
+            // We will actually compare l^2 * cos^2(phi) which saturates the
+            // cos function. But with the quadrant info we can get the sign back
+            int sign = q[0] == 1 || q[0] == 2 ? -1 : 1;
+            
+            // If Ratio is an actual rational type, there is no precision loss
+            auto pcos1 = Ratio(lcos[0]) / lsq1 * sign * lcos[0];
+            auto pcos2 = Ratio(lcos[1]) / lsq2 * sign * lcos[1];
+            
+            return q[0] < 2 ? pcos1 < pcos2 : pcos1 > pcos2;
+        }
+        
+        // If in different quadrants, compare the quadrant indices only.
+        return q[0] > q[1];
     });
 
     __nfp::buildPolygon(edgelist, rsh, top_nfp);
@@ -253,456 +299,9 @@ inline NfpResult<RawShape> nfpConvexOnly(const RawShape& sh,
 
 template<class RawShape>
 NfpResult<RawShape> nfpSimpleSimple(const RawShape& cstationary,
-                                           const RawShape& cother)
+                                    const RawShape& cother)
 {
-
-    // Algorithms are from the original algorithm proposed in paper:
-    // https://eprints.soton.ac.uk/36850/1/CORMSIS-05-05.pdf
-
-    // /////////////////////////////////////////////////////////////////////////
-    // Algorithm 1: Obtaining the minkowski sum
-    // /////////////////////////////////////////////////////////////////////////
-
-    // I guess this is not a full minkowski sum of the two input polygons by
-    // definition. This yields a subset that is compatible with the next 2
-    // algorithms.
-
-    using Result = NfpResult<RawShape>;
-    using Vertex = TPoint<RawShape>;
-    using Coord = TCoord<Vertex>;
-    using Edge = _Segment<Vertex>;
-    namespace sl = shapelike;
-    using std::signbit;
-    using std::sort;
-    using std::vector;
-    using std::ref;
-    using std::reference_wrapper;
-
-    // TODO The original algorithms expects the stationary polygon in
-    // counter clockwise and the orbiter in clockwise order.
-    // So for preventing any further complication, I will make the input
-    // the way it should be, than make my way around the orientations.
-
-    // Reverse the stationary contour to counter clockwise
-    auto stcont = sl::contour(cstationary);
-    {
-        std::reverse(sl::begin(stcont), sl::end(stcont));
-        stcont.pop_back();
-        auto it = std::min_element(sl::begin(stcont), sl::end(stcont),
-                               [](const Vertex& v1, const Vertex& v2) {
-            return getY(v1) < getY(v2);
-        });
-        std::rotate(sl::begin(stcont), it, sl::end(stcont));
-        sl::addVertex(stcont, sl::front(stcont));
-    }
-    RawShape stationary;
-    sl::contour(stationary) = stcont;
-
-    // Reverse the orbiter contour to counter clockwise
-    auto orbcont = sl::contour(cother);
-    {
-        std::reverse(orbcont.begin(), orbcont.end());
-
-        // Step 1: Make the orbiter reverse oriented
-
-        orbcont.pop_back();
-        auto it = std::min_element(orbcont.begin(), orbcont.end(),
-                              [](const Vertex& v1, const Vertex& v2) {
-            return getY(v1) < getY(v2);
-        });
-
-        std::rotate(orbcont.begin(), it, orbcont.end());
-        orbcont.emplace_back(orbcont.front());
-
-        for(auto &v : orbcont) v = -v;
-
-    }
-
-    // Copy the orbiter (contour only), we will have to work on it
-    RawShape orbiter;
-    sl::contour(orbiter) = orbcont;
-
-    // An edge with additional data for marking it
-    struct MarkedEdge {
-        Edge e; Radians turn_angle = 0; bool is_turning_point = false;
-        MarkedEdge() = default;
-        MarkedEdge(const Edge& ed, Radians ta, bool tp):
-            e(ed), turn_angle(ta), is_turning_point(tp) {}
-
-        // debug
-        std::string label;
-    };
-
-    // Container for marked edges
-    using EdgeList = vector<MarkedEdge>;
-
-    EdgeList A, B;
-
-    // This is how an edge list is created from the polygons
-    auto fillEdgeList = [](EdgeList& L, const RawShape& ppoly, int dir) {
-        auto& poly = sl::contour(ppoly);
-
-        L.reserve(sl::contourVertexCount(poly));
-
-        if(dir > 0) {
-            auto it = poly.begin();
-            auto nextit = std::next(it);
-
-            double turn_angle = 0;
-            bool is_turn_point = false;
-
-            while(nextit != poly.end()) {
-                L.emplace_back(Edge(*it, *nextit), turn_angle, is_turn_point);
-                it++; nextit++;
-            }
-        } else {
-            auto it = sl::rbegin(poly);
-            auto nextit = std::next(it);
-
-            double turn_angle = 0;
-            bool is_turn_point = false;
-
-            while(nextit != sl::rend(poly)) {
-                L.emplace_back(Edge(*it, *nextit), turn_angle, is_turn_point);
-                it++; nextit++;
-            }
-        }
-
-        auto getTurnAngle = [](const Edge& e1, const Edge& e2) {
-            auto phi = e1.angleToXaxis();
-            auto phi_prev = e2.angleToXaxis();
-            auto turn_angle = phi-phi_prev;
-            if(turn_angle > Pi) turn_angle -= TwoPi;
-            if(turn_angle < -Pi) turn_angle += TwoPi;
-            return turn_angle;
-        };
-
-        auto eit = L.begin();
-        auto enext = std::next(eit);
-
-        eit->turn_angle = getTurnAngle(L.front().e, L.back().e);
-
-        while(enext != L.end()) {
-            enext->turn_angle = getTurnAngle( enext->e, eit->e);
-            eit->is_turning_point =
-                    signbit(enext->turn_angle) != signbit(eit->turn_angle);
-            ++eit; ++enext;
-        }
-
-        L.back().is_turning_point = signbit(L.back().turn_angle) !=
-                                    signbit(L.front().turn_angle);
-
-    };
-
-    // Step 2: Fill the edgelists
-    fillEdgeList(A, stationary, 1);
-    fillEdgeList(B, orbiter, 1);
-
-    int i = 1;
-    for(MarkedEdge& me : A) {
-        std::cout << "a" << i << ":\n\t"
-                  << getX(me.e.first()) << " " << getY(me.e.first()) << "\n\t"
-                  << getX(me.e.second()) << " " << getY(me.e.second()) << "\n\t"
-                  << "Turning point: " << (me.is_turning_point ? "yes" : "no")
-                  << std::endl;
-
-        me.label = "a"; me.label += std::to_string(i);
-        i++;
-    }
-
-    i = 1;
-    for(MarkedEdge& me : B) {
-        std::cout << "b" << i << ":\n\t"
-                  << getX(me.e.first()) << " " << getY(me.e.first()) << "\n\t"
-                  << getX(me.e.second()) << " " << getY(me.e.second()) << "\n\t"
-                  << "Turning point: " << (me.is_turning_point ? "yes" : "no")
-                  << std::endl;
-        me.label = "b"; me.label += std::to_string(i);
-        i++;
-    }
-
-    // A reference to a marked edge that also knows its container
-    struct MarkedEdgeRef {
-        reference_wrapper<MarkedEdge> eref;
-        reference_wrapper<vector<MarkedEdgeRef>> container;
-        Coord dir = 1;  // Direction modifier
-
-        inline Radians angleX() const { return eref.get().e.angleToXaxis(); }
-        inline const Edge& edge() const { return eref.get().e; }
-        inline Edge& edge() { return eref.get().e; }
-        inline bool isTurningPoint() const {
-            return eref.get().is_turning_point;
-        }
-        inline bool isFrom(const vector<MarkedEdgeRef>& cont ) {
-            return &(container.get()) == &cont;
-        }
-        inline bool eq(const MarkedEdgeRef& mr) {
-            return &(eref.get()) == &(mr.eref.get());
-        }
-
-        MarkedEdgeRef(reference_wrapper<MarkedEdge> er,
-                      reference_wrapper<vector<MarkedEdgeRef>> ec):
-            eref(er), container(ec), dir(1) {}
-
-        MarkedEdgeRef(reference_wrapper<MarkedEdge> er,
-                      reference_wrapper<vector<MarkedEdgeRef>> ec,
-                      Coord d):
-            eref(er), container(ec), dir(d) {}
-    };
-
-    using EdgeRefList = vector<MarkedEdgeRef>;
-
-    // Comparing two marked edges
-    auto sortfn = [](const MarkedEdgeRef& e1, const MarkedEdgeRef& e2) {
-        return e1.angleX() < e2.angleX();
-    };
-
-    EdgeRefList Aref, Bref;     // We create containers for the references
-    Aref.reserve(A.size()); Bref.reserve(B.size());
-
-    // Fill reference container for the stationary polygon
-    std::for_each(A.begin(), A.end(), [&Aref](MarkedEdge& me) {
-        Aref.emplace_back( ref(me), ref(Aref) );
-    });
-
-    // Fill reference container for the orbiting polygon
-    std::for_each(B.begin(), B.end(), [&Bref](MarkedEdge& me) {
-        Bref.emplace_back( ref(me), ref(Bref) );
-    });
-
-    auto mink = [sortfn] // the Mink(Q, R, direction) sub-procedure
-            (const EdgeRefList& Q, const EdgeRefList& R, bool positive)
-    {
-
-        // Step 1 "merge sort_list(Q) and sort_list(R) to form merge_list(Q,R)"
-        // Sort the containers of edge references and merge them.
-        // Q could be sorted only once and be reused here but we would still
-        // need to merge it with sorted(R).
-
-        EdgeRefList merged;
-        EdgeRefList S, seq;
-        merged.reserve(Q.size() + R.size());
-
-        merged.insert(merged.end(), R.begin(), R.end());
-        std::stable_sort(merged.begin(), merged.end(), sortfn);
-        merged.insert(merged.end(), Q.begin(), Q.end());
-        std::stable_sort(merged.begin(), merged.end(), sortfn);
-
-        // Step 2 "set i = 1, k = 1, direction = 1, s1 = q1"
-        // we don't use i, instead, q is an iterator into Q. k would be an index
-        // into the merged sequence but we use "it" as an iterator for that
-
-        // here we obtain references for the containers for later comparisons
-        const auto& Rcont = R.begin()->container.get();
-        const auto& Qcont = Q.begin()->container.get();
-
-        // Set the initial direction
-        Coord dir = 1;
-
-        // roughly i = 1 (so q = Q.begin()) and s1 = q1 so S[0] = q;
-        if(positive) {
-            auto q = Q.begin();
-            S.emplace_back(*q);
-
-            // Roughly step 3
-
-            std::cout << "merged size: " << merged.size() << std::endl;
-            auto mit = merged.begin();
-            for(bool finish = false; !finish && q != Q.end();) {
-                ++q; // "Set i = i + 1"
-
-                while(!finish && mit != merged.end()) {
-                    if(mit->isFrom(Rcont)) {
-                        auto s = *mit;
-                        s.dir = dir;
-                        S.emplace_back(s);
-                    }
-
-                    if(mit->eq(*q)) {
-                        S.emplace_back(*q);
-                        if(mit->isTurningPoint()) dir = -dir;
-                        if(q == Q.begin()) finish = true;
-                        break;
-                    }
-
-                    mit += dir;
-    //                __nfp::advance(mit, merged, dir > 0);
-                }
-            }
-        } else {
-            auto q = Q.rbegin();
-            S.emplace_back(*q);
-
-            // Roughly step 3
-
-            std::cout << "merged size: " << merged.size() << std::endl;
-            auto mit = merged.begin();
-            for(bool finish = false; !finish && q != Q.rend();) {
-                ++q; // "Set i = i + 1"
-
-                while(!finish && mit != merged.end()) {
-                    if(mit->isFrom(Rcont)) {
-                        auto s = *mit;
-                        s.dir = dir;
-                        S.emplace_back(s);
-                    }
-
-                    if(mit->eq(*q)) {
-                        S.emplace_back(*q);
-                        S.back().dir = -1;
-                        if(mit->isTurningPoint()) dir = -dir;
-                        if(q == Q.rbegin()) finish = true;
-                        break;
-                    }
-
-                    mit += dir;
-            //                __nfp::advance(mit, merged, dir > 0);
-                }
-            }
-        }
-
-
-        // Step 4:
-
-        // "Let starting edge r1 be in position si in sequence"
-        // whaaat? I guess this means the following:
-        auto it = S.begin();
-        while(!it->eq(*R.begin())) ++it;
-
-        // "Set j = 1, next = 2, direction = 1, seq1 = si"
-        // we don't use j, seq is expanded dynamically.
-        dir = 1;
-        auto next = std::next(R.begin()); seq.emplace_back(*it);
-
-        // Step 5:
-        // "If all si edges have been allocated to seqj" should mean that
-        // we loop until seq has equal size with S
-        auto send = it; //it == S.begin() ? it : std::prev(it);
-        while(it != S.end()) {
-            ++it; if(it == S.end()) it = S.begin();
-            if(it == send) break;
-
-            if(it->isFrom(Qcont)) {
-                seq.emplace_back(*it); // "If si is from Q, j = j + 1, seqj = si"
-
-                // "If si is a turning point in Q,
-                // direction = - direction, next = next + direction"
-                if(it->isTurningPoint()) {
-                    dir = -dir;
-                    next += dir;
-//                    __nfp::advance(next, R, dir > 0);
-                }
-            }
-
-            if(it->eq(*next) /*&& dir == next->dir*/) { // "If si = direction.rnext"
-                // "j = j + 1, seqj = si, next = next + direction"
-                seq.emplace_back(*it);
-                next += dir;
-//                __nfp::advance(next, R, dir > 0);
-            }
-        }
-
-        return seq;
-    };
-
-    std::vector<EdgeRefList> seqlist;
-    seqlist.reserve(Bref.size());
-
-    EdgeRefList Bslope = Bref;  // copy Bref, we will make a slope diagram
-
-    // make the slope diagram of B
-    std::sort(Bslope.begin(), Bslope.end(), sortfn);
-
-    auto slopeit = Bslope.begin(); // search for the first turning point
-    while(!slopeit->isTurningPoint() && slopeit != Bslope.end()) slopeit++;
-
-    if(slopeit == Bslope.end()) {
-        // no turning point means convex polygon.
-        seqlist.emplace_back(mink(Aref, Bref, true));
-    } else {
-        int dir = 1;
-
-        auto firstturn = Bref.begin();
-        while(!firstturn->eq(*slopeit)) ++firstturn;
-
-        assert(firstturn != Bref.end());
-
-        EdgeRefList bgroup; bgroup.reserve(Bref.size());
-        bgroup.emplace_back(*slopeit);
-
-        auto b_it = std::next(firstturn);
-        while(b_it != firstturn) {
-            if(b_it == Bref.end()) b_it = Bref.begin();
-
-            while(!slopeit->eq(*b_it)) {
-                __nfp::advance(slopeit, Bslope, dir > 0);
-            }
-
-            if(!slopeit->isTurningPoint()) {
-                bgroup.emplace_back(*slopeit);
-            } else {
-                if(!bgroup.empty()) {
-                    if(dir > 0) bgroup.emplace_back(*slopeit);
-                    for(auto& me : bgroup) {
-                        std::cout << me.eref.get().label << ", ";
-                    }
-                    std::cout << std::endl;
-                    seqlist.emplace_back(mink(Aref, bgroup, dir == 1 ? true : false));
-                    bgroup.clear();
-                    if(dir < 0) bgroup.emplace_back(*slopeit);
-                } else {
-                    bgroup.emplace_back(*slopeit);
-                }
-
-                dir *= -1;
-            }
-            ++b_it;
-        }
-    }
-
-//    while(it != Bref.end()) // This is step 3 and step 4 in one loop
-//        if(it->isTurningPoint()) {
-//            R = {R.last, it++};
-//            auto seq = mink(Q, R, orientation);
-
-//            // TODO step 6 (should be 5 shouldn't it?): linking edges from A
-//            // I don't get this step
-
-//            seqlist.insert(seqlist.end(), seq.begin(), seq.end());
-//            orientation = !orientation;
-//        } else ++it;
-
-//    if(seqlist.empty()) seqlist = mink(Q, {Bref.begin(), Bref.end()}, true);
-
-    // /////////////////////////////////////////////////////////////////////////
-    // Algorithm 2: breaking Minkowski sums into track line trips
-    // /////////////////////////////////////////////////////////////////////////
-
-
-    // /////////////////////////////////////////////////////////////////////////
-    // Algorithm 3: finding the boundary of the NFP from track line trips
-    // /////////////////////////////////////////////////////////////////////////
-
-
-    for(auto& seq : seqlist) {
-        std::cout << "seqlist size: " << seq.size() << std::endl;
-        for(auto& s : seq) {
-            std::cout << (s.dir > 0 ? "" : "-") << s.eref.get().label << ", ";
-        }
-        std::cout << std::endl;
-    }
-
-    auto& seq = seqlist.front();
-    RawShape rsh;
-    Vertex top_nfp;
-    std::vector<Edge> edgelist; edgelist.reserve(seq.size());
-    for(auto& s : seq) {
-        edgelist.emplace_back(s.eref.get().e);
-    }
-
-    __nfp::buildPolygon(edgelist, rsh, top_nfp);
-
-    return Result(rsh, top_nfp);
+    return {};
 }
 
 // Specializable NFP implementation class. Specialize it if you have a faster
diff --git a/src/libnest2d/include/libnest2d/libnest2d.hpp b/src/libnest2d/include/libnest2d/libnest2d.hpp
index c7b252e5d..5d74aa3d9 100644
--- a/src/libnest2d/include/libnest2d/libnest2d.hpp
+++ b/src/libnest2d/include/libnest2d/libnest2d.hpp
@@ -8,13 +8,10 @@
 #include <algorithm>
 #include <functional>
 
-#include "geometry_traits.hpp"
+#include <libnest2d/geometry_traits.hpp>
 
 namespace libnest2d {
 
-namespace sl = shapelike;
-namespace pl = pointlike;
-
 /**
  * \brief An item to be placed on a bin.
  *
@@ -422,13 +419,9 @@ private:
 
     static inline bool vsort(const Vertex& v1, const Vertex& v2)
     {
-        Coord &&x1 = getX(v1), &&x2 = getX(v2);
-        Coord &&y1 = getY(v1), &&y2 = getY(v2);
-        auto diff = y1 - y2;
-        if(std::abs(diff) <= std::numeric_limits<Coord>::epsilon())
-            return x1 < x2;
-
-        return diff < 0;
+        TCompute<Vertex> x1 = getX(v1), x2 = getX(v2);
+        TCompute<Vertex> y1 = getY(v1), y2 = getY(v2);
+        return y1 == y2 ? x1 < x2 : y1 < y2;
     }
 };
 
diff --git a/src/libnest2d/include/libnest2d/optimizer.hpp b/src/libnest2d/include/libnest2d/optimizer.hpp
index 962a47392..e4c149f22 100644
--- a/src/libnest2d/include/libnest2d/optimizer.hpp
+++ b/src/libnest2d/include/libnest2d/optimizer.hpp
@@ -4,7 +4,8 @@
 #include <tuple>
 #include <functional>
 #include <limits>
-#include "common.hpp"
+
+#include <libnest2d/common.hpp>
 
 namespace libnest2d { namespace opt {
 
@@ -60,6 +61,7 @@ enum class Method {
     L_SIMPLEX,
     L_SUBPLEX,
     G_GENETIC,
+    G_PARTICLE_SWARM
     //...
 };
 
diff --git a/src/libnest2d/include/libnest2d/optimizers/nlopt/CMakeLists.txt b/src/libnest2d/include/libnest2d/optimizers/nlopt/CMakeLists.txt
index 4e16d4fc5..6f51718d8 100644
--- a/src/libnest2d/include/libnest2d/optimizers/nlopt/CMakeLists.txt
+++ b/src/libnest2d/include/libnest2d/optimizers/nlopt/CMakeLists.txt
@@ -48,7 +48,7 @@ else()
     target_link_libraries(nloptOptimizer INTERFACE Nlopt::Nlopt)
 endif()
 
-#target_sources( NloptOptimizer INTERFACE
+#target_sources( nloptOptimizer INTERFACE
 #${CMAKE_CURRENT_SOURCE_DIR}/simplex.hpp
 #${CMAKE_CURRENT_SOURCE_DIR}/subplex.hpp
 #${CMAKE_CURRENT_SOURCE_DIR}/genetic.hpp
@@ -57,5 +57,5 @@ endif()
 
 target_compile_definitions(nloptOptimizer INTERFACE LIBNEST2D_OPTIMIZER_NLOPT)
 
-# And finally plug the NloptOptimizer into libnest2d
-#target_link_libraries(libnest2d INTERFACE NloptOptimizer)
+# And finally plug the nloptOptimizer into libnest2d
+#target_link_libraries(libnest2d INTERFACE nloptOptimizer)
diff --git a/src/libnest2d/include/libnest2d/optimizers/optimlib/CMakeLists.txt b/src/libnest2d/include/libnest2d/optimizers/optimlib/CMakeLists.txt
deleted file mode 100644
index efbbd9cfb..000000000
--- a/src/libnest2d/include/libnest2d/optimizers/optimlib/CMakeLists.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-find_package(Armadillo REQUIRED)
-
-add_library(OptimlibOptimizer INTERFACE)
-target_include_directories(OptimlibOptimizer INTERFACE ${ARMADILLO_INCLUDE_DIRS})
-target_link_libraries(OptimlibOptimizer INTERFACE ${ARMADILLO_LIBRARIES})
\ No newline at end of file
diff --git a/src/libnest2d/include/libnest2d/placers/bottomleftplacer.hpp b/src/libnest2d/include/libnest2d/placers/bottomleftplacer.hpp
index 7f10be7d7..28aaad5ce 100644
--- a/src/libnest2d/include/libnest2d/placers/bottomleftplacer.hpp
+++ b/src/libnest2d/include/libnest2d/placers/bottomleftplacer.hpp
@@ -7,15 +7,15 @@
 
 namespace libnest2d { namespace placers {
 
-template<class T, class = T> struct Epsilon {};
+template<class T, class = T> struct DefaultEpsilon {};
 
 template<class T>
-struct Epsilon<T, enable_if_t<std::is_integral<T>::value, T> > {
+struct DefaultEpsilon<T, enable_if_t<std::is_integral<T>::value, T> > {
     static const T Value = 1;
 };
 
 template<class T>
-struct Epsilon<T, enable_if_t<std::is_floating_point<T>::value, T> > {
+struct DefaultEpsilon<T, enable_if_t<std::is_floating_point<T>::value, T> > {
     static const T Value = 1e-3;
 };
 
@@ -24,7 +24,7 @@ struct BLConfig {
     DECLARE_MAIN_TYPES(RawShape);
 
     Coord min_obj_distance = 0;
-    Coord epsilon = Epsilon<Coord>::Value;
+    Coord epsilon = DefaultEpsilon<Coord>::Value;
     bool allow_rotations = false;
 };
 
diff --git a/src/libnest2d/include/libnest2d/placers/nfpplacer.hpp b/src/libnest2d/include/libnest2d/placers/nfpplacer.hpp
index 91affe978..c1f15fe61 100644
--- a/src/libnest2d/include/libnest2d/placers/nfpplacer.hpp
+++ b/src/libnest2d/include/libnest2d/placers/nfpplacer.hpp
@@ -103,14 +103,14 @@ Key hash(const _Item<S>& item) {
         while(deg > N) { ms++; deg -= N; }
         ls += int(deg);
         ret.push_back(char(ms)); ret.push_back(char(ls));
-        circ += seg.length();
+        circ += std::sqrt(seg.template sqlength<double>());
     }
 
     it = ctr.begin(); nx = std::next(it);
 
     while(nx != ctr.end()) {
         Segment seg(*it++, *nx++);
-        auto l = int(M * seg.length() / circ);
+        auto l = int(M * std::sqrt(seg.template sqlength<double>()) / circ);
         int ms = 'A', ls = 'A';
         while(l > N) { ms++; l -= N; }
         ls += l;
@@ -249,6 +249,11 @@ template<class RawShape> class EdgeCache {
     std::vector<ContourCache> holes_;
 
     double accuracy_ = 1.0;
+    
+    static double length(const Edge &e) 
+    { 
+        return std::sqrt(e.template sqlength<double>());
+    }
 
     void createCache(const RawShape& sh) {
         {   // For the contour
@@ -260,7 +265,7 @@ template<class RawShape> class EdgeCache {
 
             while(next != endit) {
                 contour_.emap.emplace_back(*(first++), *(next++));
-                contour_.full_distance += contour_.emap.back().length();
+                contour_.full_distance += length(contour_.emap.back());
                 contour_.distances.emplace_back(contour_.full_distance);
             }
         }
@@ -275,7 +280,7 @@ template<class RawShape> class EdgeCache {
 
             while(next != endit) {
                 hc.emap.emplace_back(*(first++), *(next++));
-                hc.full_distance += hc.emap.back().length();
+                hc.full_distance += length(hc.emap.back());
                 hc.distances.emplace_back(hc.full_distance);
             }
 
diff --git a/src/libnest2d/include/libnest2d/utils/boost_alg.hpp b/src/libnest2d/include/libnest2d/utils/boost_alg.hpp
index baf1c6a10..16dee513b 100644
--- a/src/libnest2d/include/libnest2d/utils/boost_alg.hpp
+++ b/src/libnest2d/include/libnest2d/utils/boost_alg.hpp
@@ -311,19 +311,19 @@ struct range_value<bp2d::Shapes> {
 
 namespace libnest2d { // Now the algorithms that boost can provide...
 
-namespace pointlike {
-template<>
-inline double distance(const PointImpl& p1, const PointImpl& p2 )
-{
-    return boost::geometry::distance(p1, p2);
-}
+//namespace pointlike {
+//template<>
+//inline double distance(const PointImpl& p1, const PointImpl& p2 )
+//{
+//    return boost::geometry::distance(p1, p2);
+//}
 
-template<>
-inline double distance(const PointImpl& p, const bp2d::Segment& seg )
-{
-    return boost::geometry::distance(p, seg);
-}
-}
+//template<>
+//inline double distance(const PointImpl& p, const bp2d::Segment& seg )
+//{
+//    return boost::geometry::distance(p, seg);
+//}
+//}
 
 namespace shapelike {
 // Tell libnest2d how to make string out of a ClipperPolygon object
@@ -382,16 +382,9 @@ inline bool touches( const PointImpl& point, const PolygonImpl& shape)
 }
 
 #ifndef DISABLE_BOOST_BOUNDING_BOX
-template<>
-inline bp2d::Box boundingBox(const PolygonImpl& sh, const PolygonTag&)
-{
-    bp2d::Box b;
-    boost::geometry::envelope(sh, b);
-    return b;
-}
 
 template<>
-inline bp2d::Box boundingBox(const PathImpl& sh, const PolygonTag&)
+inline bp2d::Box boundingBox(const PathImpl& sh, const PathTag&)
 {
     bp2d::Box b;
     boost::geometry::envelope(sh, b);
@@ -410,9 +403,9 @@ inline bp2d::Box boundingBox<bp2d::Shapes>(const bp2d::Shapes& shapes,
 
 #ifndef DISABLE_BOOST_CONVEX_HULL
 template<>
-inline PolygonImpl convexHull(const PolygonImpl& sh, const PolygonTag&)
+inline PathImpl convexHull(const PathImpl& sh, const PathTag&)
 {
-    PolygonImpl ret;
+    PathImpl ret;
     boost::geometry::convex_hull(sh, ret);
     return ret;
 }
diff --git a/src/libnest2d/include/libnest2d/utils/rotcalipers.hpp b/src/libnest2d/include/libnest2d/utils/rotcalipers.hpp
new file mode 100644
index 000000000..76f91ba0c
--- /dev/null
+++ b/src/libnest2d/include/libnest2d/utils/rotcalipers.hpp
@@ -0,0 +1,268 @@
+#ifndef ROTCALIPERS_HPP
+#define ROTCALIPERS_HPP
+
+#include <numeric>
+#include <functional>
+#include <array>
+#include <cmath>
+
+#include <libnest2d/geometry_traits.hpp>
+
+namespace libnest2d {
+
+template<class Pt, class Unit = TCompute<Pt>> class RotatedBox {
+    Pt axis_;
+    Unit bottom_ = Unit(0), right_ = Unit(0);
+public:
+    
+    RotatedBox() = default;
+    RotatedBox(const Pt& axis, Unit b, Unit r):
+        axis_(axis), bottom_(b), right_(r) {}
+    
+    inline long double area() const { 
+        long double asq = pl::magnsq<Pt, long double>(axis_);
+        return cast<long double>(bottom_) * cast<long double>(right_) / asq;
+    }
+    
+    inline long double width() const { 
+        return abs(bottom_) / std::sqrt(pl::magnsq<Pt, long double>(axis_));
+    }
+    
+    inline long double height() const { 
+        return abs(right_) / std::sqrt(pl::magnsq<Pt, long double>(axis_));
+    }
+    
+    inline Unit bottom_extent() const { return bottom_; }
+    inline Unit right_extent() const { return right_;  }
+    inline const Pt& axis() const { return axis_; }
+    
+    inline Radians angleToX() const {
+        double ret = std::atan2(getY(axis_), getX(axis_));
+        auto s = std::signbit(ret);
+        if(s) ret += Pi_2;
+        return -ret;
+    }
+};
+
+template <class Poly, class Pt = TPoint<Poly>, class Unit = TCompute<Pt>> 
+Poly removeCollinearPoints(const Poly& sh, Unit eps = Unit(0))
+{
+    Poly ret; sl::reserve(ret, sl::contourVertexCount(sh));
+    
+    Pt eprev = *sl::cbegin(sh) - *std::prev(sl::cend(sh));
+    
+    auto it  = sl::cbegin(sh);
+    auto itx = std::next(it);
+    if(itx != sl::cend(sh)) while (it != sl::cend(sh))
+    {
+        Pt enext = *itx - *it;
+
+        auto dp = pl::dotperp<Pt, Unit>(eprev, enext);
+        if(abs(dp) > eps) sl::addVertex(ret, *it);
+        
+        eprev = enext;
+        if (++itx == sl::cend(sh)) itx = sl::cbegin(sh);
+        ++it;
+    }
+    
+    return ret;
+}
+
+// The area of the bounding rectangle with the axis dir and support vertices
+template<class Pt, class Unit = TCompute<Pt>, class R = TCompute<Pt>> 
+inline R rectarea(const Pt& w, // the axis
+                  const Pt& vb, const Pt& vr, 
+                  const Pt& vt, const Pt& vl) 
+{
+    Unit a = pl::dot<Pt, Unit>(w, vr - vl); 
+    Unit b = pl::dot<Pt, Unit>(-pl::perp(w), vt - vb);
+    R m = R(a) / pl::magnsq<Pt, Unit>(w);
+    m = m * b;
+    return m;
+};
+
+template<class Pt, 
+         class Unit = TCompute<Pt>,
+         class R = TCompute<Pt>,
+         class It = typename std::vector<Pt>::const_iterator>
+inline R rectarea(const Pt& w, const std::array<It, 4>& rect)
+{
+    return rectarea<Pt, Unit, R>(w, *rect[0], *rect[1], *rect[2], *rect[3]);
+}
+
+// This function is only applicable to counter-clockwise oriented convex
+// polygons where only two points can be collinear witch each other.
+template <class RawShape, 
+          class Unit = TCompute<RawShape>, 
+          class Ratio = TCompute<RawShape>> 
+RotatedBox<TPoint<RawShape>, Unit> minAreaBoundingBox(const RawShape& sh) 
+{
+    using Point = TPoint<RawShape>;
+    using Iterator = typename TContour<RawShape>::const_iterator;
+    using pointlike::dot; using pointlike::magnsq; using pointlike::perp;
+
+    // Get the first and the last vertex iterator
+    auto first = sl::cbegin(sh);
+    auto last = std::prev(sl::cend(sh));
+    
+    // Check conditions and return undefined box if input is not sane.
+    if(last == first) return {};
+    if(getX(*first) == getX(*last) && getY(*first) == getY(*last)) --last;
+    if(last - first < 2) return {};
+    
+    RawShape shcpy; // empty at this point
+    {   
+        Point p = *first, q = *std::next(first), r = *last;
+        
+        // Determine orientation from first 3 vertex (should be consistent)
+        Unit d = (Unit(getY(q)) - getY(p)) * (Unit(getX(r)) - getX(p)) -
+                 (Unit(getX(q)) - getX(p)) * (Unit(getY(r)) - getY(p));
+        
+        if(d > 0) { 
+            // The polygon is clockwise. A flip is needed (for now)
+            sl::reserve(shcpy, last - first);
+            auto it = last; while(it != first) sl::addVertex(shcpy, *it--);
+            sl::addVertex(shcpy, *first);
+            first = sl::cbegin(shcpy); last = std::prev(sl::cend(shcpy));
+        }
+    }
+    
+    // Cyclic iterator increment
+    auto inc = [&first, &last](Iterator& it) {
+       if(it == last) it = first; else ++it;
+    };
+    
+    // Cyclic previous iterator
+    auto prev = [&first, &last](Iterator it) { 
+        return it == first ? last : std::prev(it); 
+    };
+    
+    // Cyclic next iterator
+    auto next = [&first, &last](Iterator it) {
+        return it == last ? first : std::next(it);    
+    };
+    
+    // Establish initial (axis aligned) rectangle support verices by determining 
+    // polygon extremes:
+    
+    auto it = first;
+    Iterator minX = it, maxX = it, minY = it, maxY = it;
+    
+    do { // Linear walk through the vertices and save the extreme positions
+        
+        Point v = *it, d = v - *minX;
+        if(getX(d) < 0 || (getX(d) == 0 && getY(d) < 0)) minX = it;
+        
+        d = v - *maxX;
+        if(getX(d) > 0 || (getX(d) == 0 && getY(d) > 0)) maxX = it;
+        
+        d = v - *minY;
+        if(getY(d) < 0 || (getY(d) == 0 && getX(d) > 0)) minY = it;
+        
+        d = v - *maxY;
+        if(getY(d) > 0 || (getY(d) == 0 && getX(d) < 0)) maxY = it;
+        
+    } while(++it != std::next(last));
+    
+    // Update the vertices defining the bounding rectangle. The rectangle with
+    // the smallest rotation is selected and the supporting vertices are 
+    // returned in the 'rect' argument.
+    auto update = [&next, &inc]
+            (const Point& w, std::array<Iterator, 4>& rect) 
+    {
+        Iterator B = rect[0], Bn = next(B);
+        Iterator R = rect[1], Rn = next(R);
+        Iterator T = rect[2], Tn = next(T);
+        Iterator L = rect[3], Ln = next(L);
+        
+        Point b = *Bn - *B, r = *Rn - *R, t = *Tn - *T, l = *Ln - *L;
+        Point pw = perp(w);
+        using Pt = Point;
+        
+        Unit dotwpb = dot<Pt, Unit>( w, b), dotwpr = dot<Pt, Unit>(-pw, r);
+        Unit dotwpt = dot<Pt, Unit>(-w, t), dotwpl = dot<Pt, Unit>( pw, l);
+        Unit dw     = magnsq<Pt, Unit>(w);
+        
+        std::array<Ratio, 4> angles;
+        angles[0] = (Ratio(dotwpb) / magnsq<Pt, Unit>(b)) * dotwpb;
+        angles[1] = (Ratio(dotwpr) / magnsq<Pt, Unit>(r)) * dotwpr;
+        angles[2] = (Ratio(dotwpt) / magnsq<Pt, Unit>(t)) * dotwpt;
+        angles[3] = (Ratio(dotwpl) / magnsq<Pt, Unit>(l)) * dotwpl;
+        
+        using AngleIndex = std::pair<Ratio, size_t>;
+        std::vector<AngleIndex> A; A.reserve(4);
+
+        for (size_t i = 3, j = 0; j < 4; i = j++) {
+            if(rect[i] != rect[j] && angles[i] < dw) {
+                auto iv = std::make_pair(angles[i], i);
+                auto it = std::lower_bound(A.begin(), A.end(), iv,
+                                           [](const AngleIndex& ai, 
+                                              const AngleIndex& aj) 
+                { 
+                    return ai.first > aj.first; 
+                });
+                
+                A.insert(it, iv);
+            }
+        }
+        
+        // The polygon is supposed to be a rectangle.
+        if(A.empty()) return false;
+       
+        auto amin = A.front().first;
+        auto imin = A.front().second;
+        for(auto& a : A) if(a.first == amin) inc(rect[a.second]);
+            
+        std::rotate(rect.begin(), rect.begin() + imin, rect.end());
+        
+        return true;
+    };
+    
+    Point w(1, 0);
+    Point w_min = w;
+    Ratio minarea((Unit(getX(*maxX)) - getX(*minX)) * 
+                  (Unit(getY(*maxY)) - getY(*minY)));
+    
+    std::array<Iterator, 4> rect = {minY, maxX, maxY, minX};
+    std::array<Iterator, 4> minrect = rect;
+    
+    // An edge might be examined twice in which case the algorithm terminates.
+    size_t c = 0, count = last - first + 1;
+    std::vector<bool> edgemask(count, false);
+    
+    while(c++ < count) 
+    {   
+        // Update the support vertices, if cannot be updated, break the cycle.
+        if(! update(w, rect)) break;
+        
+        size_t eidx = size_t(rect[0] - first);
+        
+        if(edgemask[eidx]) break;
+        edgemask[eidx] = true;
+                
+        // get the unnormalized direction vector
+        w = *rect[0] - *prev(rect[0]);
+        
+        // get the area of the rotated rectangle
+        Ratio rarea = rectarea<Point, Unit, Ratio>(w, rect);
+        
+        // Update min area and the direction of the min bounding box;
+        if(rarea <= minarea) { w_min = w; minarea = rarea; minrect = rect; }
+    }
+    
+    Unit a = dot<Point, Unit>(w_min, *minrect[1] - *minrect[3]);
+    Unit b = dot<Point, Unit>(-perp(w_min), *minrect[2] - *minrect[0]);
+    RotatedBox<Point, Unit> bb(w_min, a, b);
+    
+    return bb;
+}
+
+template <class RawShape> Radians minAreaBoundingBoxRotation(const RawShape& sh)
+{
+    return minAreaBoundingBox(sh).angleToX();
+}
+
+
+}
+
+#endif // ROTCALIPERS_HPP
diff --git a/src/libnest2d/src/libnest2d.cpp b/src/libnest2d/src/libnest2d.cpp
new file mode 100644
index 000000000..021458787
--- /dev/null
+++ b/src/libnest2d/src/libnest2d.cpp
@@ -0,0 +1,23 @@
+#include <libnest2d.h>
+
+namespace libnest2d {
+
+template class Nester<NfpPlacer, FirstFitSelection>;
+template class Nester<BottomLeftPlacer, FirstFitSelection>;
+
+template PackGroup nest(std::vector<Item>::iterator from, 
+                        std::vector<Item>::iterator to,
+                        const Box& bin,
+                        Coord dist = 0,
+                        const NfpPlacer::Config& pconf,
+                        const FirstFitSelection::Config& sconf);
+
+template PackGroup nest(std::vector<Item>::iterator from, 
+                        std::vector<Item>::iterator to,
+                        const Box& bin,
+                        ProgressFunction prg,
+                        StopCondition scond,
+                        Coord dist = 0,
+                        const NfpPlacer::Config& pconf,
+                        const FirstFitSelection::Config& sconf);
+}
diff --git a/src/libnest2d/tests/CMakeLists.txt b/src/libnest2d/tests/CMakeLists.txt
index fc3cd309d..1b7d8e3ae 100644
--- a/src/libnest2d/tests/CMakeLists.txt
+++ b/src/libnest2d/tests/CMakeLists.txt
@@ -49,7 +49,12 @@ add_executable(tests_clipper_nlopt
 
 target_link_libraries(tests_clipper_nlopt libnest2d ${GTEST_LIBS_TO_LINK} )
 
-target_include_directories(tests_clipper_nlopt PRIVATE BEFORE
-    ${GTEST_INCLUDE_DIRS})
+target_include_directories(tests_clipper_nlopt PRIVATE BEFORE ${GTEST_INCLUDE_DIRS})
+
+if(NOT LIBNEST2D_HEADER_ONLY)
+    target_link_libraries(tests_clipper_nlopt ${LIBNAME})
+else()
+    target_link_libraries(tests_clipper_nlopt libnest2d)
+endif()
 
 add_test(libnest2d_tests tests_clipper_nlopt)
diff --git a/src/libnest2d/tests/test.cpp b/src/libnest2d/tests/test.cpp
index 3b0eae161..5741e87b4 100644
--- a/src/libnest2d/tests/test.cpp
+++ b/src/libnest2d/tests/test.cpp
@@ -3,11 +3,43 @@
 
 #include <libnest2d.h>
 #include "printer_parts.h"
-#include <libnest2d/geometry_traits_nfp.hpp>
+//#include <libnest2d/geometry_traits_nfp.hpp>
 #include "../tools/svgtools.hpp"
+#include <libnest2d/utils/rotcalipers.hpp>
+
+#include "boost/multiprecision/integer.hpp"
+#include "boost/rational.hpp"
+
+//#include "../tools/Int128.hpp"
+
+//#include "gte/Mathematics/GteMinimumAreaBox2.h"
+
 //#include "../tools/libnfpglue.hpp"
 //#include "../tools/nfp_svgnest_glue.hpp"
 
+namespace libnest2d {
+#if !defined(_MSC_VER) && defined(__SIZEOF_INT128__) && !defined(__APPLE__)
+using LargeInt = __int128;
+#else
+using LargeInt = boost::multiprecision::int128_t;
+template<> struct _NumTag<LargeInt> { using Type = ScalarTag; };
+#endif
+template<class T> struct _NumTag<boost::rational<T>> { using Type = RationalTag; };
+
+namespace nfp {
+
+template<class S>
+struct NfpImpl<S, NfpLevel::CONVEX_ONLY>
+{
+    NfpResult<S> operator()(const S &sh, const S &other)
+    {
+        return nfpConvexOnly<S, boost::rational<LargeInt>>(sh, other);
+    }
+};
+
+}
+}
+
 std::vector<libnest2d::Item>& prusaParts() {
     static std::vector<libnest2d::Item> ret;
 
@@ -31,8 +63,8 @@ TEST(BasicFunctionality, Angles)
     ASSERT_DOUBLE_EQ(rad, Pi);
     ASSERT_DOUBLE_EQ(deg, 180);
     ASSERT_DOUBLE_EQ(deg2, 180);
-    ASSERT_DOUBLE_EQ(rad, (Radians) deg);
-    ASSERT_DOUBLE_EQ( (Degrees) rad, deg);
+    ASSERT_DOUBLE_EQ(rad, Radians(deg));
+    ASSERT_DOUBLE_EQ( Degrees(rad), deg);
 
     ASSERT_TRUE(rad == deg);
 
@@ -151,12 +183,12 @@ TEST(GeometryAlgorithms, Distance) {
 
     Segment seg(p1, p3);
 
-    ASSERT_DOUBLE_EQ(pointlike::distance(p2, seg), 7.0710678118654755);
+//    ASSERT_DOUBLE_EQ(pointlike::distance(p2, seg), 7.0710678118654755);
 
     auto result = pointlike::horizontalDistance(p2, seg);
 
-    auto check = [](Coord val, Coord expected) {
-        if(std::is_floating_point<Coord>::value)
+    auto check = [](TCompute<Coord> val, TCompute<Coord> expected) {
+        if(std::is_floating_point<TCompute<Coord>>::value)
             ASSERT_DOUBLE_EQ(static_cast<double>(val),
                              static_cast<double>(expected));
         else
@@ -415,7 +447,7 @@ TEST(GeometryAlgorithms, ArrangeRectanglesLoose)
 namespace {
 using namespace libnest2d;
 
-template<unsigned long SCALE = 1, class Bin>
+template<long long SCALE = 1, class Bin>
 void exportSVG(std::vector<std::reference_wrapper<Item>>& result, const Bin& bin, int idx = 0) {
 
 
@@ -500,6 +532,41 @@ TEST(GeometryAlgorithms, BottomLeftStressTest) {
     }
 }
 
+TEST(GeometryAlgorithms, convexHull) {
+    using namespace libnest2d;
+
+    ClipperLib::Path poly = PRINTER_PART_POLYGONS[0];
+
+    auto chull = sl::convexHull(poly);
+    
+    ASSERT_EQ(chull.size(), poly.size());
+}
+
+
+TEST(GeometryAlgorithms, NestTest) {
+    std::vector<Item> input = prusaParts();
+
+    PackGroup result = libnest2d::nest(input,
+                                       Box(250000000, 210000000),
+                                       [](unsigned cnt) {
+                                           std::cout
+                                               << "parts left: " << cnt
+                                               << std::endl;
+                                       });
+
+    ASSERT_LE(result.size(), 2);
+
+    int partsum = std::accumulate(result.begin(),
+                                  result.end(),
+                                  0,
+                                  [](int s,
+                                     const decltype(result)::value_type &bin) {
+                                      return s += bin.size();
+                                  });
+    
+    ASSERT_EQ(input.size(), partsum);
+}
+
 namespace {
 
 struct ItemPair {
@@ -713,7 +780,7 @@ void testNfp(const std::vector<ItemPair>& testdata) {
 
     auto& exportfun = exportSVG<SCALE, Box>;
 
-    auto onetest = [&](Item& orbiter, Item& stationary, unsigned testidx){
+    auto onetest = [&](Item& orbiter, Item& stationary, unsigned /*testidx*/){
         testcase++;
 
         orbiter.translate({210*SCALE, 0});
@@ -820,7 +887,7 @@ TEST(GeometryAlgorithms, mergePileWithPolygon) {
     rect2.translate({10, 0});
     rect3.translate({25, 0});
 
-    shapelike::Shapes<PolygonImpl> pile;
+    TMultiShape<PolygonImpl> pile;
     pile.push_back(rect1.transformedShape());
     pile.push_back(rect2.transformedShape());
 
@@ -833,6 +900,126 @@ TEST(GeometryAlgorithms, mergePileWithPolygon) {
     ASSERT_EQ(shapelike::area(result.front()), ref.area());
 }
 
+namespace {
+
+long double refMinAreaBox(const PolygonImpl& p) {    
+    
+    auto it = sl::cbegin(p), itx = std::next(it);
+    
+    long double min_area = std::numeric_limits<long double>::max();
+    
+ 
+    auto update_min = [&min_area, &it, &itx, &p]() {
+        Segment s(*it, *itx);
+        
+        PolygonImpl rotated = p;
+        sl::rotate(rotated, -s.angleToXaxis());
+        auto bb = sl::boundingBox(rotated);
+        auto area = cast<long double>(sl::area(bb));
+        if(min_area > area) min_area = area;
+    };
+    
+    while(itx != sl::cend(p)) {
+        update_min();
+        ++it; ++itx;
+    }
+    
+    it = std::prev(sl::cend(p)); itx = sl::cbegin(p);
+    update_min();
+    
+    return min_area;
+}
+
+template<class T> struct BoostGCD { 
+    T operator()(const T &a, const T &b) { return boost::gcd(a, b); }
+};
+
+using Unit = int64_t;
+using Ratio = boost::rational<boost::multiprecision::int128_t>;// Rational<boost::multiprecision::int256_t>;
+
+//double gteMinAreaBox(const PolygonImpl& p) {    
+    
+//    using GteCoord = ClipperLib::cInt;
+//    using GtePoint = gte::Vector2<GteCoord>;
+ 
+//    gte::MinimumAreaBox2<GteCoord, Ratio> mb;
+    
+//    std::vector<GtePoint> points; 
+//    points.reserve(p.Contour.size());
+    
+//    for(auto& pt : p.Contour) points.emplace_back(GtePoint{GteCoord(pt.X), GteCoord(pt.Y)});
+    
+//    mb(int(points.size()), points.data(), 0, nullptr, true);
+    
+//    auto min_area = double(mb.GetArea());
+    
+//    return min_area;
+//}
+
+}
+
+TEST(RotatingCalipers, MinAreaBBCClk) {
+//    PolygonImpl poly({{-50, 30}, {-50, -50}, {50, -50}, {50, 50}, {-40, 50}});
+    
+//    PolygonImpl poly({{-50, 0}, {50, 0}, {0, 100}});
+    
+    auto u = [](ClipperLib::cInt n) { return n*1000000; };
+    PolygonImpl poly({ {u(0), u(0)}, {u(4), u(1)}, {u(2), u(4)}});
+    
+    
+    long double arearef = refMinAreaBox(poly);
+    long double area = minAreaBoundingBox<PolygonImpl, Unit, Ratio>(poly).area();
+//    double gtearea = gteMinAreaBox(poly);
+    
+    ASSERT_LE(std::abs(area - arearef), 500e6 );
+//    ASSERT_LE(std::abs(gtearea - arearef), 500 );
+//    ASSERT_DOUBLE_EQ(gtearea, arearef);
+}
+
+TEST(RotatingCalipers, AllPrusaMinBB) {
+    size_t idx = 0;
+    long double err_epsilon = 500e6l;
+    
+    for(ClipperLib::Path rinput : PRINTER_PART_POLYGONS) {
+//        ClipperLib::Path rinput = PRINTER_PART_POLYGONS[idx];
+//        rinput.pop_back();
+//        std::reverse(rinput.begin(), rinput.end());
+        
+//        PolygonImpl poly(removeCollinearPoints<PathImpl, PointImpl, Unit>(rinput, 1000000));
+        PolygonImpl poly(rinput);
+        
+        long double arearef = refMinAreaBox(poly);
+        auto bb = minAreaBoundingBox<PathImpl, Unit, Ratio>(rinput);
+        long double area = cast<long double>(bb.area());
+//        double area = gteMinAreaBox(poly);
+        
+        bool succ = std::abs(arearef - area) < err_epsilon;
+        std::cout << idx++ << " " << (succ? "ok" : "failed") << " ref: " 
+                  << arearef << " actual: " << area << std::endl;
+        
+        ASSERT_TRUE(succ);
+    }
+    
+    for(ClipperLib::Path rinput : STEGOSAUR_POLYGONS) {
+        rinput.pop_back();
+        std::reverse(rinput.begin(), rinput.end());
+        
+        PolygonImpl poly(removeCollinearPoints<PathImpl, PointImpl, Unit>(rinput, 1000000));
+        
+        
+        long double arearef = refMinAreaBox(poly);
+        auto bb = minAreaBoundingBox<PolygonImpl, Unit, Ratio>(poly);
+        long double area = cast<long double>(bb.area());
+//        double area = gteMinAreaBox(poly);
+        
+        bool succ = std::abs(arearef - area) < err_epsilon;
+        std::cout << idx++ << " " << (succ? "ok" : "failed") << " ref: " 
+                  << arearef << " actual: " << area << std::endl;
+        
+        ASSERT_TRUE(succ);
+    }
+}
+
 int main(int argc, char **argv) {
   ::testing::InitGoogleTest(&argc, argv);
   return RUN_ALL_TESTS();
diff --git a/src/libslic3r/CMakeLists.txt b/src/libslic3r/CMakeLists.txt
index 312a82c4c..38e663604 100644
--- a/src/libslic3r/CMakeLists.txt
+++ b/src/libslic3r/CMakeLists.txt
@@ -130,13 +130,10 @@ add_library(libslic3r STATIC
     Print.hpp
     PrintBase.cpp
     PrintBase.hpp
-    PrintExport.hpp
     PrintConfig.cpp
     PrintConfig.hpp
     PrintObject.cpp
     PrintRegion.cpp
-    Rasterizer/Rasterizer.hpp
-    Rasterizer/Rasterizer.cpp
     SLAPrint.cpp
     SLAPrint.hpp
     SLA/SLAAutoSupports.hpp
@@ -163,6 +160,8 @@ add_library(libslic3r STATIC
     MTUtils.hpp
     Zipper.hpp
     Zipper.cpp
+    MinAreaBoundingBox.hpp
+    MinAreaBoundingBox.cpp
     miniz_extension.hpp
     miniz_extension.cpp
     SLA/SLABoilerPlate.hpp
@@ -175,6 +174,10 @@ add_library(libslic3r STATIC
     SLA/SLARotfinder.cpp
     SLA/SLABoostAdapter.hpp
     SLA/SLASpatIndex.hpp
+    SLA/SLARaster.hpp
+    SLA/SLARaster.cpp
+    SLA/SLARasterWriter.hpp
+    SLA/SLARasterWriter.cpp
 )
 
 if (SLIC3R_PCH AND NOT SLIC3R_SYNTAXONLY)
diff --git a/src/libslic3r/Fill/FillRectilinear3.cpp b/src/libslic3r/Fill/FillRectilinear3.cpp
index 8a0b90ead..dab584298 100644
--- a/src/libslic3r/Fill/FillRectilinear3.cpp
+++ b/src/libslic3r/Fill/FillRectilinear3.cpp
@@ -15,7 +15,7 @@
 
 #include "FillRectilinear3.hpp"
 
- #define SLIC3R_DEBUG
+// #define SLIC3R_DEBUG
 
 // Make assert active if SLIC3R_DEBUG
 #ifdef SLIC3R_DEBUG
diff --git a/src/libslic3r/Format/3mf.cpp b/src/libslic3r/Format/3mf.cpp
index 38b34c462..4793586e3 100644
--- a/src/libslic3r/Format/3mf.cpp
+++ b/src/libslic3r/Format/3mf.cpp
@@ -1489,10 +1489,10 @@ namespace Slic3r {
             }
 
             // splits volume out of imported geometry
-            unsigned int triangles_count = volume_data.last_triangle_id - volume_data.first_triangle_id + 1;
-            ModelVolume* volume = object.add_volume(TriangleMesh());
-            stl_file& stl = volume->mesh.stl;
-            stl.stats.type = inmemory;
+			TriangleMesh triangle_mesh;
+            stl_file    &stl             = triangle_mesh.stl;
+			unsigned int triangles_count = volume_data.last_triangle_id - volume_data.first_triangle_id + 1;
+			stl.stats.type = inmemory;
             stl.stats.number_of_facets = (uint32_t)triangles_count;
             stl.stats.original_num_facets = (int)stl.stats.number_of_facets;
             stl_allocate(&stl);
@@ -1509,9 +1509,11 @@ namespace Slic3r {
                 }
             }
 
-            stl_get_size(&stl);
-            volume->mesh.repair();
-            volume->center_geometry();
+			stl_get_size(&stl);
+			triangle_mesh.repair();
+
+			ModelVolume* volume = object.add_volume(std::move(triangle_mesh));
+            volume->center_geometry_after_creation();
             volume->calculate_convex_hull();
 
             // apply volume's name and config data
@@ -1879,29 +1881,28 @@ namespace Slic3r {
             if (volume == nullptr)
                 continue;
 
+			if (!volume->mesh().repaired)
+				throw std::runtime_error("store_3mf() requires repair()");
+			if (!volume->mesh().has_shared_vertices())
+				throw std::runtime_error("store_3mf() requires shared vertices");
+
             volumes_offsets.insert(VolumeToOffsetsMap::value_type(volume, Offsets(vertices_count))).first;
 
-            if (!volume->mesh.repaired)
-                volume->mesh.repair();
-
-            stl_file& stl = volume->mesh.stl;
-            if (stl.v_shared == nullptr)
-                stl_generate_shared_vertices(&stl);
-
-            if (stl.stats.shared_vertices == 0)
+            const indexed_triangle_set &its = volume->mesh().its;
+            if (its.vertices.empty())
             {
                 add_error("Found invalid mesh");
                 return false;
             }
 
-            vertices_count += stl.stats.shared_vertices;
+            vertices_count += its.vertices.size();
 
             const Transform3d& matrix = volume->get_matrix();
 
-            for (int i = 0; i < stl.stats.shared_vertices; ++i)
+            for (size_t i = 0; i < its.vertices.size(); ++i)
             {
                 stream << "     <" << VERTEX_TAG << " ";
-                Vec3f v = (matrix * stl.v_shared[i].cast<double>()).cast<float>();
+                Vec3f v = (matrix * its.vertices[i].cast<double>()).cast<float>();
                 stream << "x=\"" << v(0) << "\" ";
                 stream << "y=\"" << v(1) << "\" ";
                 stream << "z=\"" << v(2) << "\" />\n";
@@ -1920,19 +1921,19 @@ namespace Slic3r {
             VolumeToOffsetsMap::iterator volume_it = volumes_offsets.find(volume);
             assert(volume_it != volumes_offsets.end());
 
-            stl_file& stl = volume->mesh.stl;
+            const indexed_triangle_set &its = volume->mesh().its;
 
             // updates triangle offsets
             volume_it->second.first_triangle_id = triangles_count;
-            triangles_count += stl.stats.number_of_facets;
+            triangles_count += its.indices.size();
             volume_it->second.last_triangle_id = triangles_count - 1;
 
-            for (uint32_t i = 0; i < stl.stats.number_of_facets; ++i)
+            for (size_t i = 0; i < its.indices.size(); ++ i)
             {
                 stream << "     <" << TRIANGLE_TAG << " ";
                 for (int j = 0; j < 3; ++j)
                 {
-                    stream << "v" << j + 1 << "=\"" << stl.v_indices[i].vertex[j] + volume_it->second.first_vertex_id << "\" ";
+                    stream << "v" << j + 1 << "=\"" << its.indices[i][j] + volume_it->second.first_vertex_id << "\" ";
                 }
                 stream << "/>\n";
             }
diff --git a/src/libslic3r/Format/AMF.cpp b/src/libslic3r/Format/AMF.cpp
index d26b5f3ed..a33d21c9f 100644
--- a/src/libslic3r/Format/AMF.cpp
+++ b/src/libslic3r/Format/AMF.cpp
@@ -522,7 +522,8 @@ void AMFParserContext::endElement(const char * /* name */)
     case NODE_TYPE_VOLUME:
     {
 		assert(m_object && m_volume);
-        stl_file &stl = m_volume->mesh.stl;
+		TriangleMesh  mesh;
+        stl_file	 &stl = mesh.stl;
         stl.stats.type = inmemory;
         stl.stats.number_of_facets = int(m_volume_facets.size() / 3);
         stl.stats.original_num_facets = stl.stats.number_of_facets;
@@ -533,8 +534,9 @@ void AMFParserContext::endElement(const char * /* name */)
                 memcpy(facet.vertex[v].data(), &m_object_vertices[m_volume_facets[i ++] * 3], 3 * sizeof(float));
         }
         stl_get_size(&stl);
-        m_volume->mesh.repair();
-        m_volume->center_geometry();
+        mesh.repair();
+		m_volume->set_mesh(std::move(mesh));
+        m_volume->center_geometry_after_creation();
         m_volume->calculate_convex_hull();
         m_volume_facets.clear();
         m_volume = nullptr;
@@ -923,23 +925,23 @@ bool store_amf(const char *path, Model *model, const DynamicPrintConfig *config)
         int              num_vertices = 0;
         for (ModelVolume *volume : object->volumes) {
             vertices_offsets.push_back(num_vertices);
-            if (! volume->mesh.repaired) 
+            if (! volume->mesh().repaired)
                 throw std::runtime_error("store_amf() requires repair()");
-            auto &stl = volume->mesh.stl;
-            if (stl.v_shared == nullptr)
-                stl_generate_shared_vertices(&stl);
+			if (! volume->mesh().has_shared_vertices())
+				throw std::runtime_error("store_amf() requires shared vertices");
+            const indexed_triangle_set &its = volume->mesh().its;
             const Transform3d& matrix = volume->get_matrix();
-            for (size_t i = 0; i < stl.stats.shared_vertices; ++i) {
+            for (size_t i = 0; i < its.vertices.size(); ++i) {
                 stream << "         <vertex>\n";
                 stream << "           <coordinates>\n";
-                Vec3f v = (matrix * stl.v_shared[i].cast<double>()).cast<float>();
+                Vec3f v = (matrix * its.vertices[i].cast<double>()).cast<float>();
                 stream << "             <x>" << v(0) << "</x>\n";
                 stream << "             <y>" << v(1) << "</y>\n";
                 stream << "             <z>" << v(2) << "</z>\n";
                 stream << "           </coordinates>\n";
                 stream << "         </vertex>\n";
             }
-            num_vertices += stl.stats.shared_vertices;
+            num_vertices += its.vertices.size();
         }
         stream << "      </vertices>\n";
         for (size_t i_volume = 0; i_volume < object->volumes.size(); ++i_volume) {
@@ -956,10 +958,11 @@ bool store_amf(const char *path, Model *model, const DynamicPrintConfig *config)
             if (volume->is_modifier())
                 stream << "        <metadata type=\"slic3r.modifier\">1</metadata>\n";
             stream << "        <metadata type=\"slic3r.volume_type\">" << ModelVolume::type_to_string(volume->type()) << "</metadata>\n";
-            for (int i = 0; i < (int)volume->mesh.stl.stats.number_of_facets; ++i) {
+			const indexed_triangle_set &its = volume->mesh().its;
+            for (size_t i = 0; i < (int)its.indices.size(); ++i) {
                 stream << "        <triangle>\n";
                 for (int j = 0; j < 3; ++j)
-                stream << "          <v" << j + 1 << ">" << volume->mesh.stl.v_indices[i].vertex[j] + vertices_offset << "</v" << j + 1 << ">\n";
+                stream << "          <v" << j + 1 << ">" << its.indices[i][j] + vertices_offset << "</v" << j + 1 << ">\n";
                 stream << "        </triangle>\n";
             }
             stream << "      </volume>\n";
diff --git a/src/libslic3r/Format/PRUS.cpp b/src/libslic3r/Format/PRUS.cpp
index 502cac6e9..03ea71a83 100644
--- a/src/libslic3r/Format/PRUS.cpp
+++ b/src/libslic3r/Format/PRUS.cpp
@@ -161,16 +161,15 @@ static void extract_model_from_archive(
         else {
             // Header has been extracted. Now read the faces.
             stl_file &stl = mesh.stl;
-            stl.error = 0;
             stl.stats.type = inmemory;
             stl.stats.number_of_facets = header.nTriangles;
             stl.stats.original_num_facets = header.nTriangles;
             stl_allocate(&stl);
             if (header.nTriangles > 0 && data.size() == 50 * header.nTriangles + sizeof(StlHeader)) {
-                memcpy((char*)stl.facet_start, data.data() + sizeof(StlHeader), 50 * header.nTriangles);
+                memcpy((char*)stl.facet_start.data(), data.data() + sizeof(StlHeader), 50 * header.nTriangles);
                 if (sizeof(stl_facet) > SIZEOF_STL_FACET) {
                     // The stl.facet_start is not packed tightly. Unpack the array of stl_facets.
-                    unsigned char *data = (unsigned char*)stl.facet_start;
+                    unsigned char *data = (unsigned char*)stl.facet_start.data();
                     for (size_t i = header.nTriangles - 1; i > 0; -- i)
                         memmove(data + i * sizeof(stl_facet), data + i * SIZEOF_STL_FACET, SIZEOF_STL_FACET);
                 }
@@ -257,7 +256,7 @@ static void extract_model_from_archive(
             stl.stats.number_of_facets = (uint32_t)facets.size();
             stl.stats.original_num_facets = (int)facets.size();
             stl_allocate(&stl);
-            memcpy((void*)stl.facet_start, facets.data(), facets.size() * 50);
+            memcpy((void*)stl.facet_start.data(), facets.data(), facets.size() * 50);
             stl_get_size(&stl);
             mesh.repair();
             // Add a mesh to a model.
diff --git a/src/libslic3r/Format/STL.cpp b/src/libslic3r/Format/STL.cpp
index b00623d1d..932906fe0 100644
--- a/src/libslic3r/Format/STL.cpp
+++ b/src/libslic3r/Format/STL.cpp
@@ -17,8 +17,7 @@ namespace Slic3r {
 bool load_stl(const char *path, Model *model, const char *object_name_in)
 {
     TriangleMesh mesh;
-    mesh.ReadSTLFile(path);
-    if (mesh.stl.error) {
+    if (! mesh.ReadSTLFile(path)) {
 //    die "Failed to open $file\n" if !-e $path;
         return false;
     }
diff --git a/src/libslic3r/Int128.hpp b/src/libslic3r/Int128.hpp
index 56dc5f461..8dc9e012d 100644
--- a/src/libslic3r/Int128.hpp
+++ b/src/libslic3r/Int128.hpp
@@ -37,6 +37,8 @@
 *                                                                              *
 *******************************************************************************/
 
+#ifndef SLIC3R_INT128_HPP
+#define SLIC3R_INT128_HPP
 // #define SLIC3R_DEBUG
 
 // Make assert active if SLIC3R_DEBUG
@@ -48,6 +50,8 @@
 #endif
 
 #include <cassert>
+#include <cstdint>
+#include <cmath>
 
 #if ! defined(_MSC_VER) && defined(__SIZEOF_INT128__)
 	#define HAS_INTRINSIC_128_TYPE
@@ -293,3 +297,5 @@ public:
 		return sign_determinant_2x2(p1, q1, p2, q2) * invert;
 	}
 };
+
+#endif // SLIC3R_INT128_HPP
diff --git a/src/libslic3r/MTUtils.hpp b/src/libslic3r/MTUtils.hpp
index ee70f535d..7bfa39ec2 100644
--- a/src/libslic3r/MTUtils.hpp
+++ b/src/libslic3r/MTUtils.hpp
@@ -185,6 +185,14 @@ public:
     inline bool empty() const { return size() == 0; }
 };
 
+template<class C> bool all_of(const C &container) {
+    return std::all_of(container.begin(),
+                       container.end(),
+                       [](const typename C::value_type &v) {
+                           return static_cast<bool>(v);
+                       });
+}
+
 template<class T>
 struct remove_cvref
 {
diff --git a/src/libslic3r/MinAreaBoundingBox.cpp b/src/libslic3r/MinAreaBoundingBox.cpp
new file mode 100644
index 000000000..6fc1b3327
--- /dev/null
+++ b/src/libslic3r/MinAreaBoundingBox.cpp
@@ -0,0 +1,142 @@
+#include "MinAreaBoundingBox.hpp"
+
+#include <libslic3r/ExPolygon.hpp>
+#include <boost/rational.hpp>
+
+#include <libslic3r/Int128.hpp>
+
+#if !defined(HAS_INTRINSIC_128_TYPE) || defined(__APPLE__)
+#include <boost/multiprecision/integer.hpp>
+#endif
+
+#include <libnest2d/geometry_traits.hpp>
+#include <libnest2d/utils/rotcalipers.hpp>
+
+namespace libnest2d {
+
+template<> struct PointType<Slic3r::Points>      { using Type = Slic3r::Point; };
+template<> struct CoordType<Slic3r::Point>       { using Type = coord_t; };
+template<> struct ShapeTag<Slic3r::ExPolygon>    { using Type = PolygonTag; };
+template<> struct ShapeTag<Slic3r::Polygon>      { using Type = PolygonTag; };
+template<> struct ShapeTag<Slic3r::Points>       { using Type = PathTag; };
+template<> struct ShapeTag<Slic3r::Point>        { using Type = PointTag; };
+template<> struct ContourType<Slic3r::ExPolygon> { using Type = Slic3r::Points; };
+template<> struct ContourType<Slic3r::Polygon>   { using Type = Slic3r::Points; };
+
+namespace pointlike {
+
+template<> inline coord_t x(const Slic3r::Point& p) { return p.x(); }
+template<> inline coord_t y(const Slic3r::Point& p) { return p.y(); }
+template<> inline coord_t& x(Slic3r::Point& p)      { return p.x(); }
+template<> inline coord_t& y(Slic3r::Point& p)      { return p.y(); }
+
+} // pointlike
+
+namespace shapelike {
+template<> inline Slic3r::Points& contour(Slic3r::ExPolygon& sh) { return sh.contour.points; }
+template<> inline const Slic3r::Points& contour(const Slic3r::ExPolygon& sh) { return sh.contour.points; }
+template<> inline Slic3r::Points& contour(Slic3r::Polygon& sh) { return sh.points; }
+template<> inline const Slic3r::Points& contour(const Slic3r::Polygon& sh) { return sh.points; }
+
+template<> Slic3r::Points::iterator begin(Slic3r::Points& pts, const PathTag&) { return pts.begin();}
+template<> Slic3r::Points::const_iterator cbegin(const Slic3r::Points& pts, const PathTag&) { return pts.begin(); }
+template<> Slic3r::Points::iterator end(Slic3r::Points& pts, const PathTag&) { return pts.end();}
+template<> Slic3r::Points::const_iterator cend(const Slic3r::Points& pts, const PathTag&) { return pts.cend(); }
+
+template<> inline Slic3r::ExPolygon create<Slic3r::ExPolygon>(Slic3r::Points&& contour)
+{
+    Slic3r::ExPolygon expoly; expoly.contour.points.swap(contour);
+    return expoly;
+}
+
+template<> inline Slic3r::Polygon create<Slic3r::Polygon>(Slic3r::Points&& contour)
+{
+    Slic3r::Polygon poly; poly.points.swap(contour);
+    return poly;
+}
+
+} // shapelike
+} // libnest2d
+
+namespace Slic3r {
+
+// Used as compute type.
+using Unit = int64_t;
+
+#if !defined(HAS_INTRINSIC_128_TYPE) || defined(__APPLE__)
+using Rational = boost::rational<boost::multiprecision::int128_t>;
+#else
+using Rational = boost::rational<__int128>;
+#endif
+
+MinAreaBoundigBox::MinAreaBoundigBox(const Polygon &p, PolygonLevel pc)
+{
+    const Polygon& chull = pc == pcConvex ? p : libnest2d::sl::convexHull(p);
+    
+    libnest2d::RotatedBox<Point, Unit> box = 
+            libnest2d::minAreaBoundingBox<Polygon, Unit, Rational>(chull);
+    
+    m_right = box.right_extent();
+    m_bottom = box.bottom_extent();
+    m_axis = box.axis();
+}
+
+MinAreaBoundigBox::MinAreaBoundigBox(const ExPolygon &p, PolygonLevel pc)
+{
+    const ExPolygon& chull = pc == pcConvex ? p : libnest2d::sl::convexHull(p);
+    
+    libnest2d::RotatedBox<Point, Unit> box = 
+            libnest2d::minAreaBoundingBox<ExPolygon, Unit, Rational>(chull);
+    
+    m_right = box.right_extent();
+    m_bottom = box.bottom_extent();
+    m_axis = box.axis();
+}
+
+MinAreaBoundigBox::MinAreaBoundigBox(const Points &pts, PolygonLevel pc)
+{
+    const Points& chull = pc == pcConvex ? pts : libnest2d::sl::convexHull(pts);
+    
+    libnest2d::RotatedBox<Point, Unit> box = 
+            libnest2d::minAreaBoundingBox<Points, Unit, Rational>(chull);
+    
+    m_right = box.right_extent();
+    m_bottom = box.bottom_extent();
+    m_axis = box.axis();
+}
+
+double MinAreaBoundigBox::angle_to_X() const
+{
+    double ret = std::atan2(m_axis.y(), m_axis.x());
+    auto s = std::signbit(ret);
+    if(s) ret += 2 * PI;
+    return -ret;
+}
+
+long double MinAreaBoundigBox::width() const
+{
+    return std::abs(m_bottom) / std::sqrt(libnest2d::pl::magnsq<Point, long double>(m_axis));
+}
+
+long double MinAreaBoundigBox::height() const
+{
+    return std::abs(m_right) / std::sqrt(libnest2d::pl::magnsq<Point, long double>(m_axis));
+}
+
+long double MinAreaBoundigBox::area() const
+{
+    long double asq = libnest2d::pl::magnsq<Point, long double>(m_axis);
+    return m_bottom * m_right / asq;   
+}
+
+void remove_collinear_points(Polygon &p)
+{
+    p = libnest2d::removeCollinearPoints<Polygon>(p, Unit(0));
+}
+
+void remove_collinear_points(ExPolygon &p)
+{
+    p = libnest2d::removeCollinearPoints<ExPolygon>(p, Unit(0));
+}
+
+}
diff --git a/src/libslic3r/MinAreaBoundingBox.hpp b/src/libslic3r/MinAreaBoundingBox.hpp
new file mode 100644
index 000000000..30d0e9799
--- /dev/null
+++ b/src/libslic3r/MinAreaBoundingBox.hpp
@@ -0,0 +1,59 @@
+#ifndef MINAREABOUNDINGBOX_HPP
+#define MINAREABOUNDINGBOX_HPP
+
+#include "libslic3r/Point.hpp"
+
+namespace Slic3r {
+
+class Polygon;
+class ExPolygon;
+
+void remove_collinear_points(Polygon& p);
+void remove_collinear_points(ExPolygon& p);
+
+/// A class that holds a rotated bounding box. If instantiated with a polygon
+/// type it will hold the minimum area bounding box for the given polygon.
+/// If the input polygon is convex, the complexity is linear to the number of 
+/// points. Otherwise a convex hull of O(n*log(n)) has to be performed.
+class MinAreaBoundigBox {
+    Point m_axis;    
+    long double m_bottom = 0.0l, m_right = 0.0l;
+public:
+    
+    // Polygons can be convex or simple (convex or concave with possible holes)
+    enum PolygonLevel {
+        pcConvex, pcSimple
+    };
+   
+    // Constructors with various types of geometry data used in Slic3r.
+    // If the convexity is known apriory, pcConvex can be used to skip 
+    // convex hull calculation. It is very important that the input polygons
+    // do NOT have any collinear points (except for the first and the last 
+    // vertex being the same -- meaning a closed polygon for boost)
+    // To make sure this constraint is satisfied, you can call 
+    // remove_collinear_points on the input polygon before handing over here)
+    explicit MinAreaBoundigBox(const Polygon&, PolygonLevel = pcSimple);
+    explicit MinAreaBoundigBox(const ExPolygon&, PolygonLevel = pcSimple);
+    explicit MinAreaBoundigBox(const Points&, PolygonLevel = pcSimple);
+    
+    // Returns the angle in radians needed for the box to be aligned with the 
+    // X axis. Rotate the polygon by this angle and it will be aligned.
+    double angle_to_X()  const;
+    
+    // The box width
+    long double width()  const;
+    
+    // The box height
+    long double height() const;
+    
+    // The box area
+    long double area()   const;
+    
+    // The axis of the rotated box. If the angle_to_X is not sufficiently 
+    // precise, use this unnormalized direction vector.
+    const Point& axis()  const { return m_axis; }
+};
+
+}
+
+#endif // MINAREABOUNDINGBOX_HPP
diff --git a/src/libslic3r/Model.cpp b/src/libslic3r/Model.cpp
index 3b1bd5df2..8e879a3e6 100644
--- a/src/libslic3r/Model.cpp
+++ b/src/libslic3r/Model.cpp
@@ -160,12 +160,6 @@ Model Model::read_from_archive(const std::string &input_file, DynamicPrintConfig
     return model;
 }
 
-void Model::repair()
-{
-    for (ModelObject *o : this->objects)
-        o->repair();
-}
-
 ModelObject* Model::add_object()
 {
     this->objects.emplace_back(new ModelObject(this));
@@ -472,7 +466,7 @@ bool Model::looks_like_multipart_object() const
         if (obj->volumes.size() > 1 || obj->config.keys().size() > 1)
             return false;
         for (const ModelVolume *vol : obj->volumes) {
-            double zmin_this = vol->mesh.bounding_box().min(2);
+            double zmin_this = vol->mesh().bounding_box().min(2);
             if (zmin == std::numeric_limits<double>::max())
                 zmin = zmin_this;
             else if (std::abs(zmin - zmin_this) > EPSILON)
@@ -679,7 +673,7 @@ ModelVolume* ModelObject::add_volume(const TriangleMesh &mesh)
 {
     ModelVolume* v = new ModelVolume(this, mesh);
     this->volumes.push_back(v);
-    v->center_geometry();
+    v->center_geometry_after_creation();
     this->invalidate_bounding_box();
     return v;
 }
@@ -688,7 +682,7 @@ ModelVolume* ModelObject::add_volume(TriangleMesh &&mesh)
 {
     ModelVolume* v = new ModelVolume(this, std::move(mesh));
     this->volumes.push_back(v);
-    v->center_geometry();
+    v->center_geometry_after_creation();
     this->invalidate_bounding_box();
     return v;
 }
@@ -697,8 +691,9 @@ ModelVolume* ModelObject::add_volume(const ModelVolume &other)
 {
     ModelVolume* v = new ModelVolume(this, other);
     this->volumes.push_back(v);
-    v->center_geometry();
-    this->invalidate_bounding_box();
+	// The volume should already be centered at this point of time when copying shared pointers of the triangle mesh and convex hull.
+//	v->center_geometry_after_creation();
+//    this->invalidate_bounding_box();
     return v;
 }
 
@@ -706,7 +701,7 @@ ModelVolume* ModelObject::add_volume(const ModelVolume &other, TriangleMesh &&me
 {
     ModelVolume* v = new ModelVolume(this, other, std::move(mesh));
     this->volumes.push_back(v);
-    v->center_geometry();
+    v->center_geometry_after_creation();
     this->invalidate_bounding_box();
     return v;
 }
@@ -827,7 +822,7 @@ TriangleMesh ModelObject::raw_mesh() const
     for (const ModelVolume *v : this->volumes)
         if (v->is_model_part())
         {
-            TriangleMesh vol_mesh(v->mesh);
+            TriangleMesh vol_mesh(v->mesh());
             vol_mesh.transform(v->get_matrix());
             mesh.merge(vol_mesh);
         }
@@ -840,7 +835,7 @@ TriangleMesh ModelObject::full_raw_mesh() const
     TriangleMesh mesh;
     for (const ModelVolume *v : this->volumes)
     {
-        TriangleMesh vol_mesh(v->mesh);
+        TriangleMesh vol_mesh(v->mesh());
         vol_mesh.transform(v->get_matrix());
         mesh.merge(vol_mesh);
     }
@@ -854,7 +849,7 @@ const BoundingBoxf3& ModelObject::raw_mesh_bounding_box() const
         m_raw_mesh_bounding_box.reset();
         for (const ModelVolume *v : this->volumes)
             if (v->is_model_part())
-                m_raw_mesh_bounding_box.merge(v->mesh.transformed_bounding_box(v->get_matrix()));
+                m_raw_mesh_bounding_box.merge(v->mesh().transformed_bounding_box(v->get_matrix()));
     }
     return m_raw_mesh_bounding_box;
 }
@@ -863,7 +858,7 @@ BoundingBoxf3 ModelObject::full_raw_mesh_bounding_box() const
 {
 	BoundingBoxf3 bb;
 	for (const ModelVolume *v : this->volumes)
-		bb.merge(v->mesh.transformed_bounding_box(v->get_matrix()));
+		bb.merge(v->mesh().transformed_bounding_box(v->get_matrix()));
 	return bb;
 }
 
@@ -881,7 +876,7 @@ const BoundingBoxf3& ModelObject::raw_bounding_box() const
         for (const ModelVolume *v : this->volumes)
         {
             if (v->is_model_part())
-                m_raw_bounding_box.merge(v->mesh.transformed_bounding_box(inst_matrix * v->get_matrix()));
+                m_raw_bounding_box.merge(v->mesh().transformed_bounding_box(inst_matrix * v->get_matrix()));
         }
     }
 	return m_raw_bounding_box;
@@ -895,7 +890,7 @@ BoundingBoxf3 ModelObject::instance_bounding_box(size_t instance_idx, bool dont_
     for (ModelVolume *v : this->volumes)
     {
         if (v->is_model_part())
-            bb.merge(v->mesh.transformed_bounding_box(inst_matrix * v->get_matrix()));
+            bb.merge(v->mesh().transformed_bounding_box(inst_matrix * v->get_matrix()));
     }
     return bb;
 }
@@ -908,21 +903,20 @@ Polygon ModelObject::convex_hull_2d(const Transform3d &trafo_instance) const
     Points pts;
     for (const ModelVolume *v : this->volumes)
         if (v->is_model_part()) {
-            const stl_file &stl = v->mesh.stl;
             Transform3d trafo = trafo_instance * v->get_matrix();
-            if (stl.v_shared == nullptr) {
+			const indexed_triangle_set &its = v->mesh().its;
+			if (its.vertices.empty()) {
                 // Using the STL faces.
-                for (unsigned int i = 0; i < stl.stats.number_of_facets; ++ i) {
-                    const stl_facet &facet = stl.facet_start[i];
+				const stl_file& stl = v->mesh().stl;
+				for (const stl_facet &facet : stl.facet_start)
                     for (size_t j = 0; j < 3; ++ j) {
                         Vec3d p = trafo * facet.vertex[j].cast<double>();
                         pts.emplace_back(coord_t(scale_(p.x())), coord_t(scale_(p.y())));
                     }
-                }
             } else {
                 // Using the shared vertices should be a bit quicker than using the STL faces.
-                for (int i = 0; i < stl.stats.shared_vertices; ++ i) {           
-                    Vec3d p = trafo * stl.v_shared[i].cast<double>();
+                for (size_t i = 0; i < its.vertices.size(); ++ i) {
+                    Vec3d p = trafo * its.vertices[i].cast<double>();
                     pts.emplace_back(coord_t(scale_(p.x())), coord_t(scale_(p.y())));
                 }
             }
@@ -1039,6 +1033,7 @@ void ModelObject::mirror(Axis axis)
     this->invalidate_bounding_box();
 }
 
+// This method could only be called before the meshes of this ModelVolumes are not shared!
 void ModelObject::scale_mesh(const Vec3d &versor)
 {
     for (ModelVolume *v : this->volumes)
@@ -1062,14 +1057,14 @@ size_t ModelObject::facets_count() const
     size_t num = 0;
     for (const ModelVolume *v : this->volumes)
         if (v->is_model_part())
-            num += v->mesh.stl.stats.number_of_facets;
+            num += v->mesh().stl.stats.number_of_facets;
     return num;
 }
 
 bool ModelObject::needed_repair() const
 {
     for (const ModelVolume *v : this->volumes)
-        if (v->is_model_part() && v->mesh.needed_repair())
+        if (v->is_model_part() && v->mesh().needed_repair())
             return true;
     return false;
 }
@@ -1135,11 +1130,12 @@ ModelObjectPtrs ModelObject::cut(size_t instance, coordf_t z, bool keep_upper, b
 
             // Transform the mesh by the combined transformation matrix.
             // Flip the triangles in case the composite transformation is left handed.
-            volume->mesh.transform(instance_matrix * volume_matrix, true);
+			TriangleMesh mesh(volume->mesh());
+			mesh.transform(instance_matrix * volume_matrix, true);
+			volume->reset_mesh();
 
             // Perform cut
-            volume->mesh.require_shared_vertices(); // TriangleMeshSlicer needs this
-            TriangleMeshSlicer tms(&volume->mesh);
+            TriangleMeshSlicer tms(&mesh);
             tms.cut(float(z), &upper_mesh, &lower_mesh);
 
             // Reset volume transformation except for offset
@@ -1158,14 +1154,14 @@ ModelObjectPtrs ModelObject::cut(size_t instance, coordf_t z, bool keep_upper, b
 
             if (keep_upper && upper_mesh.facets_count() > 0) {
                 ModelVolume* vol = upper->add_volume(upper_mesh);
-                vol->name = volume->name;
-                vol->config         = volume->config;
+                vol->name	= volume->name;
+                vol->config = volume->config;
                 vol->set_material(volume->material_id(), *volume->material());
             }
             if (keep_lower && lower_mesh.facets_count() > 0) {
                 ModelVolume* vol = lower->add_volume(lower_mesh);
-                vol->name = volume->name;
-                vol->config         = volume->config;
+                vol->name	= volume->name;
+                vol->config = volume->config;
                 vol->set_material(volume->material_id(), *volume->material());
 
                 // Compute the lower part instances' bounding boxes to figure out where to place
@@ -1233,7 +1229,7 @@ void ModelObject::split(ModelObjectPtrs* new_objects)
     }
     
     ModelVolume* volume = this->volumes.front();
-    TriangleMeshPtrs meshptrs = volume->mesh.split();
+    TriangleMeshPtrs meshptrs = volume->mesh().split();
     for (TriangleMesh *mesh : meshptrs) {
         mesh->repair();
         
@@ -1260,12 +1256,6 @@ void ModelObject::split(ModelObjectPtrs* new_objects)
     return;
 }
 
-void ModelObject::repair()
-{
-    for (ModelVolume *v : this->volumes)
-        v->mesh.repair();
-}
-
 // Support for non-uniform scaling of instances. If an instance is rotated by angles, which are not multiples of ninety degrees,
 // then the scaling in world coordinate system is not representable by the Geometry::Transformation structure.
 // This situation is solved by baking in the instance transformation into the mesh vertices.
@@ -1295,8 +1285,8 @@ void ModelObject::bake_xy_rotation_into_meshes(size_t instance_idx)
 
     // Adjust the meshes.
     // Transformation to be applied to the meshes.
-    Eigen::Matrix3d    mesh_trafo_3x3           = reference_trafo.get_matrix(true, false, uniform_scaling, ! has_mirrorring).matrix().block<3, 3>(0, 0);
-	Transform3d volume_offset_correction = this->instances[instance_idx]->get_transformation().get_matrix().inverse() * reference_trafo.get_matrix();
+    Eigen::Matrix3d mesh_trafo_3x3           = reference_trafo.get_matrix(true, false, uniform_scaling, ! has_mirrorring).matrix().block<3, 3>(0, 0);
+	Transform3d     volume_offset_correction = this->instances[instance_idx]->get_transformation().get_matrix().inverse() * reference_trafo.get_matrix();
     for (ModelVolume *model_volume : this->volumes) {
         const Geometry::Transformation volume_trafo = model_volume->get_transformation();
         bool   volume_left_handed        = volume_trafo.is_left_handed();
@@ -1306,7 +1296,8 @@ void ModelObject::bake_xy_rotation_into_meshes(size_t instance_idx)
         double volume_new_scaling_factor = volume_uniform_scaling ? volume_trafo.get_scaling_factor().x() : 1.;
         // Transform the mesh.
 		Matrix3d volume_trafo_3x3 = volume_trafo.get_matrix(true, false, volume_uniform_scaling, !volume_has_mirrorring).matrix().block<3, 3>(0, 0);
-		model_volume->transform_mesh(mesh_trafo_3x3 * volume_trafo_3x3, left_handed != volume_left_handed);
+        // Following method creates a new shared_ptr<TriangleMesh>
+		model_volume->transform_this_mesh(mesh_trafo_3x3 * volume_trafo_3x3, left_handed != volume_left_handed);
         // Reset the rotation, scaling and mirroring.
         model_volume->set_rotation(Vec3d(0., 0., 0.));
         model_volume->set_scaling_factor(Vec3d(volume_new_scaling_factor, volume_new_scaling_factor, volume_new_scaling_factor));
@@ -1347,13 +1338,9 @@ double ModelObject::get_instance_min_z(size_t instance_idx) const
 
         Transform3d mv = mi * v->get_matrix();
         const TriangleMesh& hull = v->get_convex_hull();
-        for (uint32_t f = 0; f < hull.stl.stats.number_of_facets; ++f)
-        {
-            const stl_facet* facet = hull.stl.facet_start + f;
-            min_z = std::min(min_z, Vec3d::UnitZ().dot(mv * facet->vertex[0].cast<double>()));
-            min_z = std::min(min_z, Vec3d::UnitZ().dot(mv * facet->vertex[1].cast<double>()));
-            min_z = std::min(min_z, Vec3d::UnitZ().dot(mv * facet->vertex[2].cast<double>()));
-        }
+		for (const stl_facet &facet : hull.stl.facet_start)
+			for (int i = 0; i < 3; ++ i)
+				min_z = std::min(min_z, (mv * facet.vertex[i].cast<double>()).z());
     }
 
     return min_z + inst->get_offset(Z);
@@ -1452,7 +1439,7 @@ std::string ModelObject::get_export_filename() const
 stl_stats ModelObject::get_object_stl_stats() const
 {
     if (this->volumes.size() == 1)
-        return this->volumes[0]->mesh.stl.stats;
+        return this->volumes[0]->mesh().stl.stats;
 
     stl_stats full_stats;
     memset(&full_stats, 0, sizeof(stl_stats));
@@ -1463,7 +1450,7 @@ stl_stats ModelObject::get_object_stl_stats() const
         if (volume->id() == this->volumes[0]->id())
             continue;
 
-        const stl_stats& stats = volume->mesh.stl.stats;
+        const stl_stats& stats = volume->mesh().stl.stats;
 
         // initialize full_stats (for repaired errors)
         full_stats.degenerate_facets    += stats.degenerate_facets;
@@ -1531,30 +1518,30 @@ bool ModelVolume::is_splittable() const
 {
     // the call mesh.is_splittable() is expensive, so cache the value to calculate it only once
     if (m_is_splittable == -1)
-        m_is_splittable = (int)mesh.is_splittable();
+        m_is_splittable = (int)this->mesh().is_splittable();
 
     return m_is_splittable == 1;
 }
 
-void ModelVolume::center_geometry()
+void ModelVolume::center_geometry_after_creation()
 {
-    Vec3d shift = mesh.bounding_box().center();
+    Vec3d shift = this->mesh().bounding_box().center();
     if (!shift.isApprox(Vec3d::Zero()))
     {
-        mesh.translate(-(float)shift(0), -(float)shift(1), -(float)shift(2));
-        m_convex_hull.translate(-(float)shift(0), -(float)shift(1), -(float)shift(2));
+        m_mesh->translate(-(float)shift(0), -(float)shift(1), -(float)shift(2));
+        m_convex_hull->translate(-(float)shift(0), -(float)shift(1), -(float)shift(2));
         translate(shift);
     }
 }
 
 void ModelVolume::calculate_convex_hull()
 {
-    m_convex_hull = mesh.convex_hull_3d();
+    m_convex_hull = std::make_shared<TriangleMesh>(this->mesh().convex_hull_3d());
 }
 
 int ModelVolume::get_mesh_errors_count() const
 {
-    const stl_stats& stats = this->mesh.stl.stats;
+    const stl_stats& stats = this->mesh().stl.stats;
 
     return  stats.degenerate_facets + stats.edges_fixed     + stats.facets_removed +
             stats.facets_added      + stats.facets_reversed + stats.backwards_edges;
@@ -1562,7 +1549,7 @@ int ModelVolume::get_mesh_errors_count() const
 
 const TriangleMesh& ModelVolume::get_convex_hull() const
 {
-    return m_convex_hull;
+    return *m_convex_hull.get();
 }
 
 ModelVolumeType ModelVolume::type_from_string(const std::string &s)
@@ -1602,7 +1589,7 @@ std::string ModelVolume::type_to_string(const ModelVolumeType t)
 // This is useful to assign different materials to different volumes of an object.
 size_t ModelVolume::split(unsigned int max_extruders)
 {
-    TriangleMeshPtrs meshptrs = this->mesh.split();
+    TriangleMeshPtrs meshptrs = this->mesh().split();
     if (meshptrs.size() <= 1) {
         delete meshptrs.front();
         return 1;
@@ -1619,7 +1606,7 @@ size_t ModelVolume::split(unsigned int max_extruders)
         mesh->repair();
         if (idx == 0)
         {
-            this->mesh = std::move(*mesh);
+            this->set_mesh(std::move(*mesh));
             this->calculate_convex_hull();
             // Assign a new unique ID, so that a new GLVolume will be generated.
             this->set_new_unique_id();
@@ -1628,7 +1615,7 @@ size_t ModelVolume::split(unsigned int max_extruders)
             this->object->volumes.insert(this->object->volumes.begin() + (++ivolume), new ModelVolume(object, *this, std::move(*mesh)));
 
         this->object->volumes[ivolume]->set_offset(Vec3d::Zero());
-        this->object->volumes[ivolume]->center_geometry();
+        this->object->volumes[ivolume]->center_geometry_after_creation();
         this->object->volumes[ivolume]->translate(offset);
         this->object->volumes[ivolume]->name = name + "_" + std::to_string(idx + 1);
         this->object->volumes[ivolume]->config.set_deserialize("extruder", Model::get_auto_extruder_id_as_string(max_extruders));
@@ -1694,24 +1681,33 @@ void ModelVolume::mirror(Axis axis)
     set_mirror(mirror);
 }
 
+// This method could only be called before the meshes of this ModelVolumes are not shared!
 void ModelVolume::scale_geometry(const Vec3d& versor)
 {
-    mesh.scale(versor);
-    m_convex_hull.scale(versor);
+    m_mesh->scale(versor);
+    m_convex_hull->scale(versor);
 }
 
-void ModelVolume::transform_mesh(const Transform3d &mesh_trafo, bool fix_left_handed)
+void ModelVolume::transform_this_mesh(const Transform3d &mesh_trafo, bool fix_left_handed)
 {
-    this->mesh.transform(mesh_trafo, fix_left_handed);
-    this->m_convex_hull.transform(mesh_trafo, fix_left_handed);
+	TriangleMesh mesh = this->mesh();
+	mesh.transform(mesh_trafo, fix_left_handed);
+	this->set_mesh(std::move(mesh));
+    TriangleMesh convex_hull = this->get_convex_hull();
+    convex_hull.transform(mesh_trafo, fix_left_handed);
+    this->m_convex_hull = std::make_shared<TriangleMesh>(std::move(convex_hull));
     // Let the rest of the application know that the geometry changed, so the meshes have to be reloaded.
     this->set_new_unique_id();
 }
 
-void ModelVolume::transform_mesh(const Matrix3d &matrix, bool fix_left_handed)
+void ModelVolume::transform_this_mesh(const Matrix3d &matrix, bool fix_left_handed)
 {
-	this->mesh.transform(matrix, fix_left_handed);
-	this->m_convex_hull.transform(matrix, fix_left_handed);
+	TriangleMesh mesh = this->mesh();
+	mesh.transform(matrix, fix_left_handed);
+	this->set_mesh(std::move(mesh));
+    TriangleMesh convex_hull = this->get_convex_hull();
+    convex_hull.transform(matrix, fix_left_handed);
+    this->m_convex_hull = std::make_shared<TriangleMesh>(std::move(convex_hull));
     // Let the rest of the application know that the geometry changed, so the meshes have to be reloaded.
     this->set_new_unique_id();
 }
diff --git a/src/libslic3r/Model.hpp b/src/libslic3r/Model.hpp
index 41bf5bd4b..0fd1140f0 100644
--- a/src/libslic3r/Model.hpp
+++ b/src/libslic3r/Model.hpp
@@ -7,7 +7,9 @@
 #include "Point.hpp"
 #include "TriangleMesh.hpp"
 #include "Slicing.hpp"
+
 #include <map>
+#include <memory>
 #include <string>
 #include <utility>
 #include <vector>
@@ -261,6 +263,7 @@ public:
     void rotate(double angle, const Vec3d& axis);
     void mirror(Axis axis);
 
+    // This method could only be called before the meshes of this ModelVolumes are not shared!
     void scale_mesh(const Vec3d& versor);
 
     size_t materials_count() const;
@@ -268,7 +271,6 @@ public:
     bool needed_repair() const;
     ModelObjectPtrs cut(size_t instance, coordf_t z, bool keep_upper = true, bool keep_lower = true, bool rotate_lower = false);    // Note: z is in world coordinates
     void split(ModelObjectPtrs* new_objects);
-    void repair();
     // Support for non-uniform scaling of instances. If an instance is rotated by angles, which are not multiples of ninety degrees,
     // then the scaling in world coordinate system is not representable by the Geometry::Transformation structure.
     // This situation is solved by baking in the instance transformation into the mesh vertices.
@@ -340,7 +342,12 @@ class ModelVolume : public ModelBase
 public:
     std::string         name;
     // The triangular model.
-    TriangleMesh        mesh;
+    const TriangleMesh& mesh() const { return *m_mesh.get(); }
+    void                set_mesh(const TriangleMesh &mesh) { m_mesh = std::make_shared<TriangleMesh>(mesh); }
+    void                set_mesh(TriangleMesh &&mesh) { m_mesh = std::make_shared<TriangleMesh>(std::move(mesh)); }
+    void                set_mesh(std::shared_ptr<TriangleMesh> &mesh) { m_mesh = mesh; }
+    void                set_mesh(std::unique_ptr<TriangleMesh> &&mesh) { m_mesh = std::move(mesh); }
+	void				reset_mesh() { m_mesh = std::make_shared<TriangleMesh>(); }
     // Configuration parameters specific to an object model geometry or a modifier volume, 
     // overriding the global Slic3r settings and the ModelObject settings.
     DynamicPrintConfig  config;
@@ -377,13 +384,16 @@ public:
     void                rotate(double angle, const Vec3d& axis);
     void                mirror(Axis axis);
 
+    // This method could only be called before the meshes of this ModelVolumes are not shared!
     void                scale_geometry(const Vec3d& versor);
 
-    // translates the mesh and the convex hull so that the origin of their vertices is in the center of this volume's bounding box
-    void                center_geometry();
+    // Translates the mesh and the convex hull so that the origin of their vertices is in the center of this volume's bounding box.
+    // Attention! This method may only be called just after ModelVolume creation! It must not be called once the TriangleMesh of this ModelVolume is shared!
+    void                center_geometry_after_creation();
 
     void                calculate_convex_hull();
     const TriangleMesh& get_convex_hull() const;
+    std::shared_ptr<const TriangleMesh> get_convex_hull_shared_ptr() const { return m_convex_hull; }
     // Get count of errors in the mesh
     int                 get_mesh_errors_count() const;
 
@@ -430,18 +440,20 @@ protected:
 
 	explicit ModelVolume(const ModelVolume &rhs) = default;
     void     set_model_object(ModelObject *model_object) { object = model_object; }
-    void     transform_mesh(const Transform3d& t, bool fix_left_handed);
-    void     transform_mesh(const Matrix3d& m, bool fix_left_handed);
+    void     transform_this_mesh(const Transform3d& t, bool fix_left_handed);
+    void     transform_this_mesh(const Matrix3d& m, bool fix_left_handed);
 
 private:
     // Parent object owning this ModelVolume.
-    ModelObject*            object;
+    ModelObject*                    object;
+    // The triangular model.
+    std::shared_ptr<TriangleMesh>   m_mesh;
     // Is it an object to be printed, or a modifier volume?
-    ModelVolumeType         m_type;
-    t_model_material_id     m_material_id;
+    ModelVolumeType                 m_type;
+    t_model_material_id             m_material_id;
     // The convex hull of this model's mesh.
-    TriangleMesh             m_convex_hull;
-    Geometry::Transformation m_transformation;
+    std::shared_ptr<TriangleMesh>   m_convex_hull;
+    Geometry::Transformation        m_transformation;
 
     // flag to optimize the checking if the volume is splittable
     //     -1   ->   is unknown value (before first cheking)
@@ -449,24 +461,24 @@ private:
     //      1   ->   is splittable
     mutable int               m_is_splittable{ -1 };
 
-	ModelVolume(ModelObject *object, const TriangleMesh &mesh) : mesh(mesh), m_type(ModelVolumeType::MODEL_PART), object(object)
+	ModelVolume(ModelObject *object, const TriangleMesh &mesh) : m_mesh(new TriangleMesh(mesh)), m_type(ModelVolumeType::MODEL_PART), object(object)
     {
         if (mesh.stl.stats.number_of_facets > 1)
             calculate_convex_hull();
     }
     ModelVolume(ModelObject *object, TriangleMesh &&mesh, TriangleMesh &&convex_hull) :
-		mesh(std::move(mesh)), m_convex_hull(std::move(convex_hull)), m_type(ModelVolumeType::MODEL_PART), object(object) {}
+		m_mesh(new TriangleMesh(std::move(mesh))), m_convex_hull(new TriangleMesh(std::move(convex_hull))), m_type(ModelVolumeType::MODEL_PART), object(object) {}
 
     // Copying an existing volume, therefore this volume will get a copy of the ID assigned.
     ModelVolume(ModelObject *object, const ModelVolume &other) :
         ModelBase(other), // copy the ID
-        name(other.name), mesh(other.mesh), m_convex_hull(other.m_convex_hull), config(other.config), m_type(other.m_type), object(object), m_transformation(other.m_transformation)
+        name(other.name), m_mesh(other.m_mesh), m_convex_hull(other.m_convex_hull), config(other.config), m_type(other.m_type), object(object), m_transformation(other.m_transformation)
     {
         this->set_material_id(other.material_id());
     }
     // Providing a new mesh, therefore this volume will get a new unique ID assigned.
     ModelVolume(ModelObject *object, const ModelVolume &other, const TriangleMesh &&mesh) :
-        name(other.name), mesh(std::move(mesh)), config(other.config), m_type(other.m_type), object(object), m_transformation(other.m_transformation)
+        name(other.name), m_mesh(new TriangleMesh(std::move(mesh))), config(other.config), m_type(other.m_type), object(object), m_transformation(other.m_transformation)
     {
         this->set_material_id(other.material_id());
         if (mesh.stl.stats.number_of_facets > 1)
@@ -597,10 +609,6 @@ public:
     static Model read_from_file(const std::string &input_file, DynamicPrintConfig *config = nullptr, bool add_default_instances = true);
     static Model read_from_archive(const std::string &input_file, DynamicPrintConfig *config, bool add_default_instances = true);
 
-    /// Repair the ModelObjects of the current Model.
-    /// This function calls repair function on each TriangleMesh of each model object volume
-    void         repair();
-
     // Add a new ModelObject to this Model, generate a new ID for this ModelObject.
     ModelObject* add_object();
     ModelObject* add_object(const char *name, const char *path, const TriangleMesh &mesh);
diff --git a/src/libslic3r/ModelArrange.cpp b/src/libslic3r/ModelArrange.cpp
index b088a1f17..a440c3999 100644
--- a/src/libslic3r/ModelArrange.cpp
+++ b/src/libslic3r/ModelArrange.cpp
@@ -9,6 +9,31 @@
 #include <ClipperUtils.hpp>
 
 #include <boost/geometry/index/rtree.hpp>
+#include <boost/multiprecision/integer.hpp>
+#include <boost/rational.hpp>
+
+namespace libnest2d {
+#if !defined(_MSC_VER) && defined(__SIZEOF_INT128__) && !defined(__APPLE__)
+using LargeInt = __int128;
+#else
+using LargeInt = boost::multiprecision::int128_t;
+template<> struct _NumTag<LargeInt> { using Type = ScalarTag; };
+#endif
+template<class T> struct _NumTag<boost::rational<T>> { using Type = RationalTag; };
+
+namespace nfp {
+
+template<class S>
+struct NfpImpl<S, NfpLevel::CONVEX_ONLY>
+{
+    NfpResult<S> operator()(const S &sh, const S &other)
+    {
+        return nfpConvexOnly<S, boost::rational<LargeInt>>(sh, other);
+    }
+};
+
+}
+}
 
 namespace Slic3r {
 
@@ -130,7 +155,7 @@ Box boundingBox(const Box& pilebb, const Box& ibb ) {
 // at the same time, it has to provide reasonable results.
 std::tuple<double /*score*/, Box /*farthest point from bin center*/>
 objfunc(const PointImpl& bincenter,
-        const shapelike::Shapes<PolygonImpl>& merged_pile,
+        const TMultiShape<PolygonImpl>& merged_pile,
         const Box& pilebb,
         const ItemGroup& items,
         const Item &item,
@@ -293,7 +318,7 @@ class AutoArranger {};
 // management and spatial index structures for acceleration.
 template<class TBin>
 class _ArrBase {
-protected:
+public:
 
     // Useful type shortcuts...
     using Placer = TPacker<TBin>;
@@ -301,7 +326,9 @@ protected:
     using Packer = Nester<Placer, Selector>;
     using PConfig = typename Packer::PlacementConfig;
     using Distance = TCoord<PointImpl>;
-    using Pile = sl::Shapes<PolygonImpl>;
+    using Pile = TMultiShape<PolygonImpl>;
+    
+protected:
 
     Packer m_pck;
     PConfig m_pconf;            // Placement configuration
@@ -539,7 +566,10 @@ public:
 // 2D shape from top view.
 using ShapeData2D = std::vector<std::pair<Slic3r::ModelInstance*, Item>>;
 
-ShapeData2D projectModelFromTop(const Slic3r::Model &model, const WipeTowerInfo& wti) {
+ShapeData2D projectModelFromTop(const Slic3r::Model &model,
+                                const WipeTowerInfo &wti,
+                                double               tolerance)
+{
     ShapeData2D ret;
 
     // Count all the items on the bin (all the object's instances)
@@ -561,21 +591,32 @@ ShapeData2D projectModelFromTop(const Slic3r::Model &model, const WipeTowerInfo&
             // Object instances should carry the same scaling and
             // x, y rotation that is why we use the first instance.
             {
-                ModelInstance *finst = objptr->instances.front();
-                Vec3d rotation = finst->get_rotation();
-                rotation.z() = 0.;
-                Transform3d trafo_instance = Geometry::assemble_transform(Vec3d::Zero(), rotation, finst->get_scaling_factor(), finst->get_mirror());
+                ModelInstance *finst       = objptr->instances.front();
+                Vec3d          rotation    = finst->get_rotation();
+                rotation.z()               = 0.;
+                Transform3d trafo_instance = Geometry::assemble_transform(
+                    Vec3d::Zero(),
+                    rotation,
+                    finst->get_scaling_factor(),
+                    finst->get_mirror());
                 Polygon p = objptr->convex_hull_2d(trafo_instance);
-				assert(! p.points.empty());
-
-                // this may happen for malformed models, see: https://github.com/prusa3d/PrusaSlicer/issues/2209
-                if (p.points.empty())
-                    continue;
+                
+                assert(!p.points.empty());
 
+                // this may happen for malformed models, see:
+                // https://github.com/prusa3d/PrusaSlicer/issues/2209
+                if (p.points.empty()) continue;
+                
+                if(tolerance > EPSILON) {
+                    Polygons pp { p };
+                    pp = p.simplify(double(scaled(tolerance)));
+                    if (!pp.empty()) p = pp.front();
+                }
+                
                 p.reverse();
                 assert(!p.is_counter_clockwise());
-                p.append(p.first_point());
                 clpath = Slic3rMultiPoint_to_ClipperPath(p);
+                auto firstp = clpath.front(); clpath.emplace_back(firstp);
             }
 
             Vec3d rotation0 = objptr->instances.front()->get_rotation();
@@ -589,7 +630,7 @@ ShapeData2D projectModelFromTop(const Slic3r::Model &model, const WipeTowerInfo&
 
                 // Invalid geometries would throw exceptions when arranging
                 if(item.vertexCount() > 3) {
-                    item.rotation(float(Geometry::rotation_diff_z(rotation0, objinst->get_rotation()))),
+                    item.rotation(Geometry::rotation_diff_z(rotation0, objinst->get_rotation()));
                     item.translation({
                     ClipperLib::cInt(objinst->get_offset(X)/SCALING_FACTOR),
                     ClipperLib::cInt(objinst->get_offset(Y)/SCALING_FACTOR)
@@ -741,6 +782,8 @@ BedShapeHint bedShape(const Polyline &bed) {
     return ret;
 }
 
+static const SLIC3R_CONSTEXPR double SIMPLIFY_TOLERANCE_MM = 0.1;
+
 // The final client function to arrange the Model. A progress indicator and
 // a stop predicate can be also be passed to control the process.
 bool arrange(Model &model,              // The model with the geometries
@@ -755,9 +798,9 @@ bool arrange(Model &model,              // The model with the geometries
              std::function<bool ()> stopcondition)
 {
     bool ret = true;
-
+    
     // Get the 2D projected shapes with their 3D model instance pointers
-    auto shapemap = arr::projectModelFromTop(model, wti);
+    auto shapemap = arr::projectModelFromTop(model, wti, SIMPLIFY_TOLERANCE_MM);
 
     // Copy the references for the shapes only as the arranger expects a
     // sequence of objects convertible to Item or ClipperPolygon
@@ -782,7 +825,7 @@ bool arrange(Model &model,              // The model with the geometries
                          static_cast<libnest2d::Coord>(bbb.min(0)),
                          static_cast<libnest2d::Coord>(bbb.min(1))
                      },
-    {
+                     {
                          static_cast<libnest2d::Coord>(bbb.max(0)),
                          static_cast<libnest2d::Coord>(bbb.max(1))
                      });
@@ -856,9 +899,9 @@ void find_new_position(const Model &model,
                        coord_t min_obj_distance,
                        const Polyline &bed,
                        WipeTowerInfo& wti)
-{
+{    
     // Get the 2D projected shapes with their 3D model instance pointers
-    auto shapemap = arr::projectModelFromTop(model, wti);
+    auto shapemap = arr::projectModelFromTop(model, wti, SIMPLIFY_TOLERANCE_MM);
 
     // Copy the references for the shapes only as the arranger expects a
     // sequence of objects convertible to Item or ClipperPolygon
diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index 377d53bef..f159ea7b7 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -2258,6 +2258,20 @@ void PrintConfigDef::init_sla_params()
     def->min = 100;
     def->set_default_value(new ConfigOptionInt(1440));
 
+    def = this->add("display_mirror_x", coBool);
+    def->full_label = L("Display horizontal mirroring");
+    def->label = L("Mirror horizontally");
+    def->tooltip = L("Enable horizontal mirroring of output images");
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionBool(true));
+
+    def = this->add("display_mirror_y", coBool);
+    def->full_label = L("Display vertical mirroring");
+    def->label = L("Mirror vertically");
+    def->tooltip = L("Enable vertical mirroring of output images");
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionBool(false));
+
     def = this->add("display_orientation", coEnum);
     def->label = L("Display orientation");
     def->tooltip = L("Set the actual LCD display orientation inside the SLA printer."
diff --git a/src/libslic3r/PrintConfig.hpp b/src/libslic3r/PrintConfig.hpp
index b5ddc4f13..3bf5c5af7 100644
--- a/src/libslic3r/PrintConfig.hpp
+++ b/src/libslic3r/PrintConfig.hpp
@@ -1111,6 +1111,8 @@ public:
     ConfigOptionInt                         display_pixels_x;
     ConfigOptionInt                         display_pixels_y;
     ConfigOptionEnum<SLADisplayOrientation> display_orientation;
+    ConfigOptionBool                        display_mirror_x;
+    ConfigOptionBool                        display_mirror_y;
     ConfigOptionFloats                      relative_correction;
     ConfigOptionFloat                       absolute_correction;
     ConfigOptionFloat                       gamma_correction;
@@ -1127,6 +1129,8 @@ protected:
         OPT_PTR(display_height);
         OPT_PTR(display_pixels_x);
         OPT_PTR(display_pixels_y);
+        OPT_PTR(display_mirror_x);
+        OPT_PTR(display_mirror_y);
         OPT_PTR(display_orientation);
         OPT_PTR(relative_correction);
         OPT_PTR(absolute_correction);
diff --git a/src/libslic3r/PrintExport.hpp b/src/libslic3r/PrintExport.hpp
deleted file mode 100644
index f6537ed32..000000000
--- a/src/libslic3r/PrintExport.hpp
+++ /dev/null
@@ -1,327 +0,0 @@
-#ifndef PRINTEXPORT_HPP
-#define PRINTEXPORT_HPP
-
-// For png export of the sliced model
-#include <fstream>
-#include <sstream>
-#include <vector>
-
-#include <boost/log/trivial.hpp>
-#include <boost/filesystem/path.hpp>
-
-#include "Rasterizer/Rasterizer.hpp"
-//#include <tbb/parallel_for.h>
-//#include <tbb/spin_mutex.h>//#include "tbb/mutex.h"
-
-namespace Slic3r {
-
-// Used for addressing parameters of FilePrinter::set_statistics()
-enum ePrintStatistics
-{
-    psUsedMaterial = 0,
-    psNumFade,
-    psNumSlow,
-    psNumFast,
-
-    psCnt
-};
-
-enum class FilePrinterFormat {
-    SLA_PNGZIP,
-    SVG
-};
-
-/*
- * Interface for a file printer of the slices. Implementation can be an SVG
- * or PNG printer or any other format.
- *
- * The format argument specifies the output format of the printer and it enables
- * different implementations of this class template for each supported format.
- *
- */
-template<FilePrinterFormat format>
-class FilePrinter {
-public:
-
-    // Draw a polygon which is a polygon inside a slice on the specified layer.
-    void draw_polygon(const ExPolygon& p, unsigned lyr);
-    void draw_polygon(const ClipperLib::Polygon& p, unsigned lyr);
-
-    // Tell the printer how many layers should it consider.
-    void layers(unsigned layernum);
-
-    // Get the number of layers in the print.
-    unsigned layers() const;
-
-    /* Switch to a particular layer. If there where less layers then the
-     * specified layer number than an appropriate number of layers will be
-     * allocated in the printer.
-     */
-    void begin_layer(unsigned layer);
-
-    // Allocate a new layer on top of the last and switch to it.
-    void begin_layer();
-
-    /*
-     * Finish the selected layer. It means that no drawing is allowed on that
-     * layer anymore. This fact can be used to prepare the file system output
-     * data like png comprimation and so on.
-     */
-    void finish_layer(unsigned layer);
-
-    // Finish the top layer.
-    void finish_layer();
-
-    // Save all the layers into the file (or dir) specified in the path argument
-    // An optional project name can be added to be used for the layer file names
-    void save(const std::string& path, const std::string& projectname = "");
-
-    // Save only the selected layer to the file specified in path argument.
-    void save_layer(unsigned lyr, const std::string& path);
-};
-
-// Provokes static_assert in the right way.
-template<class T = void> struct VeryFalse { static const bool value = false; };
-
-// This can be explicitly implemented in the gui layer or the default Zipper
-// API in libslic3r with minz.
-template<class Fmt> class LayerWriter {
-public:
-
-    LayerWriter(const std::string& /*zipfile_path*/)
-    {
-        static_assert(VeryFalse<Fmt>::value,
-                      "No layer writer implementation provided!");
-    }
-
-    // Should create a new file within the zip with the given filename. It
-    // should also finish any previous entry.
-    void next_entry(const std::string& /*fname*/) {}
-
-    // Should create a new file within the archive and write the provided data.
-    void binary_entry(const std::string& /*fname*/,
-                      const std::uint8_t* buf, size_t len);
-
-    // Test whether the object can still be used for writing.
-    bool is_ok() { return false; }
-
-    // Write some data (text) into the current file (entry) within the archive.
-    template<class T> LayerWriter& operator<<(T&& /*arg*/) {
-        return *this;
-    }
-
-    // Flush the current entry into the archive.
-    void finalize() {}
-};
-
-// Implementation for PNG raster output
-// Be aware that if a large number of layers are allocated, it can very well
-// exhaust the available memory especially on 32 bit platform.
-template<> class FilePrinter<FilePrinterFormat::SLA_PNGZIP>
-{
-    struct Layer {
-        Raster raster;
-        RawBytes rawbytes;
-
-        Layer() {}
-
-        Layer(const Layer&) = delete;
-        Layer(Layer&& m):
-            raster(std::move(m.raster)) {}
-    };
-
-    // We will save the compressed PNG data into stringstreams which can be done
-    // in parallel. Later we can write every layer to the disk sequentially.
-    std::vector<Layer> m_layers_rst;
-    Raster::Resolution m_res;
-    Raster::PixelDim m_pxdim;
-    double m_exp_time_s = .0, m_exp_time_first_s = .0;
-    double m_layer_height = .0;
-    Raster::Origin m_o = Raster::Origin::TOP_LEFT;
-    double m_gamma;
-
-    double m_used_material = 0.0;
-    int    m_cnt_fade_layers = 0;
-    int    m_cnt_slow_layers = 0;
-    int    m_cnt_fast_layers = 0;
-
-    std::string createIniContent(const std::string& projectname) {
-        using std::string;
-        using std::to_string;
-
-        auto expt_str = to_string(m_exp_time_s);
-        auto expt_first_str = to_string(m_exp_time_first_s);
-        auto layerh_str = to_string(m_layer_height);
-
-        const std::string cnt_fade_layers = to_string(m_cnt_fade_layers);
-        const std::string cnt_slow_layers = to_string(m_cnt_slow_layers);
-        const std::string cnt_fast_layers = to_string(m_cnt_fast_layers);
-        const std::string used_material   = to_string(m_used_material);
-
-        return string(
-        "action = print\n"
-        "jobDir = ") + projectname + "\n" +
-        "expTime = " + expt_str + "\n"
-        "expTimeFirst = " + expt_first_str + "\n"
-        "numFade = " + cnt_fade_layers + "\n"
-        "layerHeight = " + layerh_str + "\n"
-        "usedMaterial = " + used_material + "\n"
-        "numSlow = " + cnt_slow_layers + "\n"
-        "numFast = " + cnt_fast_layers + "\n";
-    }
-
-public:
-
-    enum RasterOrientation {
-        RO_LANDSCAPE,
-        RO_PORTRAIT
-    };
-
-    // We will play with the raster's coordinate origin parameter. When the
-    // printer should print in landscape mode it should have the Y axis flipped
-    // because the layers should be displayed upside down. PNG has its
-    // coordinate origin in the top-left corner so normally the Raster objects
-    // should be instantiated with the TOP_LEFT flag. However, in landscape mode
-    // we do want the pictures to be upside down so we will make BOTTOM_LEFT
-    // type rasters and the PNG format will do the flipping automatically.
-
-    // In case of portrait images, we have to rotate the image by a 90 degrees
-    // and flip the y axis. To get the correct upside-down orientation of the
-    // slice images, we can flip the x and y coordinates of the input polygons
-    // and do the Y flipping of the image. This will generate the correct
-    // orientation in portrait mode.
-
-    inline FilePrinter(double width_mm, double height_mm,
-                       unsigned width_px, unsigned height_px,
-                       double layer_height,
-                       double exp_time, double exp_time_first,
-                       RasterOrientation ro = RO_PORTRAIT,
-                       double gamma = 1.0):
-        m_res(width_px, height_px),
-        m_pxdim(width_mm/width_px, height_mm/height_px),
-        m_exp_time_s(exp_time),
-        m_exp_time_first_s(exp_time_first),
-        m_layer_height(layer_height),
-
-        // Here is the trick with the orientation.
-        m_o(ro == RO_LANDSCAPE? Raster::Origin::BOTTOM_LEFT :
-                                Raster::Origin::TOP_LEFT ),
-        m_gamma(gamma)
-    {
-    }
-
-    FilePrinter(const FilePrinter& ) = delete;
-    FilePrinter(FilePrinter&& m):
-        m_layers_rst(std::move(m.m_layers_rst)),
-        m_res(m.m_res),
-        m_pxdim(m.m_pxdim) {}
-
-    inline void layers(unsigned cnt) { if(cnt > 0) m_layers_rst.resize(cnt); }
-    inline unsigned layers() const { return unsigned(m_layers_rst.size()); }
-
-    inline void draw_polygon(const ExPolygon& p, unsigned lyr) {
-        assert(lyr < m_layers_rst.size());
-        m_layers_rst[lyr].raster.draw(p);
-    }
-
-    inline void draw_polygon(const ClipperLib::Polygon& p, unsigned lyr) {
-        assert(lyr < m_layers_rst.size());
-        m_layers_rst[lyr].raster.draw(p);
-    }
-
-    inline void begin_layer(unsigned lyr) {
-        if(m_layers_rst.size() <= lyr) m_layers_rst.resize(lyr+1);
-        m_layers_rst[lyr].raster.reset(m_res, m_pxdim, m_o, m_gamma);
-    }
-
-    inline void begin_layer() {
-        m_layers_rst.emplace_back();
-        m_layers_rst.front().raster.reset(m_res, m_pxdim, m_o, m_gamma);
-    }
-
-    inline void finish_layer(unsigned lyr_id) {
-        assert(lyr_id < m_layers_rst.size());
-        m_layers_rst[lyr_id].rawbytes =
-                m_layers_rst[lyr_id].raster.save(Raster::Compression::PNG);
-        m_layers_rst[lyr_id].raster.reset();
-    }
-
-    inline void finish_layer() {
-        if(!m_layers_rst.empty()) {
-            m_layers_rst.back().rawbytes =
-                    m_layers_rst.back().raster.save(Raster::Compression::PNG);
-            m_layers_rst.back().raster.reset();
-        }
-    }
-
-    template<class LyrFmt>
-    inline void save(const std::string& fpath, const std::string& prjname = "")
-    {
-        try {
-            LayerWriter<LyrFmt> writer(fpath);
-            if(!writer.is_ok()) return;
-
-            std::string project = prjname.empty()?
-                       boost::filesystem::path(fpath).stem().string() : prjname;
-
-            writer.next_entry("config.ini");
-            if(!writer.is_ok()) return;
-
-            writer << createIniContent(project);
-
-            for(unsigned i = 0; i < m_layers_rst.size() && writer.is_ok(); i++)
-            {
-                if(m_layers_rst[i].rawbytes.size() > 0) {
-                    char lyrnum[6];
-                    std::sprintf(lyrnum, "%.5d", i);
-                    auto zfilename = project + lyrnum + ".png";
-                    if(!writer.is_ok()) break;
-
-                    writer.binary_entry(zfilename,
-                                        m_layers_rst[i].rawbytes.data(),
-                                        m_layers_rst[i].rawbytes.size());
-                }
-            }
-
-            writer.finalize();
-        } catch(std::exception& e) {
-            BOOST_LOG_TRIVIAL(error) << e.what();
-            // Rethrow the exception
-            throw;
-        }
-    }
-
-    void save_layer(unsigned lyr, const std::string& path) {
-        unsigned i = lyr;
-        assert(i < m_layers_rst.size());
-
-        char lyrnum[6];
-        std::sprintf(lyrnum, "%.5d", lyr);
-        std::string loc = path + "layer" + lyrnum + ".png";
-
-        std::fstream out(loc, std::fstream::out | std::fstream::binary);
-        if(out.good()) {
-            m_layers_rst[i].raster.save(out, Raster::Compression::PNG);
-        } else {
-            BOOST_LOG_TRIVIAL(error) << "Can't create file for layer";
-        }
-
-        out.close();
-        m_layers_rst[i].raster.reset();
-    }
-
-    void set_statistics(const std::vector<double> statistics)
-    {
-        if (statistics.size() != psCnt)
-            return;
-
-        m_used_material   = statistics[psUsedMaterial];
-        m_cnt_fade_layers = int(statistics[psNumFade]);
-        m_cnt_slow_layers = int(statistics[psNumSlow]);
-        m_cnt_fast_layers = int(statistics[psNumFast]);
-    }
-};
-
-}
-
-#endif // PRINTEXPORT_HPP
diff --git a/src/libslic3r/PrintObject.cpp b/src/libslic3r/PrintObject.cpp
index 660a2d939..d99aceabf 100644
--- a/src/libslic3r/PrintObject.cpp
+++ b/src/libslic3r/PrintObject.cpp
@@ -1797,7 +1797,7 @@ std::vector<ExPolygons> PrintObject::_slice_volumes(const std::vector<float> &z,
     if (! volumes.empty()) {
         // Compose mesh.
         //FIXME better to perform slicing over each volume separately and then to use a Boolean operation to merge them.
-		TriangleMesh mesh(volumes.front()->mesh);
+		TriangleMesh mesh(volumes.front()->mesh());
         mesh.transform(volumes.front()->get_matrix(), true);
 		assert(mesh.repaired);
 		if (volumes.size() == 1 && mesh.repaired) {
@@ -1806,7 +1806,7 @@ std::vector<ExPolygons> PrintObject::_slice_volumes(const std::vector<float> &z,
 		}
         for (size_t idx_volume = 1; idx_volume < volumes.size(); ++ idx_volume) {
             const ModelVolume &model_volume = *volumes[idx_volume];
-            TriangleMesh vol_mesh(model_volume.mesh);
+            TriangleMesh vol_mesh(model_volume.mesh());
             vol_mesh.transform(model_volume.get_matrix(), true);
             mesh.merge(vol_mesh);
         }
@@ -1815,10 +1815,11 @@ std::vector<ExPolygons> PrintObject::_slice_volumes(const std::vector<float> &z,
             // apply XY shift
             mesh.translate(- unscale<float>(m_copies_shift(0)), - unscale<float>(m_copies_shift(1)), 0);
             // perform actual slicing
-            TriangleMeshSlicer mslicer;
             const Print *print = this->print();
             auto callback = TriangleMeshSlicer::throw_on_cancel_callback_type([print](){print->throw_if_canceled();});
-            mesh.require_shared_vertices(); // TriangleMeshSlicer needs this
+            // TriangleMeshSlicer needs shared vertices, also this calls the repair() function.
+            mesh.require_shared_vertices();
+            TriangleMeshSlicer mslicer;
             mslicer.init(&mesh, callback);
 			mslicer.slice(z, float(m_config.slice_closing_radius.value), &layers, callback);
             m_print->throw_if_canceled();
@@ -1832,7 +1833,7 @@ std::vector<ExPolygons> PrintObject::_slice_volume(const std::vector<float> &z,
     std::vector<ExPolygons> layers;
     // Compose mesh.
     //FIXME better to perform slicing over each volume separately and then to use a Boolean operation to merge them.
-    TriangleMesh mesh(volume.mesh);
+    TriangleMesh mesh(volume.mesh());
     mesh.transform(volume.get_matrix(), true);
 	if (mesh.repaired) {
 		//FIXME The admesh repair function may break the face connectivity, rather refresh it here as the slicing code relies on it.
@@ -1846,7 +1847,8 @@ std::vector<ExPolygons> PrintObject::_slice_volume(const std::vector<float> &z,
         TriangleMeshSlicer mslicer;
         const Print *print = this->print();
         auto callback = TriangleMeshSlicer::throw_on_cancel_callback_type([print](){print->throw_if_canceled();});
-        mesh.require_shared_vertices(); // TriangleMeshSlicer needs this
+        // TriangleMeshSlicer needs the shared vertices.
+        mesh.require_shared_vertices();
         mslicer.init(&mesh, callback);
         mslicer.slice(z, float(m_config.slice_closing_radius.value), &layers, callback);
         m_print->throw_if_canceled();
diff --git a/src/libslic3r/Rasterizer/Rasterizer.cpp b/src/libslic3r/SLA/SLARaster.cpp
similarity index 72%
rename from src/libslic3r/Rasterizer/Rasterizer.cpp
rename to src/libslic3r/SLA/SLARaster.cpp
index e1213555c..32a88b1b5 100644
--- a/src/libslic3r/Rasterizer/Rasterizer.cpp
+++ b/src/libslic3r/SLA/SLARaster.cpp
@@ -1,5 +1,10 @@
-#include "Rasterizer.hpp"
-#include <ExPolygon.hpp>
+#ifndef SLARASTER_CPP
+#define SLARASTER_CPP
+
+#include <functional>
+
+#include "SLARaster.hpp"
+#include "libslic3r/ExPolygon.hpp"
 #include <libnest2d/backends/clipper/clipper_polygon.hpp>
 
 // For rasterizing
@@ -19,11 +24,13 @@
 
 namespace Slic3r {
 
-const Polygon& contour(const ExPolygon& p) { return p.contour; }
-const ClipperLib::Path& contour(const ClipperLib::Polygon& p) { return p.Contour; }
+inline const Polygon& contour(const ExPolygon& p) { return p.contour; }
+inline const ClipperLib::Path& contour(const ClipperLib::Polygon& p) { return p.Contour; }
 
-const Polygons& holes(const ExPolygon& p) { return p.holes; }
-const ClipperLib::Paths& holes(const ClipperLib::Polygon& p) { return p.Holes; }
+inline const Polygons& holes(const ExPolygon& p) { return p.holes; }
+inline const ClipperLib::Paths& holes(const ClipperLib::Polygon& p) { return p.Holes; }
+
+namespace sla {
 
 class Raster::Impl {
 public:
@@ -39,7 +46,7 @@ public:
     static const TPixel ColorWhite;
     static const TPixel ColorBlack;
 
-    using Origin = Raster::Origin;
+    using Format = Raster::Format;
 
 private:
     Raster::Resolution m_resolution;
@@ -52,16 +59,21 @@ private:
     TRendererAA m_renderer;
     
     std::function<double(double)> m_gammafn;
-    Origin m_o;
+    std::array<bool, 2> m_mirror;
+    Format m_fmt = Format::PNG;
     
     inline void flipy(agg::path_storage& path) const {
         path.flip_y(0, m_resolution.height_px);
     }
+    
+    inline void flipx(agg::path_storage& path) const {
+        path.flip_x(0, m_resolution.width_px);
+    }
 
 public:
 
     inline Impl(const Raster::Resolution& res, const Raster::PixelDim &pd,
-                Origin o, double gamma = 1.0):
+                const std::array<bool, 2>& mirror, double gamma = 1.0):
         m_resolution(res), 
 //        m_pxdim(pd), 
         m_pxdim_scaled(SCALING_FACTOR / pd.w_mm, SCALING_FACTOR / pd.h_mm),
@@ -72,7 +84,7 @@ public:
         m_pixfmt(m_rbuf),
         m_raw_renderer(m_pixfmt),
         m_renderer(m_raw_renderer),
-        m_o(o)
+        m_mirror(mirror)
     {
         m_renderer.color(ColorWhite);
         
@@ -81,6 +93,19 @@ public:
         
         clear();
     }
+    
+    inline Impl(const Raster::Resolution& res, 
+                const Raster::PixelDim &pd,
+                Format fmt, 
+                double gamma = 1.0): 
+        Impl(res, pd, {false, false}, gamma) 
+    {
+        switch (fmt) {
+        case Format::PNG: m_mirror = {false, true}; break;
+        case Format::RAW: m_mirror = {false, false}; break;
+        }
+        m_fmt = fmt;
+    }
 
     template<class P> void draw(const P &poly) {
         agg::rasterizer_scanline_aa<> ras;
@@ -89,14 +114,16 @@ public:
         ras.gamma(m_gammafn);
 
         auto&& path = to_path(contour(poly));
-
-        if(m_o == Origin::TOP_LEFT) flipy(path);
+        
+        if(m_mirror[X]) flipx(path);
+        if(m_mirror[Y]) flipy(path);
 
         ras.add_path(path);
 
         for(auto& h : holes(poly)) {
             auto&& holepath = to_path(h);
-            if(m_o == Origin::TOP_LEFT) flipy(holepath);
+            if(m_mirror[X]) flipx(holepath);
+            if(m_mirror[Y]) flipy(holepath);
             ras.add_path(holepath);
         }
 
@@ -108,11 +135,11 @@ public:
     }
 
     inline TBuffer& buffer()  { return m_buf; }
+    
+    inline Format format() const { return m_fmt; }
 
     inline const Raster::Resolution resolution() { return m_resolution; }
-
-    inline Origin origin() const /*noexcept*/ { return m_o; }
-
+   
 private:
     inline double getPx(const Point& p) {
         return p(0) * m_pxdim_scaled.w_mm;
@@ -154,30 +181,30 @@ private:
 const Raster::Impl::TPixel Raster::Impl::ColorWhite = Raster::Impl::TPixel(255);
 const Raster::Impl::TPixel Raster::Impl::ColorBlack = Raster::Impl::TPixel(0);
 
-Raster::Raster(const Resolution &r, const PixelDim &pd, Origin o, double g):
-    m_impl(new Impl(r, pd, o, g)) {}
+template<> Raster::Raster() { reset(); };
+Raster::~Raster() = default;
 
-Raster::Raster() {}
+// Raster::Raster(Raster &&m) = default;
+// Raster& Raster::operator=(Raster&&) = default;
 
-Raster::~Raster() {}
-
-Raster::Raster(Raster &&m):
-    m_impl(std::move(m.m_impl)) {}
-
-void Raster::reset(const Raster::Resolution &r, const Raster::PixelDim &pd, 
-                   double g)
-{
-    // Free up the unnecessary memory and make sure it stays clear after
-    // an exception
-    auto o = m_impl? m_impl->origin() : Origin::TOP_LEFT;
-    reset(r, pd, o, g);
+// FIXME: remove after migrating to higher version of windows compiler
+Raster::Raster(Raster &&m): m_impl(std::move(m.m_impl)) {}
+Raster& Raster::operator=(Raster &&m) {
+    m_impl = std::move(m.m_impl); return *this;
 }
 
 void Raster::reset(const Raster::Resolution &r, const Raster::PixelDim &pd,
-                   Raster::Origin o, double gamma)
+                   Format fmt, double gamma)
 {
     m_impl.reset();
-    m_impl.reset(new Impl(r, pd, o, gamma));
+    m_impl.reset(new Impl(r, pd, fmt, gamma));
+}
+
+void Raster::reset(const Raster::Resolution &r, const Raster::PixelDim &pd,
+                   const std::array<bool, 2>& mirror, double gamma)
+{
+    m_impl.reset();
+    m_impl.reset(new Impl(r, pd, mirror, gamma));
 }
 
 void Raster::reset()
@@ -208,13 +235,13 @@ void Raster::draw(const ClipperLib::Polygon &poly)
     m_impl->draw(poly);
 }
 
-void Raster::save(std::ostream& stream, Compression comp)
+void Raster::save(std::ostream& stream, Format fmt)
 {
     assert(m_impl);
     if(!stream.good()) return;
 
-    switch(comp) {
-    case Compression::PNG: {
+    switch(fmt) {
+    case Format::PNG: {
         auto& b = m_impl->buffer();
         size_t out_len = 0;
         void * rawdata = tdefl_write_image_to_png_file_in_memory(
@@ -231,7 +258,7 @@ void Raster::save(std::ostream& stream, Compression comp)
 
         break;
     }
-    case Compression::RAW: {
+    case Format::RAW: {
         stream << "P5 "
                << m_impl->resolution().width_px << " "
                << m_impl->resolution().height_px << " "
@@ -244,14 +271,19 @@ void Raster::save(std::ostream& stream, Compression comp)
     }
 }
 
-RawBytes Raster::save(Raster::Compression comp)
+void Raster::save(std::ostream &stream)
+{
+    save(stream, m_impl->format());
+}
+
+RawBytes Raster::save(Format fmt)
 {
     assert(m_impl);
 
     std::vector<std::uint8_t> data; size_t s = 0;
 
-    switch(comp) {
-    case Compression::PNG: {
+    switch(fmt) {
+    case Format::PNG: {
         void *rawdata = tdefl_write_image_to_png_file_in_memory(
                     m_impl->buffer().data(),
                     int(resolution().width_px),
@@ -265,7 +297,7 @@ RawBytes Raster::save(Raster::Compression comp)
         MZ_FREE(rawdata);
         break;
     }
-    case Compression::RAW: {
+    case Format::RAW: {
         auto header = std::string("P5 ") +
                 std::to_string(m_impl->resolution().width_px) + " " +
                 std::to_string(m_impl->resolution().height_px) + " " + "255 ";
@@ -286,4 +318,12 @@ RawBytes Raster::save(Raster::Compression comp)
     return {std::move(data)};
 }
 
+RawBytes Raster::save()
+{
+    return save(m_impl->format());
 }
+
+}
+}
+
+#endif // SLARASTER_CPP
diff --git a/src/libslic3r/Rasterizer/Rasterizer.hpp b/src/libslic3r/SLA/SLARaster.hpp
similarity index 64%
rename from src/libslic3r/Rasterizer/Rasterizer.hpp
rename to src/libslic3r/SLA/SLARaster.hpp
index 3fffe1a36..d3bd52d92 100644
--- a/src/libslic3r/Rasterizer/Rasterizer.hpp
+++ b/src/libslic3r/SLA/SLARaster.hpp
@@ -1,17 +1,21 @@
-#ifndef RASTERIZER_HPP
-#define RASTERIZER_HPP
+#ifndef SLARASTER_HPP
+#define SLARASTER_HPP
 
 #include <ostream>
 #include <memory>
 #include <vector>
+#include <array>
+#include <utility>
 #include <cstdint>
 
 namespace ClipperLib { struct Polygon; }
 
-namespace Slic3r {
+namespace Slic3r { 
 
 class ExPolygon;
 
+namespace sla {
+
 // Raw byte buffer paired with its size. Suitable for compressed PNG data.
 class RawBytes {
 
@@ -23,15 +27,18 @@ public:
     
     size_t size() const { return m_buffer.size(); }
     const uint8_t * data() { return m_buffer.data(); }
+    
+    RawBytes(const RawBytes&) = delete;
+    RawBytes& operator=(const RawBytes&) = delete;
 
     // /////////////////////////////////////////////////////////////////////////
     // FIXME: the following is needed for MSVC2013 compatibility
     // /////////////////////////////////////////////////////////////////////////
 
-    RawBytes(const RawBytes&) = delete;
-    RawBytes(RawBytes&& mv) : m_buffer(std::move(mv.m_buffer)) {}
+    // RawBytes(RawBytes&&) = default;
+    // RawBytes& operator=(RawBytes&&) = default;
 
-    RawBytes& operator=(const RawBytes&) = delete;
+    RawBytes(RawBytes&& mv) : m_buffer(std::move(mv.m_buffer)) {}
     RawBytes& operator=(RawBytes&& mv) {
         m_buffer = std::move(mv.m_buffer);
         return *this;
@@ -54,28 +61,19 @@ class Raster {
 public:
 
     /// Supported compression types
-    enum class Compression {
+    enum class Format {
         RAW,    //!> Uncompressed pixel data
         PNG     //!> PNG compression
     };
 
-    /// The Rasterizer expects the input polygons to have their coordinate
-    /// system origin in the bottom left corner. If the raster is then
-    /// configured with the TOP_LEFT origin parameter (in the constructor) than
-    /// it will flip the Y axis in output to maintain the correct orientation.
-    /// This is the default case with PNG images. They have the origin in the
-    /// top left corner. Without the flipping, the image would be upside down
-    /// with the scaled (clipper) coordinate system of the input polygons.
-    enum class Origin {
-        TOP_LEFT,
-        BOTTOM_LEFT
-    };
-
     /// Type that represents a resolution in pixels.
     struct Resolution {
         unsigned width_px;
         unsigned height_px;
-        inline Resolution(unsigned w, unsigned h): width_px(w), height_px(h) {}
+
+        inline Resolution(unsigned w = 0, unsigned h = 0):
+            width_px(w), height_px(h) {}
+
         inline unsigned pixels() const /*noexcept*/ {
             return width_px * height_px;
         }
@@ -85,24 +83,34 @@ public:
     struct PixelDim {
         double w_mm;
         double h_mm;
-        inline PixelDim(double px_width_mm, double px_height_mm ):
+        inline PixelDim(double px_width_mm = 0.0, double px_height_mm = 0.0):
             w_mm(px_width_mm), h_mm(px_height_mm) {}
     };
 
     /// Constructor taking the resolution and the pixel dimension.
-    Raster(const Resolution& r,  const PixelDim& pd, 
-           Origin o = Origin::BOTTOM_LEFT, double gamma = 1.0);
+    template <class...Args> Raster(Args...args) { 
+        reset(std::forward<Args>(args)...); 
+    }
     
-    Raster();
     Raster(const Raster& cpy) = delete;
     Raster& operator=(const Raster& cpy) = delete;
     Raster(Raster&& m);
+    Raster& operator=(Raster&&);
     ~Raster();
 
     /// Reallocated everything for the given resolution and pixel dimension.
-    void reset(const Resolution& r, const PixelDim& pd, double gamma = 1.0);
-    void reset(const Resolution& r, const PixelDim& pd, Origin o, double gamma);
-
+    /// The third parameter is either the X, Y mirroring or a supported format 
+    /// for which the correct mirroring will be configured.
+    void reset(const Resolution&, 
+               const PixelDim&, 
+               const std::array<bool, 2>& mirror, 
+               double gamma = 1.0);
+    
+    void reset(const Resolution& r, 
+               const PixelDim& pd, 
+               Format o, 
+               double gamma = 1.0);
+    
     /**
      * Release the allocated resources. Drawing in this state ends in
      * unspecified behavior.
@@ -119,11 +127,24 @@ public:
     void draw(const ExPolygon& poly);
     void draw(const ClipperLib::Polygon& poly);
 
+    // Saving the raster: 
+    // It is possible to override the format given in the constructor but
+    // be aware that the mirroring will not be modified.
+    
     /// Save the raster on the specified stream.
-    void save(std::ostream& stream, Compression comp = Compression::RAW);
+    void save(std::ostream& stream, Format);
+    void save(std::ostream& stream);
 
-    RawBytes save(Compression comp = Compression::RAW);
+    /// Save into a continuous byte stream which is returned.
+    RawBytes save(Format fmt);
+    RawBytes save();
 };
 
-}
-#endif // RASTERIZER_HPP
+// This prevents the duplicate default constructor warning on MSVC2013
+template<> Raster::Raster();
+
+
+} // sla
+} // Slic3r
+
+#endif // SLARASTER_HPP
diff --git a/src/libslic3r/SLA/SLARasterWriter.cpp b/src/libslic3r/SLA/SLARasterWriter.cpp
new file mode 100644
index 000000000..f7c3925ac
--- /dev/null
+++ b/src/libslic3r/SLA/SLARasterWriter.cpp
@@ -0,0 +1,136 @@
+#include "SLARasterWriter.hpp"
+#include "libslic3r/Zipper.hpp"
+#include "ExPolygon.hpp"
+#include <libnest2d/backends/clipper/clipper_polygon.hpp>
+
+#include <boost/log/trivial.hpp>
+#include <boost/filesystem/path.hpp>
+
+namespace Slic3r { namespace sla {
+
+std::string SLARasterWriter::createIniContent(const std::string& projectname) const 
+{
+    auto expt_str = std::to_string(m_exp_time_s);
+    auto expt_first_str = std::to_string(m_exp_time_first_s);
+    auto layerh_str = std::to_string(m_layer_height);
+
+    const std::string cnt_fade_layers = std::to_string(m_cnt_fade_layers);
+    const std::string cnt_slow_layers = std::to_string(m_cnt_slow_layers);
+    const std::string cnt_fast_layers = std::to_string(m_cnt_fast_layers);
+    const std::string used_material   = std::to_string(m_used_material);
+
+    return std::string(
+    "action = print\n"
+    "jobDir = ") + projectname + "\n" +
+    "expTime = " + expt_str + "\n"
+    "expTimeFirst = " + expt_first_str + "\n"
+    "numFade = " + cnt_fade_layers + "\n"
+    "layerHeight = " + layerh_str + "\n"
+    "usedMaterial = " + used_material + "\n"
+    "numSlow = " + cnt_slow_layers + "\n"
+                                     "numFast = " + cnt_fast_layers + "\n";
+}
+
+void SLARasterWriter::flpXY(ClipperLib::Polygon &poly)
+{
+    for(auto& p : poly.Contour) std::swap(p.X, p.Y);
+    std::reverse(poly.Contour.begin(), poly.Contour.end());
+    
+    for(auto& h : poly.Holes) {
+        for(auto& p : h) std::swap(p.X, p.Y);
+        std::reverse(h.begin(), h.end());
+    }
+}
+
+void SLARasterWriter::flpXY(ExPolygon &poly)
+{
+    for(auto& p : poly.contour.points) p = Point(p.y(), p.x());
+    std::reverse(poly.contour.points.begin(), poly.contour.points.end());
+    
+    for(auto& h : poly.holes) {
+        for(auto& p : h.points) p = Point(p.y(), p.x());
+        std::reverse(h.points.begin(), h.points.end());
+    }
+}
+
+SLARasterWriter::SLARasterWriter(const SLAPrinterConfig &cfg, 
+                                 const SLAMaterialConfig &mcfg, 
+                                 double layer_height)
+{
+    double w = cfg.display_width.getFloat();
+    double h = cfg.display_height.getFloat();
+    auto pw = unsigned(cfg.display_pixels_x.getInt());
+    auto ph = unsigned(cfg.display_pixels_y.getInt());
+    
+    m_mirror[X] = cfg.display_mirror_x.getBool();
+    
+    // PNG raster will implicitly do an Y mirror
+    m_mirror[Y] = ! cfg.display_mirror_y.getBool();
+        
+    auto ro = cfg.display_orientation.getInt();
+    
+    if(ro == roPortrait) {
+        std::swap(w, h);
+        std::swap(pw, ph);
+        m_o = roPortrait;
+        
+        // XY flipping implicitly does an X mirror
+        m_mirror[X] = ! m_mirror[X];
+    } else m_o = roLandscape;
+    
+    m_res = Raster::Resolution(pw, ph);
+    m_pxdim = Raster::PixelDim(w/pw, h/ph);
+    m_exp_time_s = mcfg.exposure_time.getFloat();
+    m_exp_time_first_s = mcfg.initial_exposure_time.getFloat();
+    m_layer_height = layer_height;
+    
+    m_gamma = cfg.gamma_correction.getFloat();
+}
+
+void SLARasterWriter::save(const std::string &fpath, const std::string &prjname)
+{
+    try {
+        Zipper zipper(fpath); // zipper with no compression
+        
+        std::string project = prjname.empty()?
+                    boost::filesystem::path(fpath).stem().string() : prjname;
+        
+        zipper.add_entry("config.ini");
+        
+        zipper << createIniContent(project);
+        
+        for(unsigned i = 0; i < m_layers_rst.size(); i++)
+        {
+            if(m_layers_rst[i].rawbytes.size() > 0) {
+                char lyrnum[6];
+                std::sprintf(lyrnum, "%.5d", i);
+                auto zfilename = project + lyrnum + ".png";
+                
+                // Add binary entry to the zipper
+                zipper.add_entry(zfilename,
+                                 m_layers_rst[i].rawbytes.data(),
+                                 m_layers_rst[i].rawbytes.size());
+            }
+        }
+        
+        zipper.finalize();
+    } catch(std::exception& e) {
+        BOOST_LOG_TRIVIAL(error) << e.what();
+        // Rethrow the exception
+        throw;
+    }
+}
+
+void SLARasterWriter::set_statistics(const std::vector<double> statistics)
+{
+    if (statistics.size() != psCnt)
+        return;
+    
+    m_used_material   = statistics[psUsedMaterial];
+    m_cnt_fade_layers = int(statistics[psNumFade]);
+    m_cnt_slow_layers = int(statistics[psNumSlow]);
+    m_cnt_fast_layers = int(statistics[psNumFast]);
+}
+
+} // namespace sla
+} // namespace Slic3r
diff --git a/src/libslic3r/SLA/SLARasterWriter.hpp b/src/libslic3r/SLA/SLARasterWriter.hpp
new file mode 100644
index 000000000..7133d2dde
--- /dev/null
+++ b/src/libslic3r/SLA/SLARasterWriter.hpp
@@ -0,0 +1,167 @@
+#ifndef SLARASTERWRITER_HPP
+#define SLARASTERWRITER_HPP
+
+// For png export of the sliced model
+#include <fstream>
+#include <sstream>
+#include <vector>
+#include <array>
+
+#include "libslic3r/PrintConfig.hpp"
+
+#include "SLARaster.hpp"
+
+namespace Slic3r { namespace sla {
+
+// Implementation for PNG raster output
+// Be aware that if a large number of layers are allocated, it can very well
+// exhaust the available memory especially on 32 bit platform.
+// This class is designed to be used in parallel mode. Layers have an ID and
+// each layer can be written and compressed independently (in parallel).
+// At the end when all layers where written, the save method can be used to 
+// write out the result into a zipped archive.
+class SLARasterWriter
+{
+public:
+    enum RasterOrientation {
+        roLandscape,
+        roPortrait
+    };
+    
+    // Used for addressing parameters of set_statistics()
+    enum ePrintStatistics
+    {
+        psUsedMaterial = 0,
+        psNumFade,
+        psNumSlow,
+        psNumFast,
+    
+        psCnt
+    };
+    
+private:
+    
+    // A struct to bind the raster image data and its compressed bytes together.
+    struct Layer {
+        Raster raster;
+        RawBytes rawbytes;
+
+        Layer() = default;
+        Layer(const Layer&) = delete; // The image is big, do not copy by accident
+        Layer& operator=(const Layer&) = delete;
+        
+        // /////////////////////////////////////////////////////////////////////
+        // FIXME: the following is needed for MSVC2013 compatibility
+        // /////////////////////////////////////////////////////////////////////
+
+        // Layer(Layer&& m) = default;
+        // Layer& operator=(Layer&&) = default;
+        Layer(Layer &&m):
+            raster(std::move(m.raster)), rawbytes(std::move(m.rawbytes)) {}
+        Layer& operator=(Layer &&m) {
+            raster = std::move(m.raster); rawbytes = std::move(m.rawbytes);
+            return *this;
+        }
+    };
+
+    // We will save the compressed PNG data into RawBytes type buffers in 
+    // parallel. Later we can write every layer to the disk sequentially.
+    std::vector<Layer> m_layers_rst;
+    Raster::Resolution m_res;
+    Raster::PixelDim m_pxdim;
+    double m_exp_time_s = .0, m_exp_time_first_s = .0;
+    double m_layer_height = .0;
+    RasterOrientation m_o = roPortrait;
+    std::array<bool, 2> m_mirror;
+    
+    double m_gamma;
+
+    double m_used_material = 0.0;
+    int    m_cnt_fade_layers = 0;
+    int    m_cnt_slow_layers = 0;
+    int    m_cnt_fast_layers = 0;
+
+    std::string createIniContent(const std::string& projectname) const;
+    
+    static void flpXY(ClipperLib::Polygon& poly);
+    static void flpXY(ExPolygon& poly);
+
+public:
+
+    SLARasterWriter(const SLAPrinterConfig& cfg, 
+                    const SLAMaterialConfig& mcfg, 
+                    double layer_height);
+
+    SLARasterWriter(const SLARasterWriter& ) = delete;
+    SLARasterWriter& operator=(const SLARasterWriter&) = delete;
+
+    // /////////////////////////////////////////////////////////////////////////
+    // FIXME: the following is needed for MSVC2013 compatibility
+    // /////////////////////////////////////////////////////////////////////////
+
+    // SLARasterWriter(SLARasterWriter&& m) = default;
+    // SLARasterWriter& operator=(SLARasterWriter&&) = default;
+    SLARasterWriter(SLARasterWriter&& m):
+        m_layers_rst(std::move(m.m_layers_rst)),
+        m_res(m.m_res),
+        m_pxdim(m.m_pxdim),
+        m_exp_time_s(m.m_exp_time_s),
+        m_exp_time_first_s(m.m_exp_time_first_s),
+        m_layer_height(m.m_layer_height),
+        m_o(m.m_o),
+        m_mirror(std::move(m.m_mirror)),
+        m_gamma(m.m_gamma),
+        m_used_material(m.m_used_material),
+        m_cnt_fade_layers(m.m_cnt_fade_layers),
+        m_cnt_slow_layers(m.m_cnt_slow_layers),
+        m_cnt_fast_layers(m.m_cnt_fast_layers)
+    {}
+
+    // /////////////////////////////////////////////////////////////////////////
+
+    inline void layers(unsigned cnt) { if(cnt > 0) m_layers_rst.resize(cnt); }
+    inline unsigned layers() const { return unsigned(m_layers_rst.size()); }
+    
+    template<class Poly> void draw_polygon(const Poly& p, unsigned lyr) {
+        assert(lyr < m_layers_rst.size());
+        if(m_o == roPortrait) {
+            Poly poly(p); flpXY(poly);
+            m_layers_rst[lyr].raster.draw(poly);
+        }
+        else m_layers_rst[lyr].raster.draw(p);
+    }
+
+    inline void begin_layer(unsigned lyr) {
+        if(m_layers_rst.size() <= lyr) m_layers_rst.resize(lyr+1);
+        m_layers_rst[lyr].raster.reset(m_res, m_pxdim, m_mirror, m_gamma);
+    }
+
+    inline void begin_layer() {
+        m_layers_rst.emplace_back();
+        m_layers_rst.front().raster.reset(m_res, m_pxdim, m_mirror, m_gamma);
+    }
+
+    inline void finish_layer(unsigned lyr_id) {
+        assert(lyr_id < m_layers_rst.size());
+        m_layers_rst[lyr_id].rawbytes =
+                m_layers_rst[lyr_id].raster.save(Raster::Format::PNG);
+        m_layers_rst[lyr_id].raster.reset();
+    }
+
+    inline void finish_layer() {
+        if(!m_layers_rst.empty()) {
+            m_layers_rst.back().rawbytes =
+                    m_layers_rst.back().raster.save(Raster::Format::PNG);
+            m_layers_rst.back().raster.reset();
+        }
+    }
+
+    void save(const std::string& fpath, const std::string& prjname = "");
+
+    void set_statistics(const std::vector<double> statistics);
+};
+
+} // namespace sla
+} // namespace Slic3r
+
+#endif // SLARASTERWRITER_HPP
diff --git a/src/libslic3r/SLA/SLARotfinder.cpp b/src/libslic3r/SLA/SLARotfinder.cpp
index 1a91041b7..2e64059d6 100644
--- a/src/libslic3r/SLA/SLARotfinder.cpp
+++ b/src/libslic3r/SLA/SLARotfinder.cpp
@@ -44,7 +44,7 @@ std::array<double, 3> find_best_rotation(const ModelObject& modelobj,
     // call the status callback in each iteration but the actual value may be
     // the same for subsequent iterations (status goes from 0 to 100 but
     // iterations can be many more)
-    auto objfunc = [&emesh, &status, &statuscb, max_tries]
+    auto objfunc = [&emesh, &status, &statuscb, &stopcond, max_tries]
             (double rx, double ry, double rz)
     {
         EigenMesh3D& m = emesh;
@@ -91,7 +91,7 @@ std::array<double, 3> find_best_rotation(const ModelObject& modelobj,
         }
 
         // report status
-        statuscb( unsigned(++status * 100.0/max_tries) );
+        if(!stopcond()) statuscb( unsigned(++status * 100.0/max_tries) );
 
         return score;
     };
diff --git a/src/libslic3r/SLA/SLASupportTreeIGL.cpp b/src/libslic3r/SLA/SLASupportTreeIGL.cpp
index 04e6f79c7..4b6498a20 100644
--- a/src/libslic3r/SLA/SLASupportTreeIGL.cpp
+++ b/src/libslic3r/SLA/SLASupportTreeIGL.cpp
@@ -189,19 +189,10 @@ EigenMesh3D::EigenMesh3D(const TriangleMesh& tmesh): m_aabb(new AABBImpl()) {
     V.resize(3*stl.stats.number_of_facets, 3);
     F.resize(stl.stats.number_of_facets, 3);
     for (unsigned int i = 0; i < stl.stats.number_of_facets; ++i) {
-        const stl_facet* facet = stl.facet_start+i;
-        V(3*i+0, 0) = double(facet->vertex[0](0));
-        V(3*i+0, 1) = double(facet->vertex[0](1));
-        V(3*i+0, 2) = double(facet->vertex[0](2));
-
-        V(3*i+1, 0) = double(facet->vertex[1](0));
-        V(3*i+1, 1) = double(facet->vertex[1](1));
-        V(3*i+1, 2) = double(facet->vertex[1](2));
-
-        V(3*i+2, 0) = double(facet->vertex[2](0));
-        V(3*i+2, 1) = double(facet->vertex[2](1));
-        V(3*i+2, 2) = double(facet->vertex[2](2));
-
+        const stl_facet &facet = stl.facet_start[i];
+		V.block<1, 3>(3 * i + 0, 0) = facet.vertex[0].cast<double>();
+		V.block<1, 3>(3 * i + 1, 0) = facet.vertex[1].cast<double>();
+		V.block<1, 3>(3 * i + 2, 0) = facet.vertex[2].cast<double>();
         F(i, 0) = int(3*i+0);
         F(i, 1) = int(3*i+1);
         F(i, 2) = int(3*i+2);
diff --git a/src/libslic3r/Rasterizer/bicubic.h b/src/libslic3r/SLA/bicubic.h
similarity index 100%
rename from src/libslic3r/Rasterizer/bicubic.h
rename to src/libslic3r/SLA/bicubic.h
diff --git a/src/libslic3r/SLAPrint.cpp b/src/libslic3r/SLAPrint.cpp
index 9fe0687b5..789a8120f 100644
--- a/src/libslic3r/SLAPrint.cpp
+++ b/src/libslic3r/SLAPrint.cpp
@@ -783,8 +783,8 @@ void SLAPrint::process()
         {
             // We apply the printer correction offset here.
             if(clpr_offs != 0)
-                po.m_model_slices[id] =
-                    offset_ex(po.m_model_slices[id], float(clpr_offs));
+                po.m_model_slices[id] = 
+                        offset_ex(po.m_model_slices[id], float(clpr_offs));
             
             mit->set_model_slice_idx(po, id); ++mit;
         }
@@ -1085,7 +1085,7 @@ void SLAPrint::process()
         namespace sl = libnest2d::shapelike;    // For algorithms
 
         // If the raster has vertical orientation, we will flip the coordinates
-        bool flpXY = m_printer_config.display_orientation.getInt() == SLADisplayOrientation::sladoPortrait;
+//        bool flpXY = m_printer_config.display_orientation.getInt() == SLADisplayOrientation::sladoPortrait;
 
         // Set up custom union and diff functions for clipper polygons
         auto polyunion = [] (const ClipperPolygons& subjects)
@@ -1143,9 +1143,9 @@ void SLAPrint::process()
 
         // get polygons for all instances in the object
         auto get_all_polygons =
-                [flpXY](const ExPolygons& input_polygons,
-                        const std::vector<SLAPrintObject::Instance>& instances,
-                        bool is_lefthanded)
+                [](const ExPolygons& input_polygons,
+                   const std::vector<SLAPrintObject::Instance>& instances,
+                   bool is_lefthanded)
         {
             ClipperPolygons polygons;
             polygons.reserve(input_polygons.size() * instances.size());
@@ -1159,7 +1159,7 @@ void SLAPrint::process()
 
                     // We need to reverse if flpXY OR is_lefthanded is true but
                     // not if both are true which is a logical inequality (XOR)
-                    bool needreverse = flpXY != is_lefthanded;
+                    bool needreverse = /*flpXY !=*/ is_lefthanded;
 
                     // should be a move
                     poly.Contour.reserve(polygon.contour.size() + 1);
@@ -1194,10 +1194,10 @@ void SLAPrint::process()
                     sl::translate(poly, ClipperPoint{instances[i].shift(X),
                                                      instances[i].shift(Y)});
 
-                    if (flpXY) {
-                        for(auto& p : poly.Contour) std::swap(p.X, p.Y);
-                        for(auto& h : poly.Holes) for(auto& p : h) std::swap(p.X, p.Y);
-                    }
+//                    if (flpXY) {
+//                        for(auto& p : poly.Contour) std::swap(p.X, p.Y);
+//                        for(auto& h : poly.Holes) for(auto& p : h) std::swap(p.X, p.Y);
+//                    }
 
                     polygons.emplace_back(std::move(poly));
                 }
@@ -1366,35 +1366,11 @@ void SLAPrint::process()
     auto rasterize = [this]() {
         if(canceled()) return;
 
-        // collect all the keys
-
-        // If the raster has vertical orientation, we will flip the coordinates
-        bool flpXY = m_printer_config.display_orientation.getInt() ==
-                SLADisplayOrientation::sladoPortrait;
-
         { // create a raster printer for the current print parameters
-            // I don't know any better
-            auto& ocfg = m_objects.front()->m_config;
-            auto& matcfg = m_material_config;
-            auto& printcfg = m_printer_config;
-
-            double w = printcfg.display_width.getFloat();
-            double h = printcfg.display_height.getFloat();
-            auto pw = unsigned(printcfg.display_pixels_x.getInt());
-            auto ph = unsigned(printcfg.display_pixels_y.getInt());
-            double lh = ocfg.layer_height.getFloat();
-            double exp_t = matcfg.exposure_time.getFloat();
-            double iexp_t = matcfg.initial_exposure_time.getFloat();
-            
-            double gamma = m_printer_config.gamma_correction.getFloat();
-
-            if(flpXY) { std::swap(w, h); std::swap(pw, ph); }
-
-            m_printer.reset(
-                new SLAPrinter(w, h, pw, ph, lh, exp_t, iexp_t,
-                               flpXY? SLAPrinter::RO_PORTRAIT : 
-                                      SLAPrinter::RO_LANDSCAPE, 
-                               gamma));
+            double layerh = m_default_object_config.layer_height.getFloat();
+            m_printer.reset(new SLAPrinter(m_printer_config, 
+                                           m_material_config, 
+                                           layerh));
         }
 
         // Allocate space for all the layers
@@ -1582,6 +1558,8 @@ bool SLAPrint::invalidate_state_by_config_options(const std::vector<t_config_opt
         "display_height",
         "display_pixels_x",
         "display_pixels_y",
+        "display_mirror_x",
+        "display_mirror_y",
         "display_orientation"
     };
 
diff --git a/src/libslic3r/SLAPrint.hpp b/src/libslic3r/SLAPrint.hpp
index 0c7d92ff2..b0c5a8fdc 100644
--- a/src/libslic3r/SLAPrint.hpp
+++ b/src/libslic3r/SLAPrint.hpp
@@ -3,11 +3,11 @@
 
 #include <mutex>
 #include "PrintBase.hpp"
-#include "PrintExport.hpp"
+//#include "PrintExport.hpp"
+#include "SLA/SLARasterWriter.hpp"
 #include "Point.hpp"
 #include "MTUtils.hpp"
 #include <libnest2d/backends/clipper/clipper_polygon.hpp>
-#include "Zipper.hpp"
 
 namespace Slic3r {
 
@@ -326,37 +326,6 @@ struct SLAPrintStatistics
     }
 };
 
-// The implementation of creating zipped archives with wxWidgets
-template<> class LayerWriter<Zipper> {
-    Zipper m_zip;
-public:
-
-    LayerWriter(const std::string& zipfile_path): m_zip(zipfile_path) {}
-
-    void next_entry(const std::string& fname) { m_zip.add_entry(fname); }
-
-    void binary_entry(const std::string& fname,
-                      const std::uint8_t* buf,
-                      size_t l)
-    {
-        m_zip.add_entry(fname, buf, l);
-    }
-
-    template<class T> inline LayerWriter& operator<<(T&& arg) {
-        m_zip << std::forward<T>(arg); return *this;
-    }
-
-    bool is_ok() const {
-        return true; // m_zip blows up if something goes wrong...
-    }
-
-    // After finalize, no writing to the archive will have an effect. The only
-    // valid operation is to dispose the object calling the destructor which
-    // should close the file. This method can throw and signal potential errors
-    // when flushing the archive. This is why its present.
-    void finalize() { m_zip.finalize(); }
-};
-
 /**
  * @brief This class is the high level FSM for the SLA printing process.
  *
@@ -389,11 +358,10 @@ public:
     // Returns true if the last step was finished with success.
     bool                finished() const override { return this->is_step_done(slaposSliceSupports) && this->Inherited::is_step_done(slapsRasterize); }
 
-    template<class Fmt = Zipper>
     inline void export_raster(const std::string& fpath,
-                       const std::string& projectname = "")
+                              const std::string& projectname = "")
     {
-        if(m_printer) m_printer->save<Fmt>(fpath, projectname);
+        if(m_printer) m_printer->save(fpath, projectname);
     }
 
     const PrintObjects& objects() const { return m_objects; }
@@ -454,7 +422,7 @@ public:
     const std::vector<PrintLayer>& print_layers() const { return m_printer_input; }
 
 private:
-    using SLAPrinter = FilePrinter<FilePrinterFormat::SLA_PNGZIP>;
+    using SLAPrinter = sla::SLARasterWriter;
     using SLAPrinterPtr = std::unique_ptr<SLAPrinter>;
 
     // Implement same logic as in SLAPrintObject
diff --git a/src/libslic3r/Slicing.cpp b/src/libslic3r/Slicing.cpp
index 3a05e9d8a..e1bb4b313 100644
--- a/src/libslic3r/Slicing.cpp
+++ b/src/libslic3r/Slicing.cpp
@@ -227,7 +227,7 @@ std::vector<coordf_t> layer_height_profile_adaptive(
     as.set_slicing_parameters(slicing_params);
     for (const ModelVolume *volume : volumes)
         if (volume->is_model_part())
-            as.add_mesh(&volume->mesh);
+            as.add_mesh(&volume->mesh());
     as.prepare();
 
     // 2) Generate layers using the algorithm of @platsch 
diff --git a/src/libslic3r/SlicingAdaptive.cpp b/src/libslic3r/SlicingAdaptive.cpp
index 2ef4aec8c..ad03b550b 100644
--- a/src/libslic3r/SlicingAdaptive.cpp
+++ b/src/libslic3r/SlicingAdaptive.cpp
@@ -27,8 +27,8 @@ void SlicingAdaptive::prepare()
 		nfaces_total += (*it_mesh)->stl.stats.number_of_facets;
 	m_faces.reserve(nfaces_total);
 	for (std::vector<const TriangleMesh*>::const_iterator it_mesh = m_meshes.begin(); it_mesh != m_meshes.end(); ++ it_mesh)
-		for (int i = 0; i < (*it_mesh)->stl.stats.number_of_facets; ++ i)
-			m_faces.push_back((*it_mesh)->stl.facet_start + i);
+		for (const stl_facet &face : (*it_mesh)->stl.facet_start)
+			m_faces.emplace_back(&face);
 
 	// 2) Sort faces lexicographically by their Z span.
 	std::sort(m_faces.begin(), m_faces.end(), [](const stl_facet *f1, const stl_facet *f2) {
diff --git a/src/libslic3r/TriangleMesh.cpp b/src/libslic3r/TriangleMesh.cpp
index 6581a8320..56accfefa 100644
--- a/src/libslic3r/TriangleMesh.cpp
+++ b/src/libslic3r/TriangleMesh.cpp
@@ -42,20 +42,17 @@
 
 namespace Slic3r {
 
-TriangleMesh::TriangleMesh(const Pointf3s &points, const std::vector<Vec3crd>& facets)
-    : repaired(false)
+TriangleMesh::TriangleMesh(const Pointf3s &points, const std::vector<Vec3crd>& facets) : repaired(false)
 {
-    stl_initialize(&this->stl);
     stl_file &stl = this->stl;
-    stl.error = 0;
     stl.stats.type = inmemory;
 
     // count facets and allocate memory
-    stl.stats.number_of_facets = facets.size();
+    stl.stats.number_of_facets = (uint32_t)facets.size();
     stl.stats.original_num_facets = stl.stats.number_of_facets;
     stl_allocate(&stl);
 
-    for (uint32_t i = 0; i < stl.stats.number_of_facets; i++) {
+	for (uint32_t i = 0; i < stl.stats.number_of_facets; ++ i) {
         stl_facet facet;
         facet.vertex[0] = points[facets[i](0)].cast<float>();
         facet.vertex[1] = points[facets[i](1)].cast<float>();
@@ -73,57 +70,37 @@ TriangleMesh::TriangleMesh(const Pointf3s &points, const std::vector<Vec3crd>& f
     stl_get_size(&stl);
 }
 
-TriangleMesh& TriangleMesh::operator=(const TriangleMesh &other)
-{
-    stl_close(&this->stl);
-    this->stl       = other.stl;
-    this->repaired  = other.repaired;
-    this->stl.heads = nullptr;
-    this->stl.tail  = nullptr;
-    this->stl.error = other.stl.error;
-    if (other.stl.facet_start != nullptr) {
-        this->stl.facet_start = (stl_facet*)calloc(other.stl.stats.number_of_facets, sizeof(stl_facet));
-        std::copy(other.stl.facet_start, other.stl.facet_start + other.stl.stats.number_of_facets, this->stl.facet_start);
-    }
-    if (other.stl.neighbors_start != nullptr) {
-        this->stl.neighbors_start = (stl_neighbors*)calloc(other.stl.stats.number_of_facets, sizeof(stl_neighbors));
-        std::copy(other.stl.neighbors_start, other.stl.neighbors_start + other.stl.stats.number_of_facets, this->stl.neighbors_start);
-    }
-    if (other.stl.v_indices != nullptr) {
-        this->stl.v_indices = (v_indices_struct*)calloc(other.stl.stats.number_of_facets, sizeof(v_indices_struct));
-        std::copy(other.stl.v_indices, other.stl.v_indices + other.stl.stats.number_of_facets, this->stl.v_indices);
-    }
-    if (other.stl.v_shared != nullptr) {
-        this->stl.v_shared = (stl_vertex*)calloc(other.stl.stats.shared_vertices, sizeof(stl_vertex));
-        std::copy(other.stl.v_shared, other.stl.v_shared + other.stl.stats.shared_vertices, this->stl.v_shared);
-    }
-    return *this;
-}
-
 // #define SLIC3R_TRACE_REPAIR
 
-void TriangleMesh::repair()
+void TriangleMesh::repair(bool update_shared_vertices)
 {
-    if (this->repaired) return;
-    
+    if (this->repaired) {
+    	if (update_shared_vertices)
+    		this->require_shared_vertices();
+    	return;
+    }
+
     // admesh fails when repairing empty meshes
-    if (this->stl.stats.number_of_facets == 0) return;
+    if (this->stl.stats.number_of_facets == 0)
+    	return;
 
     BOOST_LOG_TRIVIAL(debug) << "TriangleMesh::repair() started";
-    
+
     // checking exact
 #ifdef SLIC3R_TRACE_REPAIR
 	BOOST_LOG_TRIVIAL(trace) << "\tstl_check_faces_exact";
 #endif /* SLIC3R_TRACE_REPAIR */
+	assert(stl_validate(&this->stl));
 	stl_check_facets_exact(&stl);
+    assert(stl_validate(&this->stl));
     stl.stats.facets_w_1_bad_edge = (stl.stats.connected_facets_2_edge - stl.stats.connected_facets_3_edge);
     stl.stats.facets_w_2_bad_edge = (stl.stats.connected_facets_1_edge - stl.stats.connected_facets_2_edge);
     stl.stats.facets_w_3_bad_edge = (stl.stats.number_of_facets - stl.stats.connected_facets_1_edge);
     
     // checking nearby
     //int last_edges_fixed = 0;
-	float tolerance = stl.stats.shortest_edge;
-    float increment = stl.stats.bounding_diameter / 10000.0;
+	float tolerance = (float)stl.stats.shortest_edge;
+	float increment = (float)stl.stats.bounding_diameter / 10000.0f;
     int iterations = 2;
     if (stl.stats.connected_facets_3_edge < (int)stl.stats.number_of_facets) {
         for (int i = 0; i < iterations; i++) {
@@ -141,6 +118,7 @@ void TriangleMesh::repair()
             }
         }
     }
+    assert(stl_validate(&this->stl));
     
     // remove_unconnected
     if (stl.stats.connected_facets_3_edge < (int)stl.stats.number_of_facets) {
@@ -148,6 +126,7 @@ void TriangleMesh::repair()
         BOOST_LOG_TRIVIAL(trace) << "\tstl_remove_unconnected_facets";
 #endif /* SLIC3R_TRACE_REPAIR */
         stl_remove_unconnected_facets(&stl);
+	    assert(stl_validate(&this->stl));
     }
     
     // fill_holes
@@ -168,28 +147,38 @@ void TriangleMesh::repair()
     BOOST_LOG_TRIVIAL(trace) << "\tstl_fix_normal_directions";
 #endif /* SLIC3R_TRACE_REPAIR */
     stl_fix_normal_directions(&stl);
+    assert(stl_validate(&this->stl));
 
     // normal_values
 #ifdef SLIC3R_TRACE_REPAIR
     BOOST_LOG_TRIVIAL(trace) << "\tstl_fix_normal_values";
 #endif /* SLIC3R_TRACE_REPAIR */
     stl_fix_normal_values(&stl);
+    assert(stl_validate(&this->stl));
     
     // always calculate the volume and reverse all normals if volume is negative
 #ifdef SLIC3R_TRACE_REPAIR
     BOOST_LOG_TRIVIAL(trace) << "\tstl_calculate_volume";
 #endif /* SLIC3R_TRACE_REPAIR */
     stl_calculate_volume(&stl);
+    assert(stl_validate(&this->stl));
     
     // neighbors
 #ifdef SLIC3R_TRACE_REPAIR
     BOOST_LOG_TRIVIAL(trace) << "\tstl_verify_neighbors";
 #endif /* SLIC3R_TRACE_REPAIR */
     stl_verify_neighbors(&stl);
+    assert(stl_validate(&this->stl));
 
     this->repaired = true;
 
     BOOST_LOG_TRIVIAL(debug) << "TriangleMesh::repair() finished";
+
+    // This call should be quite cheap, a lot of code requires the indexed_triangle_set data structure,
+    // and it is risky to generate such a structure once the meshes are shared. Do it now.
+    this->its.clear();
+    if (update_shared_vertices)
+    	this->require_shared_vertices();
 }
 
 float TriangleMesh::volume()
@@ -249,20 +238,24 @@ bool TriangleMesh::needed_repair() const
 
 void TriangleMesh::WriteOBJFile(const char* output_file)
 {
-    stl_generate_shared_vertices(&stl);
-    stl_write_obj(&stl, output_file);
+    its_write_obj(this->its, output_file);
 }
 
 void TriangleMesh::scale(float factor)
 {
     stl_scale(&(this->stl), factor);
-    stl_invalidate_shared_vertices(&this->stl);
+	for (stl_vertex& v : this->its.vertices)
+		v *= factor;
 }
 
 void TriangleMesh::scale(const Vec3d &versor)
 {
     stl_scale_versor(&this->stl, versor.cast<float>());
-    stl_invalidate_shared_vertices(&this->stl);
+	for (stl_vertex& v : this->its.vertices) {
+		v.x() *= versor.x();
+		v.y() *= versor.y();
+		v.z() *= versor.z();
+	}
 }
 
 void TriangleMesh::translate(float x, float y, float z)
@@ -270,7 +263,9 @@ void TriangleMesh::translate(float x, float y, float z)
     if (x == 0.f && y == 0.f && z == 0.f)
         return;
     stl_translate_relative(&(this->stl), x, y, z);
-    stl_invalidate_shared_vertices(&this->stl);
+	stl_vertex shift(x, y, z);
+	for (stl_vertex& v : this->its.vertices)
+		v += shift;
 }
 
 void TriangleMesh::translate(const Vec3f &displacement)
@@ -287,13 +282,15 @@ void TriangleMesh::rotate(float angle, const Axis &axis)
     angle = Slic3r::Geometry::rad2deg(angle);
     
     if (axis == X) {
-        stl_rotate_x(&(this->stl), angle);
+        stl_rotate_x(&this->stl, angle);
+        its_rotate_x(this->its, angle);
     } else if (axis == Y) {
-        stl_rotate_y(&(this->stl), angle);
+        stl_rotate_y(&this->stl, angle);
+        its_rotate_y(this->its, angle);
     } else if (axis == Z) {
-        stl_rotate_z(&(this->stl), angle);
+        stl_rotate_z(&this->stl, angle);
+        its_rotate_z(this->its, angle);
     }
-    stl_invalidate_shared_vertices(&this->stl);
 }
 
 void TriangleMesh::rotate(float angle, const Vec3d& axis)
@@ -305,39 +302,49 @@ void TriangleMesh::rotate(float angle, const Vec3d& axis)
     Transform3d m = Transform3d::Identity();
     m.rotate(Eigen::AngleAxisd(angle, axis_norm));
     stl_transform(&stl, m);
+    its_transform(its, m);
 }
 
 void TriangleMesh::mirror(const Axis &axis)
 {
     if (axis == X) {
         stl_mirror_yz(&this->stl);
+        for (stl_vertex &v : this->its.vertices)
+      		v(0) *= -1.0;
     } else if (axis == Y) {
         stl_mirror_xz(&this->stl);
+        for (stl_vertex &v : this->its.vertices)
+      		v(1) *= -1.0;
     } else if (axis == Z) {
         stl_mirror_xy(&this->stl);
+        for (stl_vertex &v : this->its.vertices)
+      		v(2) *= -1.0;
     }
-    stl_invalidate_shared_vertices(&this->stl);
 }
 
 void TriangleMesh::transform(const Transform3d& t, bool fix_left_handed)
 {
     stl_transform(&stl, t);
-    stl_invalidate_shared_vertices(&stl);
+    its_transform(its, t);
 	if (fix_left_handed && t.matrix().block(0, 0, 3, 3).determinant() < 0.) {
 		// Left handed transformation is being applied. It is a good idea to flip the faces and their normals.
-		this->repair();
+		this->repair(false);
 		stl_reverse_all_facets(&stl);
+		this->its.clear();
+		this->require_shared_vertices();
 	}
 }
 
 void TriangleMesh::transform(const Matrix3d& m, bool fix_left_handed)
 {
     stl_transform(&stl, m);
-    stl_invalidate_shared_vertices(&stl);
+    its_transform(its, m);
     if (fix_left_handed && m.determinant() < 0.) {
         // Left handed transformation is being applied. It is a good idea to flip the faces and their normals.
-        this->repair();
+        this->repair(false);
         stl_reverse_all_facets(&stl);
+		this->its.clear();
+		this->require_shared_vertices();
     }
 }
 
@@ -355,7 +362,8 @@ void TriangleMesh::rotate(double angle, Point* center)
         return;
     Vec2f c = center->cast<float>();
     this->translate(-c(0), -c(1), 0);
-    stl_rotate_z(&(this->stl), (float)angle);
+    stl_rotate_z(&this->stl, (float)angle);
+    its_rotate_z(this->its, (float)angle);
     this->translate(c(0), c(1), 0);
 }
 
@@ -435,9 +443,8 @@ TriangleMeshPtrs TriangleMesh::split() const
         TriangleMesh* mesh = new TriangleMesh;
         meshes.emplace_back(mesh);
         mesh->stl.stats.type = inmemory;
-        mesh->stl.stats.number_of_facets = facets.size();
+        mesh->stl.stats.number_of_facets = (uint32_t)facets.size();
         mesh->stl.stats.original_num_facets = mesh->stl.stats.number_of_facets;
-        stl_clear_error(&mesh->stl);
         stl_allocate(&mesh->stl);
 
         // Assign the facets to the new mesh.
@@ -455,7 +462,7 @@ void TriangleMesh::merge(const TriangleMesh &mesh)
 {
     // reset stats and metadata
     int number_of_facets = this->stl.stats.number_of_facets;
-    stl_invalidate_shared_vertices(&this->stl);
+    this->its.clear();
     this->repaired = false;
     
     // update facet count and allocate more memory
@@ -477,13 +484,12 @@ ExPolygons TriangleMesh::horizontal_projection() const
 {
     Polygons pp;
     pp.reserve(this->stl.stats.number_of_facets);
-    for (uint32_t i = 0; i < this->stl.stats.number_of_facets; ++ i) {
-        stl_facet* facet = &this->stl.facet_start[i];
+	for (const stl_facet &facet : this->stl.facet_start) {
         Polygon p;
         p.points.resize(3);
-        p.points[0] = Point::new_scale(facet->vertex[0](0), facet->vertex[0](1));
-        p.points[1] = Point::new_scale(facet->vertex[1](0), facet->vertex[1](1));
-        p.points[2] = Point::new_scale(facet->vertex[2](0), facet->vertex[2](1));
+        p.points[0] = Point::new_scale(facet.vertex[0](0), facet.vertex[0](1));
+        p.points[1] = Point::new_scale(facet.vertex[1](0), facet.vertex[1](1));
+        p.points[2] = Point::new_scale(facet.vertex[2](0), facet.vertex[2](1));
         p.make_counter_clockwise();  // do this after scaling, as winding order might change while doing that
         pp.emplace_back(p);
     }
@@ -495,11 +501,10 @@ ExPolygons TriangleMesh::horizontal_projection() const
 // 2D convex hull of a 3D mesh projected into the Z=0 plane.
 Polygon TriangleMesh::convex_hull()
 {
-    this->require_shared_vertices();
     Points pp;
-    pp.reserve(this->stl.stats.shared_vertices);
-    for (int i = 0; i < this->stl.stats.shared_vertices; ++ i) {
-        const stl_vertex &v = this->stl.v_shared[i];
+    pp.reserve(this->its.vertices.size());
+    for (size_t i = 0; i < this->its.vertices.size(); ++ i) {
+        const stl_vertex &v = this->its.vertices[i];
         pp.emplace_back(Point::new_scale(v(0), v(1)));
     }
     return Slic3r::Geometry::convex_hull(pp);
@@ -517,49 +522,47 @@ BoundingBoxf3 TriangleMesh::bounding_box() const
 BoundingBoxf3 TriangleMesh::transformed_bounding_box(const Transform3d &trafo) const
 {
     BoundingBoxf3 bbox;
-    if (stl.v_shared == nullptr) {
+    if (this->its.vertices.empty()) {
         // Using the STL faces.
-        for (size_t i = 0; i < this->facets_count(); ++ i) {
-            const stl_facet &facet = this->stl.facet_start[i];
+		for (const stl_facet &facet : this->stl.facet_start)
             for (size_t j = 0; j < 3; ++ j)
                 bbox.merge(trafo * facet.vertex[j].cast<double>());
-        }
     } else {
         // Using the shared vertices should be a bit quicker than using the STL faces.
-        for (int i = 0; i < stl.stats.shared_vertices; ++ i)            
-            bbox.merge(trafo * this->stl.v_shared[i].cast<double>());
+		for (const stl_vertex &v : this->its.vertices)
+            bbox.merge(trafo * v.cast<double>());
     }
     return bbox;
 }
 
 TriangleMesh TriangleMesh::convex_hull_3d() const
 {
-    // Helper struct for qhull:
-    struct PointForQHull{
-        PointForQHull(float x_p, float y_p, float z_p) : x((realT)x_p), y((realT)y_p), z((realT)z_p) {}
-        realT x, y, z;
-    };
-    std::vector<PointForQHull> src_vertices;
-
-    // We will now fill the vector with input points for computation:
-    stl_facet* facet_ptr = stl.facet_start;
-    while (facet_ptr < stl.facet_start + stl.stats.number_of_facets)
-    {
-        for (int i = 0; i < 3; ++i)
-        {
-            const stl_vertex& v = facet_ptr->vertex[i];
-            src_vertices.emplace_back(v(0), v(1), v(2));
-        }
-
-        facet_ptr += 1;
-    }
-
     // The qhull call:
     orgQhull::Qhull qhull;
     qhull.disableOutputStream(); // we want qhull to be quiet
-    try
+	std::vector<realT> src_vertices;
+	try
     {
-        qhull.runQhull("", 3, (int)src_vertices.size(), (const realT*)(src_vertices.data()), "Qt");
+    	if (this->has_shared_vertices()) {
+#if REALfloat
+	    	qhull.runQhull("", 3, (int)this->its.vertices.size(), (const realT*)(this->its.vertices.front().data()), "Qt");
+#else
+	    	src_vertices.reserve(this->its.vertices() * 3);
+	    	// We will now fill the vector with input points for computation:
+			for (const stl_vertex &v : ths->its.vertices.size())
+				for (int i = 0; i < 3; ++ i)
+		        	src_vertices.emplace_back(v(i));
+	        qhull.runQhull("", 3, (int)src_vertices.size() / 3, src_vertices.data(), "Qt");
+#endif
+	    } else {
+	    	src_vertices.reserve(this->stl.facet_start.size() * 9);
+	    	// We will now fill the vector with input points for computation:
+			for (const stl_facet &f : this->stl.facet_start)
+				for (int i = 0; i < 3; ++ i)
+					for (int j = 0; j < 3; ++ j)
+		        		src_vertices.emplace_back(f.vertex[i](j));
+	        qhull.runQhull("", 3, (int)src_vertices.size() / 3, src_vertices.data(), "Qt");
+	    }
     }
     catch (...)
     {
@@ -587,34 +590,20 @@ TriangleMesh TriangleMesh::convex_hull_3d() const
 
     TriangleMesh output_mesh(dst_vertices, facets);
     output_mesh.repair();
-    output_mesh.require_shared_vertices();
     return output_mesh;
 }
 
 void TriangleMesh::require_shared_vertices()
 {
     BOOST_LOG_TRIVIAL(trace) << "TriangleMeshSlicer::require_shared_vertices - start";
-    if (!this->repaired) 
+    assert(stl_validate(&this->stl));
+    if (! this->repaired) 
         this->repair();
-    if (this->stl.v_shared == NULL) {
+    if (this->its.vertices.empty()) {
         BOOST_LOG_TRIVIAL(trace) << "TriangleMeshSlicer::require_shared_vertices - stl_generate_shared_vertices";
-        stl_generate_shared_vertices(&(this->stl));
+        stl_generate_shared_vertices(&this->stl, this->its);
     }
-#ifdef _DEBUG
-    // Verify validity of neighborship data.
-    for (int facet_idx = 0; facet_idx < stl.stats.number_of_facets; ++facet_idx) {
-        const stl_neighbors &nbr = stl.neighbors_start[facet_idx];
-        const int *vertices = stl.v_indices[facet_idx].vertex;
-        for (int nbr_idx = 0; nbr_idx < 3; ++nbr_idx) {
-            int nbr_face = this->stl.neighbors_start[facet_idx].neighbor[nbr_idx];
-            if (nbr_face != -1) {
-				assert(
-					(stl.v_indices[nbr_face].vertex[(nbr.which_vertex_not[nbr_idx] + 1) % 3] == vertices[(nbr_idx + 1) % 3] && stl.v_indices[nbr_face].vertex[(nbr.which_vertex_not[nbr_idx] + 2) % 3] == vertices[nbr_idx]) ||
-					(stl.v_indices[nbr_face].vertex[(nbr.which_vertex_not[nbr_idx] + 2) % 3] == vertices[(nbr_idx + 1) % 3] && stl.v_indices[nbr_face].vertex[(nbr.which_vertex_not[nbr_idx] + 1) % 3] == vertices[nbr_idx]));
-            }
-        }
-    }
-#endif /* _DEBUG */
+    assert(stl_validate(&this->stl, this->its));
     BOOST_LOG_TRIVIAL(trace) << "TriangleMeshSlicer::require_shared_vertices - end";
 }
 
@@ -626,10 +615,9 @@ void TriangleMeshSlicer::init(const TriangleMesh *_mesh, throw_on_cancel_callbac
 
     throw_on_cancel();
     facets_edges.assign(_mesh->stl.stats.number_of_facets * 3, -1);
-    v_scaled_shared.assign(_mesh->stl.v_shared, _mesh->stl.v_shared + _mesh->stl.stats.shared_vertices);
-    // Scale the copied vertices.
-    for (int i = 0; i < this->mesh->stl.stats.shared_vertices; ++ i)
-        this->v_scaled_shared[i] *= float(1. / SCALING_FACTOR);
+	v_scaled_shared.assign(_mesh->its.vertices.size(), stl_vertex());
+	for (size_t i = 0; i < v_scaled_shared.size(); ++ i)
+        this->v_scaled_shared[i] = _mesh->its.vertices[i] / float(SCALING_FACTOR);
 
     // Create a mapping from triangle edge into face.
     struct EdgeToFace {
@@ -649,8 +637,8 @@ void TriangleMeshSlicer::init(const TriangleMesh *_mesh, throw_on_cancel_callbac
     for (uint32_t facet_idx = 0; facet_idx < this->mesh->stl.stats.number_of_facets; ++ facet_idx)
         for (int i = 0; i < 3; ++ i) {
             EdgeToFace &e2f = edges_map[facet_idx*3+i];
-            e2f.vertex_low  = this->mesh->stl.v_indices[facet_idx].vertex[i];
-            e2f.vertex_high = this->mesh->stl.v_indices[facet_idx].vertex[(i + 1) % 3];
+            e2f.vertex_low  = this->mesh->its.indices[facet_idx][i];
+            e2f.vertex_high = this->mesh->its.indices[facet_idx][(i + 1) % 3];
             e2f.face        = facet_idx;
             // 1 based indexing, to be always strictly positive.
             e2f.face_edge   = i + 1;
@@ -818,7 +806,7 @@ void TriangleMeshSlicer::slice(const std::vector<float> &z, std::vector<Polygons
 void TriangleMeshSlicer::_slice_do(size_t facet_idx, std::vector<IntersectionLines>* lines, boost::mutex* lines_mutex, 
     const std::vector<float> &z) const
 {
-    const stl_facet &facet = m_use_quaternion ? this->mesh->stl.facet_start[facet_idx].rotated(m_quaternion) : this->mesh->stl.facet_start[facet_idx];
+    const stl_facet &facet = m_use_quaternion ? (this->mesh->stl.facet_start.data() + facet_idx)->rotated(m_quaternion) : *(this->mesh->stl.facet_start.data() + facet_idx);
     
     // find facet extents
     const float min_z = fminf(facet.vertex[0](2), fminf(facet.vertex[1](2), facet.vertex[2](2)));
@@ -887,7 +875,7 @@ TriangleMeshSlicer::FacetSliceType TriangleMeshSlicer::slice_facet(
     // Reorder vertices so that the first one is the one with lowest Z.
     // This is needed to get all intersection lines in a consistent order
     // (external on the right of the line)
-    const int *vertices = this->mesh->stl.v_indices[facet_idx].vertex;
+    const stl_triangle_vertex_indices &vertices = this->mesh->its.indices[facet_idx];
     int i = (facet.vertex[1].z() == min_z) ? 1 : ((facet.vertex[2].z() == min_z) ? 2 : 0);
 
     // These are used only if the cut plane is tilted:
@@ -1714,7 +1702,7 @@ void TriangleMeshSlicer::cut(float z, TriangleMesh* upper, TriangleMesh* lower)
     BOOST_LOG_TRIVIAL(trace) << "TriangleMeshSlicer::cut - slicing object";
     float scaled_z = scale_(z);
     for (uint32_t facet_idx = 0; facet_idx < this->mesh->stl.stats.number_of_facets; ++ facet_idx) {
-        stl_facet* facet = &this->mesh->stl.facet_start[facet_idx];
+        const stl_facet* facet = &this->mesh->stl.facet_start[facet_idx];
         
         // find facet extents
         float min_z = std::min(facet->vertex[0](2), std::min(facet->vertex[1](2), facet->vertex[2](2)));
@@ -1736,10 +1724,12 @@ void TriangleMeshSlicer::cut(float z, TriangleMesh* upper, TriangleMesh* lower)
         
         if (min_z > z || (min_z == z && max_z > z)) {
             // facet is above the cut plane and does not belong to it
-            if (upper != NULL) stl_add_facet(&upper->stl, facet);
+            if (upper != nullptr)
+				stl_add_facet(&upper->stl, facet);
         } else if (max_z < z || (max_z == z && min_z < z)) {
             // facet is below the cut plane and does not belong to it
-            if (lower != NULL) stl_add_facet(&lower->stl, facet);
+            if (lower != nullptr)
+				stl_add_facet(&lower->stl, facet);
         } else if (min_z < z && max_z > z) {
             // Facet is cut by the slicing plane.
 
@@ -1786,22 +1776,24 @@ void TriangleMeshSlicer::cut(float z, TriangleMesh* upper, TriangleMesh* lower)
             quadrilateral[1].vertex[2] = v0v1;
             
             if (v0(2) > z) {
-                if (upper != NULL) stl_add_facet(&upper->stl, &triangle);
-                if (lower != NULL) {
+                if (upper != nullptr) 
+					stl_add_facet(&upper->stl, &triangle);
+                if (lower != nullptr) {
                     stl_add_facet(&lower->stl, &quadrilateral[0]);
                     stl_add_facet(&lower->stl, &quadrilateral[1]);
                 }
             } else {
-                if (upper != NULL) {
+                if (upper != nullptr) {
                     stl_add_facet(&upper->stl, &quadrilateral[0]);
                     stl_add_facet(&upper->stl, &quadrilateral[1]);
                 }
-                if (lower != NULL) stl_add_facet(&lower->stl, &triangle);
+                if (lower != nullptr) 
+					stl_add_facet(&lower->stl, &triangle);
             }
         }
     }
     
-    if (upper != NULL) {
+    if (upper != nullptr) {
         BOOST_LOG_TRIVIAL(trace) << "TriangleMeshSlicer::cut - triangulating upper part";
         ExPolygons section;
         this->make_expolygons_simple(upper_lines, &section);
@@ -1815,7 +1807,7 @@ void TriangleMeshSlicer::cut(float z, TriangleMesh* upper, TriangleMesh* lower)
         }
     }
     
-    if (lower != NULL) {
+    if (lower != nullptr) {
         BOOST_LOG_TRIVIAL(trace) << "TriangleMeshSlicer::cut - triangulating lower part";
         ExPolygons section;
         this->make_expolygons_simple(lower_lines, &section);
@@ -1905,10 +1897,10 @@ TriangleMesh make_cylinder(double r, double h, double fa)
 //FIXME better to discretize an Icosahedron recursively http://www.songho.ca/opengl/gl_sphere.html
 TriangleMesh make_sphere(double radius, double fa)
 {
-	int   sectorCount = ceil(2. * M_PI / fa);
-	int   stackCount  = ceil(M_PI / fa);
-	float sectorStep  = 2. * M_PI / sectorCount;
-	float stackStep   = M_PI / stackCount;
+	int   sectorCount = int(ceil(2. * M_PI / fa));
+	int   stackCount  = int(ceil(M_PI / fa));
+	float sectorStep  = float(2. * M_PI / sectorCount);
+	float stackStep   = float(M_PI / stackCount);
 
 	Pointf3s vertices;
 	vertices.reserve((stackCount - 1) * sectorCount + 2);
diff --git a/src/libslic3r/TriangleMesh.hpp b/src/libslic3r/TriangleMesh.hpp
index c284f6482..054a98935 100644
--- a/src/libslic3r/TriangleMesh.hpp
+++ b/src/libslic3r/TriangleMesh.hpp
@@ -21,19 +21,13 @@ typedef std::vector<TriangleMesh*> TriangleMeshPtrs;
 class TriangleMesh
 {
 public:
-    TriangleMesh() : repaired(false) { stl_initialize(&this->stl); }
+    TriangleMesh() : repaired(false) {}
     TriangleMesh(const Pointf3s &points, const std::vector<Vec3crd> &facets);
-    TriangleMesh(const TriangleMesh &other) : repaired(false) { stl_initialize(&this->stl); *this = other; }
-    TriangleMesh(TriangleMesh &&other) : repaired(false) { stl_initialize(&this->stl); this->swap(other); }
-    ~TriangleMesh() { clear(); }
-    TriangleMesh& operator=(const TriangleMesh &other);
-    TriangleMesh& operator=(TriangleMesh &&other) { this->swap(other); return *this; }
-    void clear() { stl_close(&this->stl); this->repaired = false; }
-    void swap(TriangleMesh &other) { std::swap(this->stl, other.stl); std::swap(this->repaired, other.repaired); }
-    void ReadSTLFile(const char* input_file) { stl_open(&stl, input_file); }
-    void write_ascii(const char* output_file) { stl_write_ascii(&this->stl, output_file, ""); }
-    void write_binary(const char* output_file) { stl_write_binary(&this->stl, output_file, ""); }
-    void repair();
+	void clear() { this->stl.clear(); this->its.clear(); this->repaired = false; }
+    bool ReadSTLFile(const char* input_file) { return stl_open(&stl, input_file); }
+    bool write_ascii(const char* output_file) { return stl_write_ascii(&this->stl, output_file, ""); }
+    bool write_binary(const char* output_file) { return stl_write_binary(&this->stl, output_file, ""); }
+    void repair(bool update_shared_vertices = true);
     float volume();
     void check_topology();
     bool is_manifold() const { return this->stl.stats.connected_facets_3_edge == (int)this->stl.stats.number_of_facets; }
@@ -58,7 +52,7 @@ public:
     TriangleMeshPtrs split() const;
     void merge(const TriangleMesh &mesh);
     ExPolygons horizontal_projection() const;
-    const float* first_vertex() const { return this->stl.facet_start ? &this->stl.facet_start->vertex[0](0) : nullptr; }
+    const float* first_vertex() const { return this->stl.facet_start.empty() ? nullptr : &this->stl.facet_start.front().vertex[0](0); }
     // 2D convex hull of a 3D mesh projected into the Z=0 plane.
     Polygon convex_hull();
     BoundingBoxf3 bounding_box() const;
@@ -69,12 +63,13 @@ public:
     void reset_repair_stats();
     bool needed_repair() const;
     void require_shared_vertices();
-    bool   has_shared_vertices() const { return stl.v_shared != NULL; }
+    bool   has_shared_vertices() const { return ! this->its.vertices.empty(); }
     size_t facets_count() const { return this->stl.stats.number_of_facets; }
     bool   empty() const { return this->facets_count() == 0; }
     bool is_splittable() const;
 
     stl_file stl;
+    indexed_triangle_set its;
     bool repaired;
 
 private:
diff --git a/src/slic3r/Config/Version.cpp b/src/slic3r/Config/Version.cpp
index 2eda135d6..fe3adfd7f 100644
--- a/src/slic3r/Config/Version.cpp
+++ b/src/slic3r/Config/Version.cpp
@@ -198,6 +198,11 @@ size_t Index::load(const boost::filesystem::path &path)
     size_t idx_line = 0;
     Version ver;
     while (std::getline(ifs, line)) {
+#ifndef _MSVCVER
+		// On a Unix system, getline does not remove the trailing carriage returns, if the index is shared over a Windows filesystem. Remove them manually.
+		while (! line.empty() && line.back() == '\r')
+			line.pop_back();
+#endif
     	++ idx_line;
     	// Skip the initial white spaces.
     	char *key = left_trim(const_cast<char*>(line.data()));
diff --git a/src/slic3r/GUI/3DScene.cpp b/src/slic3r/GUI/3DScene.cpp
index 59480de1c..33ab1f5d1 100644
--- a/src/slic3r/GUI/3DScene.cpp
+++ b/src/slic3r/GUI/3DScene.cpp
@@ -241,8 +241,6 @@ GLVolume::GLVolume(float r, float g, float b, float a)
     : m_transformed_bounding_box_dirty(true)
     , m_sla_shift_z(0.0)
     , m_transformed_convex_hull_bounding_box_dirty(true)
-    , m_convex_hull(nullptr)
-    , m_convex_hull_owned(false)
     // geometry_id == 0 -> invalid
     , geometry_id(std::pair<size_t, size_t>(0, 0))
     , extruder_id(0)
@@ -268,12 +266,6 @@ GLVolume::GLVolume(float r, float g, float b, float a)
     set_render_color(r, g, b, a);
 }
 
-GLVolume::~GLVolume()
-{
-    if (m_convex_hull_owned)
-        delete m_convex_hull;
-}
-
 void GLVolume::set_render_color(float r, float g, float b, float a)
 {
     render_color[0] = r;
@@ -335,12 +327,6 @@ void GLVolume::set_color_from_model_volume(const ModelVolume *model_volume)
     color[3] = model_volume->is_model_part() ? 1.f : 0.5f;
 }
 
-void GLVolume::set_convex_hull(const TriangleMesh *convex_hull, bool owned)
-{
-    m_convex_hull = convex_hull;
-    m_convex_hull_owned = owned;
-}
-
 Transform3d GLVolume::world_matrix() const
 {
     Transform3d m = m_instance_transformation.get_matrix() * m_volume_transformation.get_matrix();
@@ -377,7 +363,7 @@ const BoundingBoxf3& GLVolume::transformed_convex_hull_bounding_box() const
 
 BoundingBoxf3 GLVolume::transformed_convex_hull_bounding_box(const Transform3d &trafo) const
 {
-	return (m_convex_hull != nullptr && m_convex_hull->stl.stats.number_of_facets > 0) ? 
+	return (m_convex_hull && m_convex_hull->stl.stats.number_of_facets > 0) ? 
 		m_convex_hull->transformed_bounding_box(trafo) :
 		bounding_box.transformed(trafo);
 }
@@ -587,7 +573,7 @@ int GLVolumeCollection::load_object_volume(
     const ModelVolume   *model_volume = model_object->volumes[volume_idx];
     const int            extruder_id  = model_volume->extruder_id();
     const ModelInstance *instance     = model_object->instances[instance_idx];
-    const TriangleMesh& mesh = model_volume->mesh;
+    const TriangleMesh& mesh = model_volume->mesh();
     float color[4];
     memcpy(color, GLVolume::MODEL_COLOR[((color_by == "volume") ? volume_idx : obj_idx) % 4], sizeof(float) * 3);
 /*    if (model_volume->is_support_blocker()) {
@@ -613,7 +599,7 @@ int GLVolumeCollection::load_object_volume(
     if (model_volume->is_model_part())
     {
 		// GLVolume will reference a convex hull from model_volume!
-        v.set_convex_hull(&model_volume->get_convex_hull(), false);
+        v.set_convex_hull(model_volume->get_convex_hull_shared_ptr());
         if (extruder_id != -1)
             v.extruder_id = extruder_id;
     }
@@ -656,7 +642,10 @@ void GLVolumeCollection::load_object_auxiliary(
         v.composite_id = GLVolume::CompositeID(obj_idx, - int(milestone), (int)instance_idx.first);
         v.geometry_id = std::pair<size_t, size_t>(timestamp, model_instance.id().id);
 		// Create a copy of the convex hull mesh for each instance. Use a move operator on the last instance.
-		v.set_convex_hull((&instance_idx == &instances.back()) ? new TriangleMesh(std::move(convex_hull)) : new TriangleMesh(convex_hull), true);
+        if (&instance_idx == &instances.back())
+            v.set_convex_hull(std::move(convex_hull));
+        else
+            v.set_convex_hull(convex_hull);
         v.is_modifier  = false;
         v.shader_outside_printer_detection_enabled = (milestone == slaposSupportTree);
         v.set_instance_transformation(model_instance.get_transformation());
diff --git a/src/slic3r/GUI/3DScene.hpp b/src/slic3r/GUI/3DScene.hpp
index 2ca11073b..0414a1ed3 100644
--- a/src/slic3r/GUI/3DScene.hpp
+++ b/src/slic3r/GUI/3DScene.hpp
@@ -10,6 +10,7 @@
 #include "slic3r/GUI/GLCanvas3DManager.hpp"
 
 #include <functional>
+#include <memory>
 
 #ifndef NDEBUG
 #define HAS_GLSAFE
@@ -243,7 +244,6 @@ public:
 
     GLVolume(float r = 1.f, float g = 1.f, float b = 1.f, float a = 1.f);
     GLVolume(const float *rgba) : GLVolume(rgba[0], rgba[1], rgba[2], rgba[3]) {}
-    ~GLVolume();
 
 private:
     Geometry::Transformation m_instance_transformation;
@@ -255,10 +255,8 @@ private:
     mutable BoundingBoxf3 m_transformed_bounding_box;
     // Whether or not is needed to recalculate the transformed bounding box.
     mutable bool          m_transformed_bounding_box_dirty;
-    // Pointer to convex hull of the original mesh, if any.
-    // This object may or may not own the convex hull instance based on m_convex_hull_owned
-    const TriangleMesh*   m_convex_hull;
-    bool                  m_convex_hull_owned;
+    // Convex hull of the volume, if any.
+    std::shared_ptr<const TriangleMesh> m_convex_hull;
     // Bounding box of this volume, in unscaled coordinates.
     mutable BoundingBoxf3 m_transformed_convex_hull_bounding_box;
     // Whether or not is needed to recalculate the transformed convex hull bounding box.
@@ -395,7 +393,9 @@ public:
     double get_sla_shift_z() const { return m_sla_shift_z; }
     void set_sla_shift_z(double z) { m_sla_shift_z = z; }
 
-    void set_convex_hull(const TriangleMesh *convex_hull, bool owned);
+    void set_convex_hull(std::shared_ptr<const TriangleMesh> convex_hull) { m_convex_hull = std::move(convex_hull); }
+    void set_convex_hull(const TriangleMesh &convex_hull) { m_convex_hull = std::make_shared<const TriangleMesh>(convex_hull); }
+    void set_convex_hull(TriangleMesh &&convex_hull) { m_convex_hull = std::make_shared<const TriangleMesh>(std::move(convex_hull)); }
 
     int                 object_idx() const { return this->composite_id.object_id; }
     int                 volume_idx() const { return this->composite_id.volume_id; }
diff --git a/src/slic3r/GUI/BackgroundSlicingProcess.cpp b/src/slic3r/GUI/BackgroundSlicingProcess.cpp
index 94fb6481b..b77a272e2 100644
--- a/src/slic3r/GUI/BackgroundSlicingProcess.cpp
+++ b/src/slic3r/GUI/BackgroundSlicingProcess.cpp
@@ -89,7 +89,7 @@ void BackgroundSlicingProcess::process_fff()
 	    	// Perform the final post-processing of the export path by applying the print statistics over the file name.
 	    	std::string export_path = m_fff_print->print_statistics().finalize_output_path(m_export_path);
 		    if (copy_file(m_temp_output_path, export_path) != 0)
-	    		throw std::runtime_error(_utf8(L("Copying of the temporary G-code to the output G-code failed")));
+	    		throw std::runtime_error(_utf8(L("Copying of the temporary G-code to the output G-code failed. Maybe the SD card is write locked?")));
 	    	m_print->set_status(95, _utf8(L("Running post-processing scripts")));
 	    	run_post_process_scripts(export_path, m_fff_print->config());
 	    	m_print->set_status(100, (boost::format(_utf8(L("G-code file exported to %1%"))) % export_path).str());
diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index 21f1d23cd..a3e352b98 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -17,6 +17,7 @@
 #include "slic3r/GUI/GUI.hpp"
 #include "slic3r/GUI/PresetBundle.hpp"
 #include "slic3r/GUI/Tab.hpp"
+#include "slic3r/GUI/GUI_Preview.hpp"
 #include "GUI_App.hpp"
 #include "GUI_ObjectList.hpp"
 #include "GUI_ObjectManipulation.hpp"
@@ -1208,6 +1209,8 @@ wxDEFINE_EVENT(EVT_GLCANVAS_MOUSE_DRAGGING_FINISHED, SimpleEvent);
 wxDEFINE_EVENT(EVT_GLCANVAS_UPDATE_BED_SHAPE, SimpleEvent);
 wxDEFINE_EVENT(EVT_GLCANVAS_TAB, SimpleEvent);
 wxDEFINE_EVENT(EVT_GLCANVAS_RESETGIZMOS, SimpleEvent);
+wxDEFINE_EVENT(EVT_GLCANVAS_MOVE_DOUBLE_SLIDER, wxKeyEvent);
+wxDEFINE_EVENT(EVT_GLCANVAS_EDIT_COLOR_CHANGE, wxKeyEvent);
 
 GLCanvas3D::GLCanvas3D(wxGLCanvas* canvas, Bed3D& bed, Camera& camera, GLToolbar& view_toolbar)
     : m_canvas(canvas)
@@ -2386,8 +2389,18 @@ void GLCanvas3D::on_char(wxKeyEvent& evt)
         case '4': { select_view("rear"); break; }
         case '5': { select_view("left"); break; }
         case '6': { select_view("right"); break; }
-        case '+': { post_event(Event<int>(EVT_GLCANVAS_INCREASE_INSTANCES, +1)); break; }
-        case '-': { post_event(Event<int>(EVT_GLCANVAS_INCREASE_INSTANCES, -1)); break; }
+        case '+': { 
+                    if (dynamic_cast<Preview*>(m_canvas->GetParent()) != nullptr)
+                        post_event(wxKeyEvent(EVT_GLCANVAS_EDIT_COLOR_CHANGE, evt)); 
+                    else
+                        post_event(Event<int>(EVT_GLCANVAS_INCREASE_INSTANCES, +1)); 
+                    break; }
+        case '-': {  
+                    if (dynamic_cast<Preview*>(m_canvas->GetParent()) != nullptr)
+                        post_event(wxKeyEvent(EVT_GLCANVAS_EDIT_COLOR_CHANGE, evt)); 
+                    else
+                        post_event(Event<int>(EVT_GLCANVAS_INCREASE_INSTANCES, -1)); 
+                    break; }
         case '?': { post_event(SimpleEvent(EVT_GLCANVAS_QUESTION_MARK)); break; }
         case 'A':
         case 'a': { post_event(SimpleEvent(EVT_GLCANVAS_ARRANGE)); break; }
@@ -2467,6 +2480,15 @@ void GLCanvas3D::on_key(wxKeyEvent& evt)
                 }
                 else if (keyCode == WXK_CONTROL)
                     m_dirty = true;
+                // DoubleSlider navigation in Preview
+                else if (keyCode == WXK_LEFT    || 
+                         keyCode == WXK_RIGHT   ||
+                         keyCode == WXK_UP      || 
+                         keyCode == WXK_DOWN    )
+                {
+                    if (dynamic_cast<Preview*>(m_canvas->GetParent()) != nullptr)
+                        post_event(wxKeyEvent(EVT_GLCANVAS_MOVE_DOUBLE_SLIDER, evt));
+                }
             }
         }
     }
@@ -5502,7 +5524,7 @@ void GLCanvas3D::_load_sla_shells()
         v.set_instance_offset(unscale(instance.shift(0), instance.shift(1), 0));
         v.set_instance_rotation(Vec3d(0.0, 0.0, (double)instance.rotation));
         v.set_instance_mirror(X, object.is_left_handed() ? -1. : 1.);
-        v.set_convex_hull(new TriangleMesh(std::move(mesh.convex_hull_3d())), true);
+        v.set_convex_hull(mesh.convex_hull_3d());
     };
 
     // adds objects' volumes 
diff --git a/src/slic3r/GUI/GLCanvas3D.hpp b/src/slic3r/GUI/GLCanvas3D.hpp
index 51a36cf69..fc7dddd46 100644
--- a/src/slic3r/GUI/GLCanvas3D.hpp
+++ b/src/slic3r/GUI/GLCanvas3D.hpp
@@ -124,6 +124,8 @@ wxDECLARE_EVENT(EVT_GLCANVAS_MOUSE_DRAGGING_FINISHED, SimpleEvent);
 wxDECLARE_EVENT(EVT_GLCANVAS_UPDATE_BED_SHAPE, SimpleEvent);
 wxDECLARE_EVENT(EVT_GLCANVAS_TAB, SimpleEvent);
 wxDECLARE_EVENT(EVT_GLCANVAS_RESETGIZMOS, SimpleEvent);
+wxDECLARE_EVENT(EVT_GLCANVAS_MOVE_DOUBLE_SLIDER, wxKeyEvent);
+wxDECLARE_EVENT(EVT_GLCANVAS_EDIT_COLOR_CHANGE, wxKeyEvent);
 
 class GLCanvas3D
 {
diff --git a/src/slic3r/GUI/GUI_ObjectList.cpp b/src/slic3r/GUI/GUI_ObjectList.cpp
index dffa02e95..a95b71bcb 100644
--- a/src/slic3r/GUI/GUI_ObjectList.cpp
+++ b/src/slic3r/GUI/GUI_ObjectList.cpp
@@ -261,7 +261,7 @@ wxString ObjectList::get_mesh_errors_list(const int obj_idx, const int vol_idx /
 
     const stl_stats& stats = vol_idx == -1 ?
                             (*m_objects)[obj_idx]->get_object_stl_stats() :
-                            (*m_objects)[obj_idx]->volumes[vol_idx]->mesh.stl.stats;
+                            (*m_objects)[obj_idx]->volumes[vol_idx]->mesh().stl.stats;
 
     std::map<std::string, int> error_msg = {
         { L("degenerate facets"),   stats.degenerate_facets },
@@ -1415,13 +1415,18 @@ void ObjectList::update_opt_keys(t_config_option_keys& opt_keys)
 
 void ObjectList::load_subobject(ModelVolumeType type)
 {
-    auto item = GetSelection();
-    if (!item || m_objects_model->GetParent(item) != wxDataViewItem(0))
+    wxDataViewItem item = GetSelection();
+    // we can add volumes for Object or Instance
+    if (!item || !(m_objects_model->GetItemType(item)&(itObject|itInstance)))
         return;
-    int obj_idx = m_objects_model->GetIdByItem(item);
+    const int obj_idx = m_objects_model->GetObjectIdByItem(item);
 
     if (obj_idx < 0) return;
 
+    // Get object item, if Instance is selected
+    if (m_objects_model->GetItemType(item)&itInstance)
+        item = m_objects_model->GetItemById(obj_idx);
+
     std::vector<std::pair<wxString, bool>> volumes_info;
     load_part((*m_objects)[obj_idx], volumes_info, type);
 
@@ -1592,7 +1597,7 @@ void ObjectList::load_generic_subobject(const std::string& type_name, const Mode
         // First (any) GLVolume of the selected instance. They all share the same instance matrix.
         const GLVolume* v = selection.get_volume(*selection.get_volume_idxs().begin());
         // Transform the new modifier to be aligned with the print bed.
-		const BoundingBoxf3 mesh_bb = new_volume->mesh.bounding_box();
+		const BoundingBoxf3 mesh_bb = new_volume->mesh().bounding_box();
 		new_volume->set_transformation(volume_to_bed_transformation(v->get_instance_transformation(), mesh_bb));
         // Set the modifier position.
         auto offset = (type_name == "Slab") ?
@@ -2150,9 +2155,11 @@ void ObjectList::update_selections()
     if (GetSelectedItemsCount() == 1 && m_objects_model->GetItemType(GetSelection()) == itSettings )
     {
         const auto item = GetSelection();
-        if (selection.is_single_full_object() && 
-            m_objects_model->GetIdByItem(m_objects_model->GetParent(item)) == selection.get_object_idx())
-            return; 
+        if (selection.is_single_full_object()) {
+            if ( m_objects_model->GetIdByItem(m_objects_model->GetParent(item)) == selection.get_object_idx())
+                return;
+            sels.Add(m_objects_model->GetItemById(selection.get_object_idx()));
+        }
         if (selection.is_single_volume() || selection.is_any_modifier()) {
             const auto gl_vol = selection.get_volume(*selection.get_volume_idxs().begin());
             if (m_objects_model->GetVolumeIdByItem(m_objects_model->GetParent(item)) == gl_vol->volume_idx())
diff --git a/src/slic3r/GUI/GUI_ObjectManipulation.cpp b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
index 5bf25f3fc..310000ecc 100644
--- a/src/slic3r/GUI/GUI_ObjectManipulation.cpp
+++ b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
@@ -92,6 +92,7 @@ void msw_rescale_word_local_combo(wxBitmapComboBox* combo)
     combo->SetValue(selection);
 }
 
+
 ObjectManipulation::ObjectManipulation(wxWindow* parent) :
     OG_Settings(parent, true)
 #ifndef __APPLE__
@@ -162,16 +163,71 @@ ObjectManipulation::ObjectManipulation(wxWindow* parent) :
 
     const int field_width = 5;
 
+    // Mirror button size:
+    const int mirror_btn_width = 3;
+
     // Legend for object modification
     line = Line{ "", "" };
     def.label = "";
     def.type = coString;
-    def.width = field_width/*50*/;
+    def.width = field_width - mirror_btn_width;//field_width/*50*/;
+
+    // Load bitmaps to be used for the mirroring buttons:
+    m_mirror_bitmap_on  = ScalableBitmap(parent, "mirroring_on.png");
+    m_mirror_bitmap_off = ScalableBitmap(parent, "mirroring_off.png");
+    m_mirror_bitmap_hidden = ScalableBitmap(parent, "mirroring_transparent.png");
 
 	for (const std::string axis : { "x", "y", "z" }) {
         const std::string label = boost::algorithm::to_upper_copy(axis);
         def.set_default_value(new ConfigOptionString{ "   " + label });
         Option option = Option(def, axis + "_axis_legend");
+
+        unsigned int axis_idx = (axis[0] - 'x'); // 0, 1 or 2
+
+        // We will add a button to toggle mirroring to each axis:
+        auto mirror_button = [=](wxWindow* parent) {
+            wxSize btn_size(em_unit(parent) * mirror_btn_width, em_unit(parent) * mirror_btn_width);
+            auto btn = new ScalableButton(parent, wxID_ANY, "mirroring_off.png", wxEmptyString, btn_size, wxDefaultPosition, wxBU_EXACTFIT | wxNO_BORDER | wxTRANSPARENT_WINDOW);
+            btn->SetToolTip(wxString::Format(_(L("Toggle %s axis mirroring")), label));
+
+            m_mirror_buttons[axis_idx].first = btn;
+            m_mirror_buttons[axis_idx].second = mbShown;
+            auto sizer = new wxBoxSizer(wxHORIZONTAL);
+            sizer->Add(btn);
+
+            btn->Bind(wxEVT_BUTTON, [=](wxCommandEvent &e) {
+                Axis axis = (Axis)(axis_idx + X);
+                if (m_mirror_buttons[axis_idx].second == mbHidden)
+                    return;
+
+                GLCanvas3D* canvas = wxGetApp().plater()->canvas3D();
+                Selection& selection = canvas->get_selection();
+
+                if (selection.is_single_volume() || selection.is_single_modifier()) {
+                    GLVolume* volume = const_cast<GLVolume*>(selection.get_volume(*selection.get_volume_idxs().begin()));
+                    volume->set_volume_mirror(axis, -volume->get_volume_mirror(axis));
+                }
+                else if (selection.is_single_full_instance()) {
+                    for (unsigned int idx : selection.get_volume_idxs()){
+                        GLVolume* volume = const_cast<GLVolume*>(selection.get_volume(idx));
+                        volume->set_instance_mirror(axis, -volume->get_instance_mirror(axis));
+                    }
+                }
+                else
+                    return;
+
+                // Update mirroring at the GLVolumes.
+                selection.synchronize_unselected_instances(Selection::SYNC_ROTATION_GENERAL);
+                selection.synchronize_unselected_volumes();
+                // Copy mirroring values from GLVolumes into Model (ModelInstance / ModelVolume), trigger background processing.
+                canvas->do_mirror();
+                canvas->set_as_dirty();
+                UpdateAndShow(true);
+            });
+        return sizer;
+        };
+
+        option.side_widget = mirror_button;
         line.append_option(option);
     }
     line.near_label_widget = [this](wxWindow* parent) {
@@ -190,8 +246,8 @@ ObjectManipulation::ObjectManipulation(wxWindow* parent) :
         def.set_default_value(new ConfigOptionFloat(0.0));
         def.width = field_width/*50*/;
 
-        // Add "uniform scaling" button in front of "Scale" option 
         if (option_name == "Scale") {
+            // Add "uniform scaling" button in front of "Scale" option
             line.near_label_widget = [this](wxWindow* parent) {
                 auto btn = new LockButton(parent, wxID_ANY);
                 btn->Bind(wxEVT_BUTTON, [btn, this](wxCommandEvent &event){
@@ -201,8 +257,59 @@ ObjectManipulation::ObjectManipulation(wxWindow* parent) :
                 m_lock_bnt = btn;
                 return btn;
             };
+            // Add reset scale button
+            auto reset_scale_button = [=](wxWindow* parent) {
+                auto btn = new ScalableButton(parent, wxID_ANY, ScalableBitmap(parent, "undo"));
+                btn->SetToolTip(_(L("Reset scale")));
+                m_reset_scale_button = btn;
+                auto sizer = new wxBoxSizer(wxHORIZONTAL);
+                sizer->Add(btn, wxBU_EXACTFIT);
+                btn->Bind(wxEVT_BUTTON, [=](wxCommandEvent &e) {
+                    change_scale_value(0, 100.);
+                    change_scale_value(1, 100.);
+                    change_scale_value(2, 100.);
+                });
+            return sizer;
+            };
+            line.append_widget(reset_scale_button);
         }
+        else if (option_name == "Rotation") {
+            // Add reset rotation button
+            auto reset_rotation_button = [=](wxWindow* parent) {
+                auto btn = new ScalableButton(parent, wxID_ANY, ScalableBitmap(parent, "undo"));
+                btn->SetToolTip(_(L("Reset rotation")));
+                m_reset_rotation_button = btn;
+                auto sizer = new wxBoxSizer(wxHORIZONTAL);
+                sizer->Add(btn, wxBU_EXACTFIT);
+                btn->Bind(wxEVT_BUTTON, [=](wxCommandEvent &e) {
+                    GLCanvas3D* canvas = wxGetApp().plater()->canvas3D();
+                    Selection& selection = canvas->get_selection();
 
+                    if (selection.is_single_volume() || selection.is_single_modifier()) {
+                        GLVolume* volume = const_cast<GLVolume*>(selection.get_volume(*selection.get_volume_idxs().begin()));
+                        volume->set_volume_rotation(Vec3d::Zero());
+                    }
+                    else if (selection.is_single_full_instance()) {
+                        for (unsigned int idx : selection.get_volume_idxs()){
+                            GLVolume* volume = const_cast<GLVolume*>(selection.get_volume(idx));
+                            volume->set_instance_rotation(Vec3d::Zero());
+                        }
+                    }
+                    else
+                        return;
+
+                    // Update rotation at the GLVolumes.
+                    selection.synchronize_unselected_instances(Selection::SYNC_ROTATION_GENERAL);
+                    selection.synchronize_unselected_volumes();
+                    // Copy rotation values from GLVolumes into Model (ModelInstance / ModelVolume), trigger background processing.
+                    canvas->do_rotate();
+
+                    UpdateAndShow(true);
+                });
+                return sizer;
+            };
+            line.append_widget(reset_rotation_button);
+        }
         // Add empty bmp (Its size have to be equal to PrusaLockButton) in front of "Size" option to label alignment
         else if (option_name == "Size") {
             line.near_label_widget = [this](wxWindow* parent) {
@@ -224,8 +331,8 @@ ObjectManipulation::ObjectManipulation(wxWindow* parent) :
         return line;
     };
 
-
     // Settings table
+    m_og->sidetext_width = 3;
     m_og->append_line(add_og_to_object_settings(L("Position"), L("mm")), &m_move_Label);
     m_og->append_line(add_og_to_object_settings(L("Rotation"), "°"), &m_rotate_Label);
     m_og->append_line(add_og_to_object_settings(L("Scale"), "%"), &m_scale_Label);
@@ -239,6 +346,8 @@ ObjectManipulation::ObjectManipulation(wxWindow* parent) :
         ctrl->msw_rescale();
     };
 }
+ 
+ 
 
 void ObjectManipulation::Show(const bool show)
 {
@@ -408,9 +517,95 @@ void ObjectManipulation::update_if_dirty()
     else
         m_og->disable();
 
+    update_reset_buttons_visibility();
+    update_mirror_buttons_visibility();
+
     m_dirty = false;
 }
 
+
+
+void ObjectManipulation::update_reset_buttons_visibility()
+{
+    GLCanvas3D* canvas = wxGetApp().plater()->canvas3D();
+    if (!canvas)
+        return;
+    const Selection& selection = canvas->get_selection();
+
+    bool show_rotation = false;
+    bool show_scale = false;
+
+    if (selection.is_single_full_instance() || selection.is_single_modifier() || selection.is_single_volume()) {
+        const GLVolume* volume = selection.get_volume(*selection.get_volume_idxs().begin());
+        Vec3d rotation;
+        Vec3d scale;
+
+        if (selection.is_single_full_instance()) {
+            rotation = volume->get_instance_rotation();
+            scale = volume->get_instance_scaling_factor();
+        }
+        else {
+            rotation = volume->get_volume_rotation();
+            scale = volume->get_volume_scaling_factor();
+        }
+        show_rotation = !rotation.isApprox(Vec3d::Zero());
+        show_scale = !scale.isApprox(Vec3d::Ones());
+    }
+
+    wxGetApp().CallAfter([this, show_rotation, show_scale]{
+        m_reset_rotation_button->Show(show_rotation);
+        m_reset_scale_button->Show(show_scale);
+    });
+}
+
+
+
+void ObjectManipulation::update_mirror_buttons_visibility()
+{
+    GLCanvas3D* canvas = wxGetApp().plater()->canvas3D();
+    Selection& selection = canvas->get_selection();
+    std::array<MirrorButtonState, 3> new_states = {mbHidden, mbHidden, mbHidden};
+
+    if (!m_world_coordinates) {
+        if (selection.is_single_full_instance() || selection.is_single_modifier() || selection.is_single_volume()) {
+            const GLVolume* volume = selection.get_volume(*selection.get_volume_idxs().begin());
+            Vec3d mirror;
+
+            if (selection.is_single_full_instance())
+                mirror = volume->get_instance_mirror();
+            else
+                mirror = volume->get_volume_mirror();
+
+            for (unsigned char i=0; i<3; ++i)
+                new_states[i] = (mirror[i] < 0. ? mbActive : mbShown);
+        }
+    }
+    else {
+        // the mirroring buttons should be hidden in world coordinates,
+        // unless we make it actually mirror in world coords.
+    }
+
+    // Hiding the buttons through Hide() always messed up the sizers. As a workaround, the button
+    // is assigned a transparent bitmap. We must of course remember the actual state.
+    wxGetApp().CallAfter([this, new_states]{
+        for (int i=0; i<3; ++i) {
+            if (new_states[i] != m_mirror_buttons[i].second) {
+                const wxBitmap* bmp;
+                switch (new_states[i]) {
+                    case mbHidden : bmp = &m_mirror_bitmap_hidden.bmp(); m_mirror_buttons[i].first->Enable(false); break;
+                    case mbShown  : bmp = &m_mirror_bitmap_off.bmp(); m_mirror_buttons[i].first->Enable(true); break;
+                    case mbActive : bmp = &m_mirror_bitmap_on.bmp(); m_mirror_buttons[i].first->Enable(true); break;
+                }
+                m_mirror_buttons[i].first->SetBitmap(*bmp);
+                m_mirror_buttons[i].second = new_states[i];
+            }
+        }
+    });
+}
+
+
+
+
 #ifndef __APPLE__
 void ObjectManipulation::emulate_kill_focus()
 {
@@ -493,7 +688,7 @@ void ObjectManipulation::change_rotation_value(int axis, double value)
 
     m_cache.rotation = rotation;
 	m_cache.rotation_rounded(axis) = DBL_MAX;
-	this->UpdateAndShow(true);
+    this->UpdateAndShow(true);
 }
 
 void ObjectManipulation::change_scale_value(int axis, double value)
@@ -511,6 +706,7 @@ void ObjectManipulation::change_scale_value(int axis, double value)
 	this->UpdateAndShow(true);
 }
 
+
 void ObjectManipulation::change_size_value(int axis, double value)
 {
     if (std::abs(m_cache.size_rounded(axis) - value) < EPSILON)
@@ -666,6 +862,12 @@ void ObjectManipulation::msw_rescale()
     m_manifold_warning_bmp.msw_rescale();
     m_fix_throught_netfab_bitmap->SetBitmap(m_manifold_warning_bmp.bmp());
 
+    m_mirror_bitmap_on.msw_rescale();
+    m_mirror_bitmap_off.msw_rescale();
+    m_mirror_bitmap_hidden.msw_rescale();
+    m_reset_scale_button->msw_rescale();
+    m_reset_rotation_button->msw_rescale();
+
     get_og()->msw_rescale();
 }
 
diff --git a/src/slic3r/GUI/GUI_ObjectManipulation.hpp b/src/slic3r/GUI/GUI_ObjectManipulation.hpp
index 7c359f3d7..cc2154514 100644
--- a/src/slic3r/GUI/GUI_ObjectManipulation.hpp
+++ b/src/slic3r/GUI/GUI_ObjectManipulation.hpp
@@ -53,6 +53,23 @@ class ObjectManipulation : public OG_Settings
     wxStaticText*   m_scale_Label = nullptr;
     wxStaticText*   m_rotate_Label = nullptr;
 
+    // Non-owning pointers to the reset buttons, so we can hide and show them.
+    ScalableButton* m_reset_scale_button = nullptr;
+    ScalableButton* m_reset_rotation_button = nullptr;
+
+    // Mirroring buttons and their current state
+    enum MirrorButtonState {
+        mbHidden,
+        mbShown,
+        mbActive
+    };
+    std::array<std::pair<ScalableButton*, MirrorButtonState>, 3> m_mirror_buttons;
+
+    // Bitmaps for the mirroring buttons.
+    ScalableBitmap m_mirror_bitmap_on;
+    ScalableBitmap m_mirror_bitmap_off;
+    ScalableBitmap m_mirror_bitmap_hidden;
+
     // Needs to be updated from OnIdle?
     bool            m_dirty = false;
     // Cached labels for the delayed update, not localized!
@@ -111,10 +128,10 @@ private:
     void reset_settings_value();
     void update_settings_value(const Selection& selection);
 
-    // update size values after scale unit changing or "gizmos"
-    void update_size_value(const Vec3d& size);
-    // update rotation value after "gizmos"
-    void update_rotation_value(const Vec3d& rotation);
+    // Show or hide scale/rotation reset buttons if needed
+    void update_reset_buttons_visibility();
+    //Show or hide mirror buttons
+    void update_mirror_buttons_visibility();
 
     // change values 
     void change_position_value(int axis, double value);
diff --git a/src/slic3r/GUI/GUI_Preview.cpp b/src/slic3r/GUI/GUI_Preview.cpp
index d28b921d9..2f5e10962 100644
--- a/src/slic3r/GUI/GUI_Preview.cpp
+++ b/src/slic3r/GUI/GUI_Preview.cpp
@@ -414,6 +414,18 @@ void Preview::msw_rescale()
     refresh_print();
 }
 
+void Preview::move_double_slider(wxKeyEvent& evt)
+{
+    if (m_slider) 
+        m_slider->OnKeyDown(evt);
+}
+
+void Preview::edit_double_slider(wxKeyEvent& evt)
+{
+    if (m_slider) 
+        m_slider->OnChar(evt);
+}
+
 void Preview::bind_event_handlers()
 {
     this->Bind(wxEVT_SIZE, &Preview::on_size, this);
diff --git a/src/slic3r/GUI/GUI_Preview.hpp b/src/slic3r/GUI/GUI_Preview.hpp
index 1838082c3..93038b0e5 100644
--- a/src/slic3r/GUI/GUI_Preview.hpp
+++ b/src/slic3r/GUI/GUI_Preview.hpp
@@ -122,6 +122,8 @@ public:
     void refresh_print();
 
     void msw_rescale();
+    void move_double_slider(wxKeyEvent& evt);
+    void edit_double_slider(wxKeyEvent& evt);
 
 private:
     bool init(wxWindow* parent, Bed3D& bed, Camera& camera, GLToolbar& view_toolbar, Model* model);
diff --git a/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.cpp b/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.cpp
index 72db3a9dd..cfe07a61c 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.cpp
@@ -27,6 +27,7 @@ GLGizmoSlaSupports::GLGizmoSlaSupports(GLCanvas3D& parent, unsigned int sprite_i
     : GLGizmoBase(parent, sprite_id)
 #endif // ENABLE_SVG_ICONS
     , m_quadric(nullptr)
+    , m_its(nullptr)
 {
     m_quadric = ::gluNewQuadric();
     if (m_quadric != nullptr)
@@ -379,36 +380,23 @@ bool GLGizmoSlaSupports::is_point_clipped(const Vec3d& point) const
 bool GLGizmoSlaSupports::is_mesh_update_necessary() const
 {
     return ((m_state == On) && (m_model_object != nullptr) && !m_model_object->instances.empty())
-        && ((m_model_object->id() != m_current_mesh_model_id) || m_V.size()==0);
+        && ((m_model_object->id() != m_current_mesh_model_id) || m_its == nullptr);
 }
 
 void GLGizmoSlaSupports::update_mesh()
 {
     wxBusyCursor wait;
-    Eigen::MatrixXf& V = m_V;
-    Eigen::MatrixXi& F = m_F;
-    // We rely on SLA model object having a single volume,
     // this way we can use that mesh directly.
     // This mesh does not account for the possible Z up SLA offset.
-    m_mesh = &m_model_object->volumes.front()->mesh;
-    const_cast<TriangleMesh*>(m_mesh)->require_shared_vertices(); // TriangleMeshSlicer needs this
-    const stl_file& stl = m_mesh->stl;
-    V.resize(3 * stl.stats.number_of_facets, 3);
-    F.resize(stl.stats.number_of_facets, 3);
-    for (unsigned int i=0; i<stl.stats.number_of_facets; ++i) {
-        const stl_facet* facet = stl.facet_start+i;
-        V(3*i+0, 0) = facet->vertex[0](0); V(3*i+0, 1) = facet->vertex[0](1); V(3*i+0, 2) = facet->vertex[0](2);
-        V(3*i+1, 0) = facet->vertex[1](0); V(3*i+1, 1) = facet->vertex[1](1); V(3*i+1, 2) = facet->vertex[1](2);
-        V(3*i+2, 0) = facet->vertex[2](0); V(3*i+2, 1) = facet->vertex[2](1); V(3*i+2, 2) = facet->vertex[2](2);
-        F(i, 0) = 3*i+0;
-        F(i, 1) = 3*i+1;
-        F(i, 2) = 3*i+2;
-    }
+    m_mesh = &m_model_object->volumes.front()->mesh();
+    m_its = &m_mesh->its;
     m_current_mesh_model_id = m_model_object->id();
     m_editing_mode = false;
 
-    m_AABB = igl::AABB<Eigen::MatrixXf,3>();
-    m_AABB.init(m_V, m_F);
+	m_AABB.deinit();
+    m_AABB.init(
+        MapMatrixXfUnaligned(m_its->vertices.front().data(), m_its->vertices.size(), 3),
+        MapMatrixXiUnaligned(m_its->indices.front().data(), m_its->indices.size(), 3));
 }
 
 // Unprojects the mouse position on the mesh and return the hit point and normal of the facet.
@@ -416,7 +404,7 @@ void GLGizmoSlaSupports::update_mesh()
 std::pair<Vec3f, Vec3f> GLGizmoSlaSupports::unproject_on_mesh(const Vec2d& mouse_pos)
 {
     // if the gizmo doesn't have the V, F structures for igl, calculate them first:
-    if (m_V.size() == 0)
+    if (m_its == nullptr)
         update_mesh();
 
     const Camera& camera = m_parent.get_camera();
@@ -442,7 +430,10 @@ std::pair<Vec3f, Vec3f> GLGizmoSlaSupports::unproject_on_mesh(const Vec2d& mouse
     point1 = inv * point1;
     point2 = inv * point2;
 
-    if (!m_AABB.intersect_ray(m_V, m_F, point1.cast<float>(), (point2-point1).cast<float>(), hits))
+    if (!m_AABB.intersect_ray(
+        MapMatrixXfUnaligned(m_its->vertices.front().data(), m_its->vertices.size(), 3),
+        MapMatrixXiUnaligned(m_its->indices.front().data(), m_its->indices.size(), 3),
+        point1.cast<float>(), (point2-point1).cast<float>(), hits))
         throw std::invalid_argument("unproject_on_mesh(): No intersection found.");
 
     std::sort(hits.begin(), hits.end(), [](const igl::Hit& a, const igl::Hit& b) { return a.t < b.t; });
@@ -457,9 +448,9 @@ std::pair<Vec3f, Vec3f> GLGizmoSlaSupports::unproject_on_mesh(const Vec2d& mouse
         igl::Hit& hit = hits[i];
         int fid = hit.id;   // facet id
         bc = Vec3f(1-hit.u-hit.v, hit.u, hit.v); // barycentric coordinates of the hit
-        a = (m_V.row(m_F(fid, 1)) - m_V.row(m_F(fid, 0)));
-        b = (m_V.row(m_F(fid, 2)) - m_V.row(m_F(fid, 0)));
-        result = bc(0) * m_V.row(m_F(fid, 0)) + bc(1) * m_V.row(m_F(fid, 1)) + bc(2)*m_V.row(m_F(fid, 2));
+        a = (m_its->vertices[m_its->indices[fid](1)] - m_its->vertices[m_its->indices[fid](0)]);
+        b = (m_its->vertices[m_its->indices[fid](2)] - m_its->vertices[m_its->indices[fid](0)]);
+        result = bc(0) * m_its->vertices[m_its->indices[fid](0)] + bc(1) * m_its->vertices[m_its->indices[fid](1)] + bc(2)*m_its->vertices[m_its->indices[fid](2)];
         if (m_clipping_plane_distance == 0.f || !is_point_clipped(result.cast<double>()))
             break;
     }
@@ -564,15 +555,18 @@ bool GLGizmoSlaSupports::gizmo_event(SLAGizmoEventType action, const Vec2d& mous
                     // Cast a ray in the direction of the camera and look for intersection with the mesh:
                     std::vector<igl::Hit> hits;
                     // Offset the start of the ray to the front of the ball + EPSILON to account for numerical inaccuracies.
-                    if (m_AABB.intersect_ray(m_V, m_F, support_point.pos + direction_to_camera_mesh * (support_point.head_front_radius + EPSILON), direction_to_camera_mesh, hits)) {
+                    if (m_AABB.intersect_ray(
+                            MapMatrixXfUnaligned(m_its->vertices.front().data(), m_its->vertices.size(), 3),
+                            MapMatrixXiUnaligned(m_its->indices.front().data(), m_its->indices.size(), 3),
+                            support_point.pos + direction_to_camera_mesh * (support_point.head_front_radius + EPSILON), direction_to_camera_mesh, hits)) {
                         std::sort(hits.begin(), hits.end(), [](const igl::Hit& h1, const igl::Hit& h2) { return h1.t < h2.t; });
 
                         if (m_clipping_plane_distance != 0.f) {
                             // If the closest hit facet normal points in the same direction as the ray,
                             // we are looking through the mesh and should therefore discard the point:
                             int fid = hits.front().id;   // facet id
-                            Vec3f a = (m_V.row(m_F(fid, 1)) - m_V.row(m_F(fid, 0)));
-                            Vec3f b = (m_V.row(m_F(fid, 2)) - m_V.row(m_F(fid, 0)));
+                            Vec3f a = (m_its->vertices[m_its->indices[fid](1)] - m_its->vertices[m_its->indices[fid](0)]);
+                            Vec3f b = (m_its->vertices[m_its->indices[fid](2)] - m_its->vertices[m_its->indices[fid](0)]);
                             if ((a.cross(b)).dot(direction_to_camera_mesh) > 0.f)
                                 is_obscured = true;
 
@@ -582,7 +576,7 @@ bool GLGizmoSlaSupports::gizmo_event(SLAGizmoEventType action, const Vec2d& mous
                                 int fid = hit.id;   // facet id
 
                                 Vec3f bc = Vec3f(1-hit.u-hit.v, hit.u, hit.v); // barycentric coordinates of the hit
-                                Vec3f hit_pos = bc(0) * m_V.row(m_F(fid, 0)) + bc(1) * m_V.row(m_F(fid, 1)) + bc(2)*m_V.row(m_F(fid, 2));
+                                Vec3f hit_pos = bc(0) * m_its->vertices[m_its->indices[fid](0)] + bc(1) * m_its->vertices[m_its->indices[fid](1)] + bc(2)*m_its->vertices[m_its->indices[fid](2)];
                                 if (is_point_clipped(hit_pos.cast<double>())) {
                                     hits.erase(hits.begin()+j);
                                     --j;
@@ -759,9 +753,12 @@ void GLGizmoSlaSupports::update_cache_entry_normal(unsigned int i) const
     int idx = 0;
     Eigen::Matrix<float, 1, 3> pp = m_editing_mode_cache[i].support_point.pos;
     Eigen::Matrix<float, 1, 3> cc;
-    m_AABB.squared_distance(m_V, m_F, pp, idx, cc);
-    Vec3f a = (m_V.row(m_F(idx, 1)) - m_V.row(m_F(idx, 0)));
-    Vec3f b = (m_V.row(m_F(idx, 2)) - m_V.row(m_F(idx, 0)));
+    m_AABB.squared_distance(
+        MapMatrixXfUnaligned(m_its->vertices.front().data(), m_its->vertices.size(), 3),
+        MapMatrixXiUnaligned(m_its->indices.front().data(), m_its->indices.size(), 3),
+        pp, idx, cc);
+    Vec3f a = (m_its->vertices[m_its->indices[idx](1)] - m_its->vertices[m_its->indices[idx](0)]);
+    Vec3f b = (m_its->vertices[m_its->indices[idx](2)] - m_its->vertices[m_its->indices[idx](0)]);
     m_editing_mode_cache[i].normal = a.cross(b);
 }
 
@@ -1067,8 +1064,7 @@ void GLGizmoSlaSupports::on_set_state()
                 m_clipping_plane_distance = 0.f;
                 // Release triangle mesh slicer and the AABB spatial search structure.
                 m_AABB.deinit();
-				m_V = Eigen::MatrixXf();
-				m_F = Eigen::MatrixXi();
+                m_its = nullptr;
                 m_tms.reset();
                 m_supports_tms.reset();
             });
diff --git a/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.hpp b/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.hpp
index fb758d240..30238cc9d 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.hpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.hpp
@@ -35,10 +35,11 @@ private:
     const float RenderPointScale = 1.f;
 
     GLUquadricObj* m_quadric;
-    Eigen::MatrixXf m_V; // vertices
-    Eigen::MatrixXi m_F; // facets indices
-    igl::AABB<Eigen::MatrixXf,3> m_AABB;
+    typedef Eigen::Map<const Eigen::Matrix<float, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor | Eigen::DontAlign>> MapMatrixXfUnaligned;
+    typedef Eigen::Map<const Eigen::Matrix<int, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor | Eigen::DontAlign>> MapMatrixXiUnaligned;
+    igl::AABB<MapMatrixXfUnaligned, 3> m_AABB;
     const TriangleMesh* m_mesh;
+    const indexed_triangle_set* m_its;
     mutable const TriangleMesh* m_supports_mesh;
     mutable std::vector<Vec2f> m_triangles;
     mutable std::vector<Vec2f> m_supports_triangles;
@@ -131,6 +132,11 @@ private:
 
 protected:
     void on_set_state() override;
+    virtual void on_set_hover_id()
+    {
+        if ((int)m_editing_mode_cache.size() <= m_hover_id)
+            m_hover_id = -1;
+    }
     void on_start_dragging(const Selection& selection) override;
     virtual void on_render_input_window(float x, float y, float bottom_limit, const Selection& selection) override;
 
diff --git a/src/slic3r/GUI/MainFrame.cpp b/src/slic3r/GUI/MainFrame.cpp
index 7e5b3ec05..667dcd899 100644
--- a/src/slic3r/GUI/MainFrame.cpp
+++ b/src/slic3r/GUI/MainFrame.cpp
@@ -54,7 +54,7 @@ DPIFrame(NULL, wxID_ANY, "", wxDefaultPosition, wxDefaultSize, wxDEFAULT_FRAME_S
 #endif // _WIN32
 
 	// initialize status bar
-	m_statusbar = new ProgressStatusBar(this);
+	m_statusbar.reset(new ProgressStatusBar(this));
 	m_statusbar->embed(this);
     m_statusbar->set_status_text(_(L("Version")) + " " +
 		SLIC3R_VERSION +
@@ -103,6 +103,8 @@ DPIFrame(NULL, wxID_ANY, "", wxDefaultPosition, wxDefaultSize, wxDEFAULT_FRAME_S
             event.Veto();
             return;
         }
+        
+        if(m_plater) m_plater->stop_jobs();
 
         // Weird things happen as the Paint messages are floating around the windows being destructed.
         // Avoid the Paint messages by hiding the main window.
@@ -138,6 +140,8 @@ DPIFrame(NULL, wxID_ANY, "", wxDefaultPosition, wxDefaultSize, wxDEFAULT_FRAME_S
     update_ui_from_settings();    // FIXME (?)
 }
 
+MainFrame::~MainFrame() = default;
+
 void MainFrame::update_title()
 {
     wxString title = wxEmptyString;
diff --git a/src/slic3r/GUI/MainFrame.hpp b/src/slic3r/GUI/MainFrame.hpp
index a5de94738..805b663bb 100644
--- a/src/slic3r/GUI/MainFrame.hpp
+++ b/src/slic3r/GUI/MainFrame.hpp
@@ -89,7 +89,7 @@ protected:
 
 public:
     MainFrame();
-    ~MainFrame() {}
+    ~MainFrame();
 
     Plater*     plater() { return m_plater; }
 
@@ -126,7 +126,7 @@ public:
     Plater*             m_plater { nullptr };
     wxNotebook*         m_tabpanel { nullptr };
     wxProgressDialog*   m_progress_dialog { nullptr };
-    ProgressStatusBar*  m_statusbar { nullptr };
+    std::unique_ptr<ProgressStatusBar>  m_statusbar;
 };
 
 } // GUI
diff --git a/src/slic3r/GUI/OptionsGroup.cpp b/src/slic3r/GUI/OptionsGroup.cpp
index 2ac6b00af..014932900 100644
--- a/src/slic3r/GUI/OptionsGroup.cpp
+++ b/src/slic3r/GUI/OptionsGroup.cpp
@@ -276,7 +276,7 @@ void OptionsGroup::append_line(const Line& line, wxStaticText**	full_Label/* = n
 		// add sidetext if any
 		if (option.sidetext != "") {
 			auto sidetext = new wxStaticText(	this->ctrl_parent(), wxID_ANY, _(option.sidetext), wxDefaultPosition, 
-												/*wxSize(sidetext_width*wxGetApp().em_unit(), -1)*/wxDefaultSize, wxALIGN_LEFT);
+												wxSize(sidetext_width != -1 ? sidetext_width*wxGetApp().em_unit() : -1, -1) /*wxDefaultSize*/, wxALIGN_LEFT);
 			sidetext->SetBackgroundStyle(wxBG_STYLE_PAINT);
             sidetext->SetFont(wxGetApp().normal_font());
 			sizer_tmp->Add(sidetext, 0, wxLEFT | wxALIGN_CENTER_VERTICAL, 4);
diff --git a/src/slic3r/GUI/Plater.cpp b/src/slic3r/GUI/Plater.cpp
index 44f77b3f7..f8385c0b5 100644
--- a/src/slic3r/GUI/Plater.cpp
+++ b/src/slic3r/GUI/Plater.cpp
@@ -5,9 +5,11 @@
 #include <vector>
 #include <string>
 #include <regex>
+#include <future>
 #include <boost/algorithm/string.hpp>
 #include <boost/optional.hpp>
 #include <boost/filesystem/path.hpp>
+#include <boost/log/trivial.hpp>
 
 #include <wx/sizer.h>
 #include <wx/stattext.h>
@@ -37,7 +39,12 @@
 #include "libslic3r/SLA/SLARotfinder.hpp"
 #include "libslic3r/Utils.hpp"
 
-#include "libnest2d/optimizers/nlopt/genetic.hpp"
+//#include "libslic3r/ClipperUtils.hpp"
+
+// #include "libnest2d/optimizers/nlopt/genetic.hpp"
+// #include "libnest2d/backends/clipper/geometries.hpp"
+// #include "libnest2d/utils/rotcalipers.hpp"
+#include "libslic3r/MinAreaBoundingBox.hpp"
 
 #include "GUI.hpp"
 #include "GUI_App.hpp"
@@ -1253,8 +1260,243 @@ struct Plater::priv
     Preview *preview;
 
     BackgroundSlicingProcess    background_process;
-    bool                        arranging;
-    bool                        rotoptimizing;
+    
+    // A class to handle UI jobs like arranging and optimizing rotation.
+    // These are not instant jobs, the user has to be informed about their
+    // state in the status progress indicator. On the other hand they are 
+    // separated from the background slicing process. Ideally, these jobs should
+    // run when the background process is not running.
+    //
+    // TODO: A mechanism would be useful for blocking the plater interactions:
+    // objects would be frozen for the user. In case of arrange, an animation
+    // could be shown, or with the optimize orientations, partial results
+    // could be displayed.
+    class Job: public wxEvtHandler {
+        int m_range = 100;
+        std::future<void> m_ftr;
+        priv *m_plater = nullptr;
+        std::atomic<bool> m_running {false}, m_canceled {false};
+        bool m_finalized = false;
+        
+        void run() { 
+            m_running.store(true); process(); m_running.store(false); 
+            
+            // ensure to call the last status to finalize the job
+            update_status(status_range(), "");
+        }
+        
+    protected:
+        
+        // status range for a particular job
+        virtual int status_range() const { return 100; }
+        
+        // status update, to be used from the work thread (process() method)
+        void update_status(int st, const wxString& msg = "") { 
+            auto evt = new wxThreadEvent(); evt->SetInt(st); evt->SetString(msg);
+            wxQueueEvent(this, evt); 
+        }
+        
+        priv& plater() { return *m_plater; }
+        bool was_canceled() const { return m_canceled.load(); }
+        
+        // Launched just before start(), a job can use it to prepare internals
+        virtual void prepare() {}
+        
+        // Launched when the job is finished. It refreshes the 3dscene by def.
+        virtual void finalize() {
+            // Do a full refresh of scene tree, including regenerating
+            // all the GLVolumes. FIXME The update function shall just
+            // reload the modified matrices.
+            if(! was_canceled())
+                plater().update(true);
+        }
+        
+    public:
+        
+        Job(priv *_plater): m_plater(_plater)
+        {
+            Bind(wxEVT_THREAD, [this](const wxThreadEvent& evt){
+                auto msg = evt.GetString();
+                if(! msg.empty()) plater().statusbar()->set_status_text(msg);
+                
+                if(m_finalized) return;
+                
+                plater().statusbar()->set_progress(evt.GetInt());
+                if(evt.GetInt() == status_range()) {
+                    
+                    // set back the original range and cancel callback
+                    plater().statusbar()->set_range(m_range);
+                    plater().statusbar()->set_cancel_callback();
+                    wxEndBusyCursor();
+                    
+                    finalize();
+                    
+                    // dont do finalization again for the same process
+                    m_finalized = true;
+                }
+            });
+        }
+        
+        // TODO: use this when we all migrated to VS2019
+        // Job(const Job&) = delete;
+        // Job(Job&&) = default;
+        // Job& operator=(const Job&) = delete;
+        // Job& operator=(Job&&) = default;
+        Job(const Job&) = delete;
+        Job& operator=(const Job&) = delete;
+        Job(Job &&o) :
+            m_range(o.m_range),
+            m_ftr(std::move(o.m_ftr)),
+            m_plater(o.m_plater),
+            m_finalized(o.m_finalized)
+        {
+            m_running.store(o.m_running.load());
+            m_canceled.store(o.m_canceled.load());
+        }
+        
+        virtual void process() = 0;
+        
+        void start() { // Start the job. No effect if the job is already running
+            if(! m_running.load()) {
+                
+                prepare();                
+                
+                // Save the current status indicatior range and push the new one
+                m_range = plater().statusbar()->get_range();
+                plater().statusbar()->set_range(status_range());
+                
+                // init cancellation flag and set the cancel callback
+                m_canceled.store(false);
+                plater().statusbar()->set_cancel_callback( [this](){ 
+                    m_canceled.store(true);
+                });
+                
+                m_finalized = false;
+                
+                // Changing cursor to busy
+                wxBeginBusyCursor();
+                
+                try {   // Execute the job
+                    m_ftr = std::async(std::launch::async, &Job::run, this);
+                } catch(std::exception& ) { 
+                    update_status(status_range(), 
+                    _(L("ERROR: not enough resources to execute a new job.")));
+                }
+                
+                // The state changes will be undone when the process hits the
+                // last status value, in the status update handler (see ctor)
+            }
+        }
+        
+        // To wait for the running job and join the threads. False is returned
+        // if the timeout has been reached and the job is still running. Call
+        // cancel() before this fn if you want to explicitly end the job.
+        bool join(int timeout_ms = 0) const { 
+            if(!m_ftr.valid()) return true;
+            
+            if(timeout_ms <= 0) 
+                m_ftr.wait();
+            else if(m_ftr.wait_for(std::chrono::milliseconds(timeout_ms)) == 
+                    std::future_status::timeout) 
+                return false;
+            
+            return true;
+        }
+        
+        bool is_running() const { return m_running.load(); }
+        void cancel() { m_canceled.store(true); }
+    };
+    
+    enum class Jobs : size_t {
+        Arrange,
+        Rotoptimize
+    };
+    
+    // Jobs defined inside the group class will be managed so that only one can
+    // run at a time. Also, the background process will be stopped if a job is
+    // started.
+    class ExclusiveJobGroup {
+        
+        static const int ABORT_WAIT_MAX_MS = 10000;
+        
+        priv * m_plater;
+
+        class ArrangeJob : public Job
+        {
+            int count = 0;
+
+        protected:
+            void prepare() override
+            {
+                count = 0;
+                for (auto obj : plater().model.objects)
+                    count += int(obj->instances.size());
+            }
+
+        public:
+            //using Job::Job;
+            ArrangeJob(priv * pltr): Job(pltr) {}
+            int  status_range() const override { return count; }
+            void set_count(int c) { count = c; }
+            void process() override;
+        } arrange_job/*{m_plater}*/;
+
+        class RotoptimizeJob : public Job
+        {
+        public:
+            //using Job::Job;
+            RotoptimizeJob(priv * pltr): Job(pltr) {}
+            void process() override;
+        } rotoptimize_job/*{m_plater}*/;
+
+        // To create a new job, just define a new subclass of Job, implement
+        // the process and the optional prepare() and finalize() methods
+        // Register the instance of the class in the m_jobs container
+        // if it cannot run concurrently with other jobs in this group 
+
+        std::vector<std::reference_wrapper<Job>> m_jobs/*{arrange_job,
+                                                        rotoptimize_job}*/;
+
+    public:
+        ExclusiveJobGroup(priv *_plater)
+            : m_plater(_plater)
+            , arrange_job(m_plater)
+            , rotoptimize_job(m_plater)
+            , m_jobs({arrange_job, rotoptimize_job})
+        {}
+
+        void start(Jobs jid) {
+            m_plater->background_process.stop();
+            stop_all();
+            m_jobs[size_t(jid)].get().start();
+        }
+        
+        void cancel_all() { for (Job& j : m_jobs) j.cancel(); }
+
+        void join_all(int wait_ms = 0)
+        {
+            std::vector<bool> aborted(m_jobs.size(), false);
+            
+            for (size_t jid = 0; jid < m_jobs.size(); ++jid)
+                aborted[jid] = m_jobs[jid].get().join(wait_ms);
+
+            if (!all_of(aborted))
+                BOOST_LOG_TRIVIAL(error) << "Could not abort a job!";
+        }
+        
+        void stop_all() { cancel_all(); join_all(ABORT_WAIT_MAX_MS); }
+        
+        const Job& get(Jobs jobid) const { return m_jobs[size_t(jobid)]; }
+
+        bool is_any_running() const
+        {
+            return std::any_of(m_jobs.begin(),
+                               m_jobs.end(),
+                               [](const Job &j) { return j.is_running(); });
+        }
+        
+    } m_ui_jobs{this};
+
     bool                        delayed_scene_refresh;
     std::string                 delayed_error_message;
 
@@ -1429,8 +1671,6 @@ Plater::priv::priv(Plater *q, MainFrame *main_frame)
 {
 	this->q->SetFont(Slic3r::GUI::wxGetApp().normal_font());
 
-    arranging = false;
-    rotoptimizing = false;
     background_process.set_fff_print(&fff_print);
 	background_process.set_sla_print(&sla_print);
     background_process.set_gcode_preview_data(&gcode_preview_data);
@@ -1517,6 +1757,8 @@ Plater::priv::priv(Plater *q, MainFrame *main_frame)
     preview->get_wxglcanvas()->Bind(EVT_GLCANVAS_QUESTION_MARK, [this](SimpleEvent&) { wxGetApp().keyboard_shortcuts(); });
     preview->get_wxglcanvas()->Bind(EVT_GLCANVAS_UPDATE_BED_SHAPE, [this](SimpleEvent&) { set_bed_shape(config->option<ConfigOptionPoints>("bed_shape")->values); });
     preview->get_wxglcanvas()->Bind(EVT_GLCANVAS_TAB, [this](SimpleEvent&) { select_next_view_3D(); });
+    preview->get_wxglcanvas()->Bind(EVT_GLCANVAS_MOVE_DOUBLE_SLIDER, [this](wxKeyEvent& evt) { preview->move_double_slider(evt); });
+    preview->get_wxglcanvas()->Bind(EVT_GLCANVAS_EDIT_COLOR_CHANGE, [this](wxKeyEvent& evt) { preview->edit_double_slider(evt); });
 
     q->Bind(EVT_SLICING_COMPLETED, &priv::on_slicing_completed, this);
     q->Bind(EVT_PROCESS_COMPLETED, &priv::on_process_completed, this);
@@ -1534,7 +1776,8 @@ Plater::priv::priv(Plater *q, MainFrame *main_frame)
 
 void Plater::priv::update(bool force_full_scene_refresh)
 {
-    wxWindowUpdateLocker freeze_guard(q);
+    // the following line, when enabled, causes flickering on NVIDIA graphics cards
+//    wxWindowUpdateLocker freeze_guard(q);
     if (get_config("autocenter") == "1") {
         // auto *bed_shape_opt = config->opt<ConfigOptionPoints>("bed_shape");
         // const auto bed_shape = Slic3r::Polygon::new_scale(bed_shape_opt->values);
@@ -1604,7 +1847,7 @@ void Plater::priv::update_ui_from_settings()
 
 ProgressStatusBar* Plater::priv::statusbar()
 {
-    return main_frame->m_statusbar;
+    return main_frame->m_statusbar.get();
 }
 
 std::string Plater::priv::get_config(const std::string &key) const
@@ -1670,6 +1913,22 @@ std::vector<size_t> Plater::priv::load_files(const std::vector<fs::path>& input_
                     if (load_config && !config_loaded.empty()) {
                         // Based on the printer technology field found in the loaded config, select the base for the config,
 					    PrinterTechnology printer_technology = Preset::printer_technology(config_loaded);
+
+                        // We can't to load SLA project if there is at least one multi-part object on the bed
+                        if (printer_technology == ptSLA)
+                        {
+                            const ModelObjectPtrs& objects = q->model().objects;
+                            for (auto object : objects)
+                                if (object->volumes.size() > 1)
+                                {
+                                    Slic3r::GUI::show_info(nullptr,
+                                        _(L("You can't to load SLA project if there is at least one multi-part object on the bed")) + "\n\n" +
+                                        _(L("Please check your object list before preset changing.")),
+                                        _(L("Attention!")));
+                                    return obj_idxs;
+                                }
+                        }
+
 					    config.apply(printer_technology == ptFFF ?
                             static_cast<const ConfigBase&>(FullPrintConfig::defaults()) : 
                             static_cast<const ConfigBase&>(SLAFullPrintConfig::defaults()));
@@ -2125,59 +2384,45 @@ void Plater::priv::mirror(Axis axis)
 
 void Plater::priv::arrange()
 {
-    if (arranging) { return; }
-    arranging = true;
-    Slic3r::ScopeGuard arranging_guard([this]() { arranging = false; });
+    m_ui_jobs.start(Jobs::Arrange);
+}
 
-    wxBusyCursor wait;
+// This method will find an optimal orientation for the currently selected item
+// Very similar in nature to the arrange method above...
+void Plater::priv::sla_optimize_rotation() {
+    m_ui_jobs.start(Jobs::Rotoptimize);
+}
 
-    this->background_process.stop();
+void Plater::priv::ExclusiveJobGroup::ArrangeJob::process() {
+    // TODO: we should decide whether to allow arrange when the search is
+    // running we should probably disable explicit slicing and background
+    // processing
 
-    unsigned count = 0;
-    for(auto obj : model.objects) count += obj->instances.size();
+    static const auto arrangestr = _(L("Arranging"));
 
-    auto prev_range = statusbar()->get_range();
-    statusbar()->set_range(count);
-
-    auto statusfn = [this, count] (unsigned st, const std::string& msg) {
-        /* // In case we would run the arrange asynchronously
-        wxCommandEvent event(EVT_PROGRESS_BAR);
-        event.SetInt(st);
-        event.SetString(msg);
-        wxQueueEvent(this->q, event.Clone()); */
-        statusbar()->set_progress(count - st);
-        statusbar()->set_status_text(_(msg));
-
-        // ok, this is dangerous, but we are protected by the flag
-        // 'arranging' and the arrange button is also disabled.
-        // This call is needed for the cancel button to work.
-        wxYieldIfNeeded();
-    };
-
-    statusbar()->set_cancel_callback([this, statusfn](){
-        arranging = false;
-        statusfn(0, L("Arranging canceled"));
-    });
-
-    static const std::string arrangestr = L("Arranging");
+    auto &config = plater().config;
+    auto &view3D = plater().view3D;
+    auto &model  = plater().model;
 
     // FIXME: I don't know how to obtain the minimum distance, it depends
     // on printer technology. I guess the following should work but it crashes.
-    double dist = 6; //PrintConfig::min_object_distance(config);
-    if(printer_technology == ptFFF) {
+    double dist = 6; // PrintConfig::min_object_distance(config);
+    if (plater().printer_technology == ptFFF) {
         dist = PrintConfig::min_object_distance(config);
     }
 
-    auto min_obj_distance = coord_t(dist/SCALING_FACTOR);
+    auto min_obj_distance = coord_t(dist / SCALING_FACTOR);
 
-    const auto *bed_shape_opt = config->opt<ConfigOptionPoints>("bed_shape");
+    const auto *bed_shape_opt = config->opt<ConfigOptionPoints>(
+        "bed_shape");
 
     assert(bed_shape_opt);
-    auto& bedpoints = bed_shape_opt->values;
-    Polyline bed; bed.points.reserve(bedpoints.size());
-    for(auto& v : bedpoints) bed.append(Point::new_scale(v(0), v(1)));
+    auto &   bedpoints = bed_shape_opt->values;
+    Polyline bed;
+    bed.points.reserve(bedpoints.size());
+    for (auto &v : bedpoints) bed.append(Point::new_scale(v(0), v(1)));
 
-    statusfn(0, arrangestr);
+    update_status(0, arrangestr);
 
     arr::WipeTowerInfo wti = view3D->get_canvas3d()->get_wipe_tower_info();
 
@@ -2193,129 +2438,87 @@ void Plater::priv::arrange()
                      bed,
                      hint,
                      false, // create many piles not just one pile
-                     [statusfn](unsigned st) { statusfn(st, arrangestr); },
-                     [this] () { return !arranging; });
-    } catch(std::exception& /*e*/) {
-        GUI::show_error(this->q, L("Could not arrange model objects! "
-                                   "Some geometries may be invalid."));
+                     [this](unsigned st) {
+                         if (st > 0)
+                             update_status(count - int(st), arrangestr);
+                     },
+                     [this]() { return was_canceled(); });
+    } catch (std::exception & /*e*/) {
+        GUI::show_error(plater().q,
+                        L("Could not arrange model objects! "
+                          "Some geometries may be invalid."));
     }
 
+    update_status(count,
+                  was_canceled() ? _(L("Arranging canceled."))
+                                 : _(L("Arranging done.")));
+
     // it remains to move the wipe tower:
     view3D->get_canvas3d()->arrange_wipe_tower(wti);
-
-    statusfn(0, L("Arranging done."));
-    statusbar()->set_range(prev_range);
-    statusbar()->set_cancel_callback(); // remove cancel button
-
-    // Do a full refresh of scene tree, including regenerating all the GLVolumes.
-    //FIXME The update function shall just reload the modified matrices.
-    update(true);
 }
 
-// This method will find an optimal orientation for the currently selected item
-// Very similar in nature to the arrange method above...
-void Plater::priv::sla_optimize_rotation() {
-
-    // TODO: we should decide whether to allow arrange when the search is
-    // running we should probably disable explicit slicing and background
-    // processing
-
-    if (rotoptimizing) { return; }
-    rotoptimizing = true;
-    Slic3r::ScopeGuard rotoptimizing_guard([this]() { rotoptimizing = false; });
-
-    int obj_idx = get_selected_object_idx();
+void Plater::priv::ExclusiveJobGroup::RotoptimizeJob::process()
+{
+    int obj_idx = plater().get_selected_object_idx();
     if (obj_idx < 0) { return; }
 
-    ModelObject * o = model.objects[size_t(obj_idx)];
-
-    background_process.stop();
-
-    auto prev_range = statusbar()->get_range();
-    statusbar()->set_range(100);
-
-    auto stfn = [this] (unsigned st, const std::string& msg) {
-        statusbar()->set_progress(int(st));
-        statusbar()->set_status_text(msg);
-
-        // could be problematic, but we need the cancel button.
-        wxYieldIfNeeded();
-    };
-
-    statusbar()->set_cancel_callback([this, stfn](){
-        rotoptimizing = false;
-        stfn(0, L("Orientation search canceled"));
-    });
+    ModelObject *o = plater().model.objects[size_t(obj_idx)];
 
     auto r = sla::find_best_rotation(
-                *o, .005f,
-                [stfn](unsigned s) { stfn(s, L("Searching for optimal orientation")); },
-                [this](){ return !rotoptimizing; }
-    );
+        *o,
+        .005f,
+        [this](unsigned s) {
+            if (s < 100)
+                update_status(int(s),
+                              _(L("Searching for optimal orientation")));
+        },
+        [this]() { return was_canceled(); });
 
-    const auto *bed_shape_opt = config->opt<ConfigOptionPoints>("bed_shape");
+    const auto *bed_shape_opt =
+        plater().config->opt<ConfigOptionPoints>("bed_shape");
+    
     assert(bed_shape_opt);
 
-    auto& bedpoints = bed_shape_opt->values;
-    Polyline bed; bed.points.reserve(bedpoints.size());
-    for(auto& v : bedpoints) bed.append(Point::new_scale(v(0), v(1)));
+    auto &   bedpoints = bed_shape_opt->values;
+    Polyline bed;
+    bed.points.reserve(bedpoints.size());
+    for (auto &v : bedpoints) bed.append(Point::new_scale(v(0), v(1)));
 
     double mindist = 6.0; // FIXME
-    double offs = mindist / 2.0 - EPSILON;
-
-    if(rotoptimizing) // wasn't canceled
-    for(ModelInstance * oi : o->instances) {
-        oi->set_rotation({r[X], r[Y], r[Z]});
-
-        auto trchull = o->convex_hull_2d(oi->get_transformation().get_matrix());
-
-        namespace opt = libnest2d::opt;
-        opt::StopCriteria stopcr;
-        stopcr.relative_score_difference = 0.01;
-        stopcr.max_iterations = 10000;
-        stopcr.stop_score = 0.0;
-        opt::GeneticOptimizer solver(stopcr);
-        Polygon pbed(bed);
-
-        auto bin = pbed.bounding_box();
-        double binw = bin.size()(X) * SCALING_FACTOR - offs;
-        double binh = bin.size()(Y) * SCALING_FACTOR - offs;
-
-        auto result = solver.optimize_min([&trchull, binw, binh](double rot){
-            auto chull = trchull;
-            chull.rotate(rot);
-
-            auto bb = chull.bounding_box();
-            double bbw = bb.size()(X) * SCALING_FACTOR;
-            double bbh = bb.size()(Y) * SCALING_FACTOR;
-
-            auto wdiff = bbw - binw;
-            auto hdiff = bbh - binh;
-            double diff = 0;
-            if(wdiff < 0 && hdiff < 0) diff = wdiff + hdiff;
-            if(wdiff > 0) diff += wdiff;
-            if(hdiff > 0) diff += hdiff;
-
-            return diff;
-        }, opt::initvals(0.0), opt::bound(-PI/2, PI/2));
-
-        double r = std::get<0>(result.optimum);
-
-        Vec3d rt = oi->get_rotation(); rt(Z) += r;
-        oi->set_rotation(rt);
+    
+    if (!was_canceled()) {
+        for(ModelInstance * oi : o->instances) {
+            oi->set_rotation({r[X], r[Y], r[Z]});
+    
+            auto    trmatrix = oi->get_transformation().get_matrix();
+            Polygon trchull  = o->convex_hull_2d(trmatrix);
+            
+            MinAreaBoundigBox rotbb(trchull, MinAreaBoundigBox::pcConvex);
+            double            r = rotbb.angle_to_X();
+    
+            // The box should be landscape
+            if(rotbb.width() < rotbb.height()) r += PI / 2;
+            
+            Vec3d rt = oi->get_rotation(); rt(Z) += r;
+            
+            oi->set_rotation(rt);
+        }
+    
+        arr::WipeTowerInfo wti; // useless in SLA context
+        arr::find_new_position(plater().model,
+                               o->instances,
+                               coord_t(mindist / SCALING_FACTOR),
+                               bed,
+                               wti);
+    
+        // Correct the z offset of the object which was corrupted be
+        // the rotation
+        o->ensure_on_bed();
     }
 
-    arr::WipeTowerInfo wti; // useless in SLA context
-    arr::find_new_position(model, o->instances, coord_t(mindist/SCALING_FACTOR), bed, wti);
-
-    // Correct the z offset of the object which was corrupted be the rotation
-    o->ensure_on_bed();
-
-    stfn(0, L("Orientation found."));
-    statusbar()->set_range(prev_range);
-    statusbar()->set_cancel_callback();
-
-    update(true);
+    update_status(100,
+                  was_canceled() ? _(L("Orientation search canceled."))
+                                 : _(L("Orientation found.")));
 }
 
 void Plater::priv::split_object()
@@ -2496,7 +2699,7 @@ unsigned int Plater::priv::update_background_process(bool force_validation)
 // Restart background processing thread based on a bitmask of UpdateBackgroundProcessReturnState.
 bool Plater::priv::restart_background_process(unsigned int state)
 {
-    if (arranging || rotoptimizing) {
+    if (m_ui_jobs.is_any_running()) {
         // Avoid a race condition
         return false;
     }
@@ -2727,7 +2930,7 @@ void Plater::priv::on_select_preset(wxCommandEvent &evt)
 void Plater::priv::on_slicing_update(SlicingStatusEvent &evt)
 {
     if (evt.status.percent >= -1) {
-        if (arranging || rotoptimizing) {
+        if (m_ui_jobs.is_any_running()) {
             // Avoid a race condition
             return;
         }
@@ -3208,7 +3411,7 @@ bool Plater::priv::can_fix_through_netfabb() const
 
 bool Plater::priv::can_increase_instances() const
 {
-    if (arranging || rotoptimizing) {
+    if (m_ui_jobs.is_any_running()) {
         return false;
     }
 
@@ -3218,7 +3421,7 @@ bool Plater::priv::can_increase_instances() const
 
 bool Plater::priv::can_decrease_instances() const
 {
-    if (arranging || rotoptimizing) {
+    if (m_ui_jobs.is_any_running()) {
         return false;
     }
 
@@ -3238,7 +3441,7 @@ bool Plater::priv::can_split_to_volumes() const
 
 bool Plater::priv::can_arrange() const
 {
-    return !model.objects.empty() && !arranging;
+    return !model.objects.empty() && !m_ui_jobs.is_any_running();
 }
 
 bool Plater::priv::can_layers_editing() const
@@ -3305,6 +3508,7 @@ SLAPrint&       Plater::sla_print()         { return p->sla_print; }
 
 void Plater::new_project()
 {
+    p->select_view_3D("3D");
     wxPostEvent(p->view3D->get_wxglcanvas(), SimpleEvent(EVT_GLTOOLBAR_DELETE_ALL));
 }
 
@@ -3365,6 +3569,8 @@ void Plater::load_files(const std::vector<std::string>& input_files, bool load_m
 
 void Plater::update() { p->update(); }
 
+void Plater::stop_jobs() { p->m_ui_jobs.stop_all(); }
+
 void Plater::update_ui_from_settings() { p->update_ui_from_settings(); }
 
 void Plater::select_view(const std::string& direction) { p->select_view(direction); }
@@ -3565,7 +3771,7 @@ void Plater::export_stl(bool extended, bool selection_only)
         else
         {
             const GLVolume* volume = selection.get_volume(*selection.get_volume_idxs().begin());
-            mesh = model_object->volumes[volume->volume_idx()]->mesh;
+            mesh = model_object->volumes[volume->volume_idx()]->mesh();
             mesh.transform(volume->get_volume_transformation().get_matrix());
             mesh.translate(-model_object->origin_translation.cast<float>());
         }
@@ -3671,7 +3877,7 @@ void Plater::export_3mf(const boost::filesystem::path& output_path)
     if (!path.Lower().EndsWith(".3mf"))
         return;
 
-	DynamicPrintConfig cfg = wxGetApp().preset_bundle->full_config_secure();
+    DynamicPrintConfig cfg = wxGetApp().preset_bundle->full_config_secure();
     const std::string path_u8 = into_u8(path);
     wxBusyCursor wait;
     if (Slic3r::store_3mf(path_u8.c_str(), &p->model, export_config ? &cfg : nullptr)) {
@@ -3687,6 +3893,9 @@ void Plater::export_3mf(const boost::filesystem::path& output_path)
 
 void Plater::reslice()
 {
+    // Stop arrange and (or) optimize rotation tasks.
+    this->stop_jobs();
+    
     //FIXME Don't reslice if export of G-code or sending to OctoPrint is running.
     // bitmask of UpdateBackgroundProcessReturnState
     unsigned int state = this->p->update_background_process(true);
@@ -3722,7 +3931,7 @@ void Plater::reslice_SLA_supports(const ModelObject &object)
     if (state & priv::UPDATE_BACKGROUND_PROCESS_REFRESH_SCENE)
         this->p->view3D->reload_scene(false);
 
-	if (this->p->background_process.empty() || (state & priv::UPDATE_BACKGROUND_PROCESS_INVALID))
+    if (this->p->background_process.empty() || (state & priv::UPDATE_BACKGROUND_PROCESS_INVALID))
         // Nothing to do on empty input or invalid configuration.
         return;
 
diff --git a/src/slic3r/GUI/Plater.hpp b/src/slic3r/GUI/Plater.hpp
index 16c9cbe64..761bf7a05 100644
--- a/src/slic3r/GUI/Plater.hpp
+++ b/src/slic3r/GUI/Plater.hpp
@@ -144,6 +144,7 @@ public:
     void load_files(const std::vector<std::string>& input_files, bool load_model = true, bool load_config = true);
 
     void update();
+    void stop_jobs();
     void select_view(const std::string& direction);
     void select_view_3D(const std::string& name);
 
diff --git a/src/slic3r/GUI/Preset.cpp b/src/slic3r/GUI/Preset.cpp
index 4b4597033..203800997 100644
--- a/src/slic3r/GUI/Preset.cpp
+++ b/src/slic3r/GUI/Preset.cpp
@@ -514,6 +514,7 @@ const std::vector<std::string>& Preset::sla_printer_options()
             "printer_technology",
             "bed_shape", "max_print_height",
             "display_width", "display_height", "display_pixels_x", "display_pixels_y",
+            "display_mirror_x", "display_mirror_y",
             "display_orientation",
             "fast_tilt_time", "slow_tilt_time", "area_fill",
             "relative_correction",
diff --git a/src/slic3r/GUI/PresetBundle.cpp b/src/slic3r/GUI/PresetBundle.cpp
index fb3b6f7a4..b28cb2eda 100644
--- a/src/slic3r/GUI/PresetBundle.cpp
+++ b/src/slic3r/GUI/PresetBundle.cpp
@@ -781,7 +781,7 @@ void PresetBundle::load_config_file_config(const std::string &name_or_path, bool
                     if (i == 0)
                         suffix[0] = 0;
                     else
-                        sprintf(suffix, "%d", i);
+                        sprintf(suffix, "%d", (int)i);
                     std::string new_name = name + suffix;
                     loaded = &this->filaments.load_preset(this->filaments.path_from_name(new_name),
                         new_name, std::move(cfg), i == 0);
@@ -837,7 +837,7 @@ void PresetBundle::load_config_file_config_bundle(const std::string &path, const
                     return preset_name_dst;
                 // Try to generate another name.
                 char buf[64];
-                sprintf(buf, " (%d)", i);
+                sprintf(buf, " (%d)", (int)i);
                 preset_name_dst = preset_name_src + buf + bundle_name;
             }
         }
@@ -1379,7 +1379,7 @@ void PresetBundle::export_configbundle(const std::string &path, bool export_syst
     for (size_t i = 0; i < this->filament_presets.size(); ++ i) {
         char suffix[64];
         if (i > 0)
-            sprintf(suffix, "_%d", i);
+            sprintf(suffix, "_%d", (int)i);
         else
             suffix[0] = 0;
         c << "filament" << suffix << " = " << this->filament_presets[i] << std::endl;
diff --git a/src/slic3r/GUI/ProgressStatusBar.cpp b/src/slic3r/GUI/ProgressStatusBar.cpp
index b48c5732b..f848e663d 100644
--- a/src/slic3r/GUI/ProgressStatusBar.cpp
+++ b/src/slic3r/GUI/ProgressStatusBar.cpp
@@ -168,6 +168,11 @@ void ProgressStatusBar::set_status_text(const char *txt)
     this->set_status_text(wxString::FromUTF8(txt));
 }
 
+wxString ProgressStatusBar::get_status_text() const
+{
+    return self->GetStatusText();
+}
+
 void ProgressStatusBar::show_cancel_button()
 {
     if(m_cancelbutton) m_cancelbutton->Show();
diff --git a/src/slic3r/GUI/ProgressStatusBar.hpp b/src/slic3r/GUI/ProgressStatusBar.hpp
index 8c6596475..7d624af90 100644
--- a/src/slic3r/GUI/ProgressStatusBar.hpp
+++ b/src/slic3r/GUI/ProgressStatusBar.hpp
@@ -52,6 +52,7 @@ public:
     void        set_status_text(const wxString& txt);
     void        set_status_text(const std::string& txt);
     void        set_status_text(const char *txt);
+    wxString    get_status_text() const;
 
     // Temporary methods to satisfy Perl side
     void        show_cancel_button();
diff --git a/src/slic3r/GUI/Selection.hpp b/src/slic3r/GUI/Selection.hpp
index 54bf52706..5da1e477b 100644
--- a/src/slic3r/GUI/Selection.hpp
+++ b/src/slic3r/GUI/Selection.hpp
@@ -333,6 +333,8 @@ private:
     void render_sidebar_rotation_hint(Axis axis) const;
     void render_sidebar_scale_hint(Axis axis) const;
     void render_sidebar_size_hint(Axis axis, double length) const;
+
+public:
     enum SyncRotationType {
         // Do not synchronize rotation. Either not rotating at all, or rotating by world Z axis.
         SYNC_ROTATION_NONE = 0,
@@ -343,6 +345,8 @@ private:
     };
     void synchronize_unselected_instances(SyncRotationType sync_rotation_type);
     void synchronize_unselected_volumes();
+
+private:
     void ensure_on_bed();
     bool is_from_fully_selected_instance(unsigned int volume_idx) const;
 
diff --git a/src/slic3r/GUI/Tab.cpp b/src/slic3r/GUI/Tab.cpp
index 562d17460..df9c89e57 100644
--- a/src/slic3r/GUI/Tab.cpp
+++ b/src/slic3r/GUI/Tab.cpp
@@ -2087,6 +2087,10 @@ void TabPrinter::build_sla()
     line.append_option(optgroup->get_option("display_pixels_y"));
     optgroup->append_line(line);
     optgroup->append_single_option_line("display_orientation");
+    
+    // FIXME: This should be on one line in the UI
+    optgroup->append_single_option_line("display_mirror_x");
+    optgroup->append_single_option_line("display_mirror_y");
 
     optgroup = page->new_optgroup(_(L("Tilt")));
     line = { _(L("Tilt time")), "" };
diff --git a/src/slic3r/GUI/wxExtensions.cpp b/src/slic3r/GUI/wxExtensions.cpp
index 76ba853dc..7b7178a82 100644
--- a/src/slic3r/GUI/wxExtensions.cpp
+++ b/src/slic3r/GUI/wxExtensions.cpp
@@ -586,7 +586,7 @@ wxDataViewItem ObjectDataViewModel::AddVolumeChild( const wxDataViewItem &parent
 		ItemAdded(parent_item, child);
 
         root->m_volumes_cnt++;
-        if (insert_position > 0) insert_position++;
+        if (insert_position >= 0) insert_position++;
 	}
 
     const auto node = new ObjectDataViewModelNode(root, name, GetVolumeIcon(volume_type, has_errors), extruder_str, root->m_volumes_cnt);
@@ -1587,6 +1587,7 @@ DoubleSlider::DoubleSlider( wxWindow *parent,
 
     // slider events
     Bind(wxEVT_PAINT,       &DoubleSlider::OnPaint,    this);
+    Bind(wxEVT_CHAR,        &DoubleSlider::OnChar,     this);
     Bind(wxEVT_LEFT_DOWN,   &DoubleSlider::OnLeftDown, this);
     Bind(wxEVT_MOTION,      &DoubleSlider::OnMotion,   this);
     Bind(wxEVT_LEFT_UP,     &DoubleSlider::OnLeftUp,   this);
@@ -2366,9 +2367,9 @@ void DoubleSlider::OnWheel(wxMouseEvent& event)
 void DoubleSlider::OnKeyDown(wxKeyEvent &event)
 {
     const int key = event.GetKeyCode();
-    if (key == '+' || key == WXK_NUMPAD_ADD)
+    if (key == WXK_NUMPAD_ADD)
         action_tick(taAdd);
-    else if (key == '-' || key == 390 || key == WXK_DELETE || key == WXK_BACK)
+    else if (key == 390 || key == WXK_DELETE || key == WXK_BACK)
         action_tick(taDel);
     else if (is_horizontal())
     {
@@ -2387,6 +2388,8 @@ void DoubleSlider::OnKeyDown(wxKeyEvent &event)
         else if (key == WXK_UP || key == WXK_DOWN)
             move_current_thumb(key == WXK_UP);
     }
+
+    event.Skip(); // !Needed to have EVT_CHAR generated as well
 }
 
 void DoubleSlider::OnKeyUp(wxKeyEvent &event)
@@ -2398,6 +2401,15 @@ void DoubleSlider::OnKeyUp(wxKeyEvent &event)
     event.Skip();
 }
 
+void DoubleSlider::OnChar(wxKeyEvent& event)
+{
+    const int key = event.GetKeyCode();
+    if (key == '+')
+        action_tick(taAdd);
+    else if (key == '-')
+        action_tick(taDel);
+}
+
 void DoubleSlider::OnRightDown(wxMouseEvent& event)
 {
     this->CaptureMouse();
diff --git a/src/slic3r/GUI/wxExtensions.hpp b/src/slic3r/GUI/wxExtensions.hpp
index 78fb7be55..c496c28a0 100644
--- a/src/slic3r/GUI/wxExtensions.hpp
+++ b/src/slic3r/GUI/wxExtensions.hpp
@@ -727,6 +727,7 @@ public:
     void OnWheel(wxMouseEvent& event);
     void OnKeyDown(wxKeyEvent &event);
     void OnKeyUp(wxKeyEvent &event);
+    void OnChar(wxKeyEvent &event);
     void OnRightDown(wxMouseEvent& event);
     void OnRightUp(wxMouseEvent& event);
 
diff --git a/src/slic3r/Utils/FixModelByWin10.cpp b/src/slic3r/Utils/FixModelByWin10.cpp
index 1daeaff26..710f19090 100644
--- a/src/slic3r/Utils/FixModelByWin10.cpp
+++ b/src/slic3r/Utils/FixModelByWin10.cpp
@@ -389,10 +389,10 @@ void fix_model_by_win10_sdk_gui(ModelObject &model_object, int volume_idx)
 	 				throw std::runtime_error(L("Repaired 3MF file does not contain any volume"));
 				if (model.objects.front()->volumes.size() > 1)
 	 				throw std::runtime_error(L("Repaired 3MF file contains more than one volume"));
-	 			meshes_repaired.emplace_back(std::move(model.objects.front()->volumes.front()->mesh));
+	 			meshes_repaired.emplace_back(std::move(model.objects.front()->volumes.front()->mesh()));
 			}
 			for (size_t i = 0; i < volumes.size(); ++ i) {
-				volumes[i]->mesh = std::move(meshes_repaired[i]);
+				volumes[i]->set_mesh(std::move(meshes_repaired[i]));
 				volumes[i]->set_new_unique_id();
 			}
 			model_object.invalidate_bounding_box();
diff --git a/xs/xsp/Model.xsp b/xs/xsp/Model.xsp
index a1c8890ef..6a2cc6080 100644
--- a/xs/xsp/Model.xsp
+++ b/xs/xsp/Model.xsp
@@ -253,7 +253,7 @@ ModelMaterial::attributes()
     Ref<DynamicPrintConfig> config()
         %code%{ RETVAL = &THIS->config; %};
     Ref<TriangleMesh> mesh()
-        %code%{ RETVAL = &THIS->mesh; %};
+        %code%{ RETVAL = &THIS->mesh(); %};
     
     bool modifier()
         %code%{ RETVAL = THIS->is_modifier(); %};
diff --git a/xs/xsp/TriangleMesh.xsp b/xs/xsp/TriangleMesh.xsp
index e519f9210..f3153665c 100644
--- a/xs/xsp/TriangleMesh.xsp
+++ b/xs/xsp/TriangleMesh.xsp
@@ -46,7 +46,6 @@ TriangleMesh::ReadFromPerl(vertices, facets)
     SV* facets
     CODE:
         stl_file &stl = THIS->stl;
-        stl.error = 0;
         stl.stats.type = inmemory;
     
         // count facets and allocate memory
@@ -99,20 +98,18 @@ SV*
 TriangleMesh::vertices()
     CODE:
         if (!THIS->repaired) CONFESS("vertices() requires repair()");
-        
-        if (THIS->stl.v_shared == NULL)
-            stl_generate_shared_vertices(&(THIS->stl));
+        THIS->require_shared_vertices();
         
         // vertices
         AV* vertices = newAV();
-        av_extend(vertices, THIS->stl.stats.shared_vertices);
-        for (int i = 0; i < THIS->stl.stats.shared_vertices; i++) {
+        av_extend(vertices, THIS->its.vertices.size());
+        for (size_t i = 0; i < THIS->its.vertices.size(); i++) {
             AV* vertex = newAV();
             av_store(vertices, i, newRV_noinc((SV*)vertex));
             av_extend(vertex, 2);
-            av_store(vertex, 0, newSVnv(THIS->stl.v_shared[i](0)));
-            av_store(vertex, 1, newSVnv(THIS->stl.v_shared[i](1)));
-            av_store(vertex, 2, newSVnv(THIS->stl.v_shared[i](2)));
+            av_store(vertex, 0, newSVnv(THIS->its.vertices[i](0)));
+            av_store(vertex, 1, newSVnv(THIS->its.vertices[i](1)));
+            av_store(vertex, 2, newSVnv(THIS->its.vertices[i](2)));
         }
         
         RETVAL = newRV_noinc((SV*)vertices);
@@ -123,9 +120,7 @@ SV*
 TriangleMesh::facets()
     CODE:
         if (!THIS->repaired) CONFESS("facets() requires repair()");
-        
-        if (THIS->stl.v_shared == NULL)
-            stl_generate_shared_vertices(&(THIS->stl));
+        THIS->require_shared_vertices();
         
         // facets
         AV* facets = newAV();
@@ -134,9 +129,9 @@ TriangleMesh::facets()
             AV* facet = newAV();
             av_store(facets, i, newRV_noinc((SV*)facet));
             av_extend(facet, 2);
-            av_store(facet, 0, newSVnv(THIS->stl.v_indices[i].vertex[0]));
-            av_store(facet, 1, newSVnv(THIS->stl.v_indices[i].vertex[1]));
-            av_store(facet, 2, newSVnv(THIS->stl.v_indices[i].vertex[2]));
+            av_store(facet, 0, newSVnv(THIS->its.indices[i][0]));
+            av_store(facet, 1, newSVnv(THIS->its.indices[i][1]));
+            av_store(facet, 2, newSVnv(THIS->its.indices[i][2]));
         }
         
         RETVAL = newRV_noinc((SV*)facets);