Do mesh booleans with cgal if possible.

src/libslic3r/CSGMesh/PerformCSGMeshBooleans.hpp

@@ -5,15 +5,58 @@
 
 #include "libslic3r/MeshBoolean.hpp"
 
-namespace Slic3r {
+namespace Slic3r { namespace csg {
+
+// This method can be overriden when a specific CSGPart type supports caching
+// of the voxel grid
+template<class CSGPartT>
+MeshBoolean::cgal::CGALMeshPtr get_cgalmesh(const CSGPartT &csgpart)
+{
+    const indexed_triangle_set *its = csg::get_mesh(csgpart);
+    MeshBoolean::cgal::CGALMeshPtr ret;
+
+    if (its) {
+        indexed_triangle_set m = *its;
+        its_transform(m, get_transform(csgpart));
+        ret = MeshBoolean::cgal::triangle_mesh_to_cgal(m);
+    }
+
+    return ret;
+}
 
 template<class It>
 void perform_csgmesh_booleans(MeshBoolean::cgal::CGALMesh &cgalm,
-                              const Range<It>             &csg)
+                              const Range<It>             &csgparts)
 {
-
+    for (auto &csgpart : csgparts) {
+        auto m = get_cgalmesh(csgpart);
+        if (m) {
+            switch (get_operation(csgpart)) {
+            case CSGType::Union:
+                MeshBoolean::cgal::plus(cgalm, *m);
+                break;
+            case CSGType::Difference:
+                MeshBoolean::cgal::minus(cgalm, *m);
+                break;
+            case CSGType::Intersection:
+                MeshBoolean::cgal::intersect(cgalm, *m);
+                break;
+            }
+        }
+    }
 }
 
+template<class It>
+MeshBoolean::cgal::CGALMeshPtr perform_csgmesh_booleans(const Range<It> &csgparts)
+{
+    auto ret = MeshBoolean::cgal::triangle_mesh_to_cgal(indexed_triangle_set{});
+    if (ret)
+        perform_csgmesh_booleans(*ret, csgparts);
+
+    return ret;
+}
+
+} // namespace csg
 } // namespace Slic3r
 
 #endif // PERFORMCSGMESHBOOLEANS_HPP

src/libslic3r/CSGMesh/SliceCSGMesh.hpp

@@ -52,6 +52,8 @@ std::vector<ExPolygons> slice_csgmesh_ex(
                 return p.area() < double(SCALED_EPSILON) * double(SCALED_EPSILON);
             });
 
+            // Hopefully, ExPolygons are moved, not copied to new positions
+            // and that is cheap for expolygons
             slice.erase(it, slice.end());
         }
     }

src/libslic3r/MeshBoolean.hpp

@@ -26,16 +26,17 @@ namespace cgal {
 
 struct CGALMesh;
 struct CGALMeshDeleter { void operator()(CGALMesh *ptr); };
+using CGALMeshPtr = std::unique_ptr<CGALMesh, CGALMeshDeleter>;
 
-std::unique_ptr<CGALMesh, CGALMeshDeleter>
-triangle_mesh_to_cgal(const std::vector<stl_vertex> &V,
-                      const std::vector<stl_triangle_vertex_indices> &F);
+CGALMeshPtr triangle_mesh_to_cgal(
+    const std::vector<stl_vertex> &V,
+    const std::vector<stl_triangle_vertex_indices> &F);
 
-inline std::unique_ptr<CGALMesh, CGALMeshDeleter> triangle_mesh_to_cgal(const indexed_triangle_set &M)
+inline CGALMeshPtr triangle_mesh_to_cgal(const indexed_triangle_set &M)
 {
     return triangle_mesh_to_cgal(M.vertices, M.indices);
 }
-inline std::unique_ptr<CGALMesh, CGALMeshDeleter> triangle_mesh_to_cgal(const TriangleMesh &M)
+inline CGALMeshPtr triangle_mesh_to_cgal(const TriangleMesh &M)
 {
     return triangle_mesh_to_cgal(M.its);
 }

src/libslic3r/SLAPrintSteps.cpp

@@ -18,11 +18,13 @@
 #include <libslic3r/SlicesToTriangleMesh.hpp>
 #include <libslic3r/CSGMesh/ModelToCSGMesh.hpp>
 #include <libslic3r/CSGMesh/SliceCSGMesh.hpp>
+#include <libslic3r/CSGMesh/VoxelizeCSGMesh.hpp>>
+#include <libslic3r/CSGMesh/PerformCSGMeshBooleans.hpp>
 #include <libslic3r/OpenVDBUtils.hpp>
 #include <libslic3r/QuadricEdgeCollapse.hpp>
 
 #include <libslic3r/ClipperUtils.hpp>
-#include <libslic3r/ShortEdgeCollapse.hpp>
+//#include <libslic3r/ShortEdgeCollapse.hpp>
 
 #include <boost/log/trivial.hpp>
 
@@ -128,48 +130,50 @@ void SLAPrint::Steps::apply_printer_corrections(SLAPrintObject &po, SliceOrigin
     }
 }
 
-
-void SLAPrint::Steps::generate_preview(SLAPrintObject &po, SLAPrintObjectStep step)
+indexed_triangle_set SLAPrint::Steps::generate_preview_vdb(
+    SLAPrintObject &po, SLAPrintObjectStep step)
 {
     Benchmark bench;
 
     bench.start();
+
     // update preview mesh
     double vscale = 1. / (2. * po.m_config.layer_height.getFloat());
     auto   voxparams = csg::VoxelizeParams{}
                          .voxel_scale(vscale)
                          .exterior_bandwidth(1.f)
                          .interior_bandwidth(1.f);
+
     auto grid = csg::voxelize_csgmesh(range(po.m_mesh_to_slice), voxparams);
 
     indexed_triangle_set m = grid_to_mesh(*grid);
 
-//    if (!m.empty()) {
-//        // simplify mesh lossless
+    bench.stop();
 
-//        std::cout << "simplify started" << std::endl;
-//        int expected_cnt = m.indices.size() * 0.8; //std::pow(po.m_transformed_rmesh.volume() / std::pow(1./vscale, 3), 2./3.);
-//        std::cout << "expected triangles " << expected_cnt << std::endl;
-//        float err = std::pow(vscale, 3);
-//        its_quadric_edge_collapse(m, 0U, &err);
-//        std::cout << "simplify ended " << m.indices.size() << " triangles" << std::endl;
+    std::cout << "Preview gen took: " << bench.getElapsedSec() << std::endl;
 
-//        std::cout << "cleanup started" << std::endl;
-//        its_compactify_vertices(m);
-//        its_merge_vertices(m);
-//        std::cout << "cleanup ended" << std::endl;
-//    }
+    return m;
+}
 
-    po.m_preview_meshes[step] = TriangleMesh{std::move(m)};
+
+void SLAPrint::Steps::generate_preview(SLAPrintObject &po, SLAPrintObjectStep step)
+{
+    MeshBoolean::cgal::CGALMeshPtr cgalptr;
+
+    try {
+        cgalptr = csg::perform_csgmesh_booleans(range(po.m_mesh_to_slice));
+    } catch(...) {}
+
+    if (cgalptr) {
+        po.m_preview_meshes[step] = MeshBoolean::cgal::cgal_to_triangle_mesh(*cgalptr);
+    } else
+        po.m_preview_meshes[step] = TriangleMesh{generate_preview_vdb(po, step)};
 
     for (size_t i = size_t(step) + 1; i < slaposCount; ++i)
     {
         po.m_preview_meshes[i] = {};
     }
 
-    bench.stop();
-
-    std::cout << "Preview gen took: " << bench.getElapsedSec() << std::endl;
     using namespace std::string_literals;
 
     report_status(-2, "Reload preview from step "s + std::to_string(int(step)), SlicingStatus::RELOAD_SLA_PREVIEW);

src/libslic3r/SLAPrintSteps.hpp

@@ -46,7 +46,8 @@ private:
     void apply_printer_corrections(SLAPrintObject &po, SliceOrigin o);
 
     void generate_preview(SLAPrintObject &po, SLAPrintObjectStep step);
-    
+    indexed_triangle_set generate_preview_vdb(SLAPrintObject &po, SLAPrintObjectStep step);
+
 public:
     explicit Steps(SLAPrint *print);