Add support for csg operation stacking

src/libslic3r/CSGMesh/CSGMesh.hpp

@@ -18,6 +18,7 @@ namespace Slic3r { namespace csg {
 
 // Supported CSG operation types
 enum class CSGType { Union, Difference, Intersection };
+enum class CSGStackOp { Push, Continue, Pop };
 
 // Get the CSG operation of the part. Can be overriden for any type
 template<class CSGPartT> CSGType get_operation(const CSGPartT &part)
@@ -25,6 +26,11 @@ template<class CSGPartT> CSGType get_operation(const CSGPartT &part)
     return part.operation;
 }
 
+template<class CSGPartT> CSGStackOp get_stack_operation(const CSGPartT &part)
+{
+    return part.stack_operation;
+}
+
 // Get the mesh for the part. Can be overriden for any type
 template<class CSGPartT>
 const indexed_triangle_set *get_mesh(const CSGPartT &part)
@@ -48,6 +54,11 @@ inline CSGType get_operation(const indexed_triangle_set &part)
     return CSGType::Union;
 }
 
+inline CSGStackOp get_stack_operation(const indexed_triangle_set &part)
+{
+    return CSGStackOp::Continue;
+}
+
 inline const indexed_triangle_set * get_mesh(const indexed_triangle_set &part)
 {
     return &part;
@@ -63,6 +74,7 @@ struct CSGPart {
     AnyPtr<const indexed_triangle_set> its_ptr;
     Transform3f trafo;
     CSGType operation;
+    CSGStackOp stack_operation;
 
     CSGPart(AnyPtr<const indexed_triangle_set> ptr = {},
             CSGType                            op  = CSGType::Union,

src/libslic3r/CSGMesh/ModelToCSGMesh.hpp

@@ -5,13 +5,15 @@
 
 #include "libslic3r/Model.hpp"
 #include "libslic3r/SLA/Hollowing.hpp"
+#include "libslic3r/MeshSplitImpl.hpp"
 
 namespace Slic3r { namespace csg {
 
 enum ModelParts {
     mpartsPositive = 1,
     mpartsNegative = 2,
-    mpartsDrillHoles = 4
+    mpartsDrillHoles = 4,
+    mpartsDoSplits = 8
 };
 
 template<class OutIt>
@@ -22,20 +24,43 @@ void model_to_csgmesh(const ModelObject &mo,
                       int                parts_to_include = mpartsPositive
                       )
 {
-    bool do_positives = parts_to_include & mpartsPositive;
-    bool do_negatives = parts_to_include & mpartsNegative;
+    bool do_positives  = parts_to_include & mpartsPositive;
+    bool do_negatives  = parts_to_include & mpartsNegative;
     bool do_drillholes = parts_to_include & mpartsDrillHoles;
+    bool do_splits     = parts_to_include & mpartsDoSplits;
 
     for (const ModelVolume *vol : mo.volumes) {
         if (vol && vol->mesh_ptr() &&
             ((do_positives && vol->is_model_part()) ||
              (do_negatives && vol->is_negative_volume()))) {
-            CSGPart part{&(vol->mesh().its),
-                vol->is_model_part() ? CSGType::Union : CSGType::Difference,
-             (trafo * vol->get_matrix()).cast<float>()};
 
-            *out = std::move(part);
-            ++out;
+            if (do_splits && its_is_splittable(vol->mesh().its)) {
+                CSGPart part_begin{{}, vol->is_model_part() ? CSGType::Union : CSGType::Difference};
+                part_begin.stack_operation = CSGStackOp::Push;
+                *out = std::move(part_begin);
+                ++out;
+
+                its_split(vol->mesh().its, SplitOutputFn{[&out, &vol, &trafo](indexed_triangle_set &&its) {
+                              CSGPart part{std::make_unique<indexed_triangle_set>(std::move(its)),
+                                       CSGType::Union,
+                                       (trafo * vol->get_matrix()).cast<float>()};
+
+                              *out = std::move(part);
+                              ++out;
+                          }});
+
+                CSGPart part_end{{}};
+                part_end.stack_operation = CSGStackOp::Pop;
+                *out = std::move(part_end);
+                ++out;
+            } else {
+                CSGPart part{&(vol->mesh().its),
+                             vol->is_model_part() ? CSGType::Union : CSGType::Difference,
+                             (trafo * vol->get_matrix()).cast<float>()};
+
+                *out = std::move(part);
+                ++out;
+            }
         }
     }
 

src/libslic3r/CSGMesh/SliceCSGMesh.hpp

@@ -2,6 +2,9 @@
 #define SLICECSGMESH_HPP
 
 #include "CSGMesh.hpp"
+
+#include <stack>
+
 #include "libslic3r/TriangleMeshSlicer.hpp"
 #include "libslic3r/ClipperUtils.hpp"
 #include "libslic3r/Execution/ExecutionTBB.hpp"
@@ -10,57 +13,107 @@ namespace Slic3r { namespace csg {
 
 template<class ItCSG>
 std::vector<ExPolygons> slice_csgmesh_ex(
-    const Range<ItCSG>          &csg,
+    const Range<ItCSG>          &csgrange,
     const std::vector<float>    &slicegrid,
     const MeshSlicingParamsEx   &params,
     const std::function<void()> &throw_on_cancel = [] {})
 {
-    std::vector<ExPolygons> ret(slicegrid.size());
+    struct Frame { CSGType op; std::vector<ExPolygons> slices; };
+
+    std::stack opstack{std::vector<Frame>{}};
 
     MeshSlicingParamsEx params_cpy = params;
     auto trafo = params.trafo;
     auto nonempty_indices = reserve_vector<size_t>(slicegrid.size());
 
-    for (const auto &m : csg) {
-        const indexed_triangle_set *its = csg::get_mesh(m);
-        if (!its)
-            continue;
+    if (!csgrange.empty() && csg::get_stack_operation(*csgrange.begin()) != CSGStackOp::Push)
+        opstack.push({CSGType::Union, std::vector<ExPolygons>(slicegrid.size())});
 
-        params_cpy.trafo = trafo * csg::get_transform(m).template cast<double>();
-        std::vector<ExPolygons> slices = slice_mesh_ex(*its,
-                                                       slicegrid, params_cpy,
-                                                       throw_on_cancel);
+    for (const auto &csgpart : csgrange) {
+        const indexed_triangle_set *its = csg::get_mesh(csgpart);
 
-        assert(slices.size() == slicegrid.size());
+        auto op = get_operation(csgpart);
 
-        nonempty_indices.clear();
-        for (size_t i = 0; i < slicegrid.size(); ++i) {
-            if (get_operation(m) == CSGType::Intersection || !slices[i].empty())
-                nonempty_indices.emplace_back(i);
+        if (get_stack_operation(csgpart) == CSGStackOp::Push) {
+            opstack.push({op, std::vector<ExPolygons>(slicegrid.size())});
+            op = CSGType::Union;
         }
 
-        auto mergefn = [&m, &slices, &ret](size_t i){
-            switch(get_operation(m)) {
-            case CSGType::Union:
-                for (ExPolygon &expoly : slices[i])
-                    ret[i].emplace_back(std::move(expoly));
+        Frame *top = &opstack.top();
 
-                break;
-            case CSGType::Difference:
-                ret[i] = diff_ex(ret[i], slices[i]);
-                break;
-            case CSGType::Intersection:
-                ret[i] = intersection_ex(ret[i], slices[i]);
-                break;
+        if (its) {
+            params_cpy.trafo = trafo * csg::get_transform(csgpart).template cast<double>();
+            std::vector<ExPolygons> slices = slice_mesh_ex(*its,
+                                                           slicegrid, params_cpy,
+                                                           throw_on_cancel);
+
+            assert(slices.size() == slicegrid.size());
+
+            nonempty_indices.clear();
+            for (size_t i = 0; i < slicegrid.size(); ++i) {
+                if (op == CSGType::Intersection || !slices[i].empty())
+                    nonempty_indices.emplace_back(i);
             }
-        };
 
-        execution::for_each(ex_tbb,
-                            nonempty_indices.begin(), nonempty_indices.end(),
-                            mergefn,
-                            execution::max_concurrency(ex_tbb));
+            auto mergefn = [&csgpart, &slices, &top](size_t i){
+                switch(get_operation(csgpart)) {
+                case CSGType::Union:
+                    for (ExPolygon &expoly : slices[i])
+                        top->slices[i].emplace_back(std::move(expoly));
+
+                    break;
+                case CSGType::Difference:
+                    top->slices[i] = diff_ex(top->slices[i], slices[i]);
+                    break;
+                case CSGType::Intersection:
+                    top->slices[i] = intersection_ex(top->slices[i], slices[i]);
+                    break;
+                }
+            };
+
+            execution::for_each(ex_tbb,
+                                nonempty_indices.begin(), nonempty_indices.end(),
+                                mergefn,
+                                execution::max_concurrency(ex_tbb));
+        }
+
+        if (get_stack_operation(csgpart) == CSGStackOp::Pop) {
+            std::vector<ExPolygons> popslices = std::move(top->slices);
+            auto popop = opstack.top().op;
+            opstack.pop();
+            std::vector<ExPolygons> &prev_slices = opstack.top().slices;
+
+            nonempty_indices.clear();
+            for (size_t i = 0; i < slicegrid.size(); ++i) {
+                if (popop == CSGType::Intersection || !popslices[i].empty())
+                    nonempty_indices.emplace_back(i);
+            }
+
+            auto mergefn2 = [&popslices, &prev_slices, popop](size_t i){
+                switch(popop) {
+                case CSGType::Union:
+                    for (ExPolygon &expoly : popslices[i])
+                        prev_slices[i].emplace_back(std::move(expoly));
+
+                    break;
+                case CSGType::Difference:
+                    prev_slices[i] = diff_ex(prev_slices[i], popslices[i]);
+                    break;
+                case CSGType::Intersection:
+                    prev_slices[i] = intersection_ex(prev_slices[i], popslices[i]);
+                    break;
+                }
+            };
+
+            execution::for_each(ex_tbb,
+                                nonempty_indices.begin(), nonempty_indices.end(),
+                                mergefn2,
+                                execution::max_concurrency(ex_tbb));
+        }
     }
 
+    std::vector<ExPolygons> ret = std::move(opstack.top().slices);
+
     execution::for_each(ex_tbb, ret.begin(), ret.end(), [](ExPolygons &slice) {
         auto it = std::remove_if(slice.begin(), slice.end(), [](const ExPolygon &p){
             return p.area() < double(SCALED_EPSILON) * double(SCALED_EPSILON);

src/libslic3r/CSGMesh/VoxelizeCSGMesh.hpp

@@ -2,6 +2,7 @@
 #define VOXELIZECSGMESH_HPP
 
 #include <functional>
+#include <stack>
 
 #include "CSGMesh.hpp"
 #include "libslic3r/OpenVDBUtils.hpp"
@@ -46,29 +47,65 @@ VoxelGridPtr voxelize_csgmesh(const Range<It>      &csgrange,
     }, execution::max_concurrency(ex_tbb));
 
     size_t csgidx = 0;
+    struct Frame { CSGType op = CSGType::Union; VoxelGridPtr grid; };
+    std::stack opstack{std::vector<Frame>{}};
+
+    if (!csgrange.empty() && csg::get_stack_operation(*csgrange.begin()) != CSGStackOp::Push)
+        opstack.push({});
+
     for (auto &csgpart : csgrange) {
         if (params.statusfn() && params.statusfn()(-1))
             break;
 
         auto &partgrid = grids[csgidx++];
 
-        if (!ret && get_operation(csgpart) == CSGType::Union) {
-            ret = std::move(partgrid);
-        } else if (ret) {
+        auto op = get_operation(csgpart);
+
+        if (get_stack_operation(csgpart) == CSGStackOp::Push) {
+            opstack.push({op, nullptr});
+            op = CSGType::Union;
+        }
+
+        Frame *top = &opstack.top();
+
+        if (!top->grid && op == CSGType::Union) {
+            top->grid = std::move(partgrid);
+        } else if (top->grid && partgrid) {
             switch (get_operation(csgpart)) {
             case CSGType::Union:
-                grid_union(*ret, *partgrid);
+                grid_union(*(top->grid), *partgrid);
                 break;
             case CSGType::Difference:
-                grid_difference(*ret, *partgrid);
+                grid_difference(*(top->grid), *partgrid);
                 break;
             case CSGType::Intersection:
-                grid_intersection(*ret, *partgrid);
+                grid_intersection(*(top->grid), *partgrid);
+                break;
+            }
+        }
+
+        if (get_stack_operation(csgpart) == CSGStackOp::Pop) {
+            VoxelGridPtr popgrid = std::move(top->grid);
+            auto popop = opstack.top().op;
+            opstack.pop();
+            VoxelGridPtr &grid = opstack.top().grid;
+
+            switch (popop) {
+            case CSGType::Union:
+                grid_union(*grid, *popgrid);
+                break;
+            case CSGType::Difference:
+                grid_difference(*grid, *popgrid);
+                break;
+            case CSGType::Intersection:
+                grid_intersection(*grid, *popgrid);
                 break;
             }
         }
     }
 
+    ret = std::move(opstack.top().grid);
+
     return ret;
 }
 

src/libslic3r/SLAPrint.cpp

@@ -1114,7 +1114,7 @@ VoxelGridPtr get_voxelgrid(const CSGPartForStep &part, VoxelizeParams p)
 {
     VoxelGridPtr &ret = part.gridcache[p];
 
-    if (!ret) {
+    if (!ret && csg::get_mesh(part)) {
         p.trafo(csg::get_transform(part));
         ret = mesh_to_grid(*csg::get_mesh(part), p);
     }

src/libslic3r/SLAPrintSteps.cpp

@@ -242,7 +242,7 @@ void SLAPrint::Steps::mesh_assembly(SLAPrintObject &po)
 
     csg::model_to_csgmesh(*po.model_object(), po.trafo(),
                           csg_inserter{po.m_mesh_to_slice, slaposAssembly},
-                          csg::mpartsPositive | csg::mpartsNegative);
+                          csg::mpartsPositive | csg::mpartsNegative | csg::mpartsDoSplits);
 
     generate_preview(po, slaposAssembly);
 }
@@ -352,9 +352,18 @@ template<class Cont> BoundingBoxf3 csgmesh_positive_bb(const Cont &csg)
                               bounding_box(*csg::get_mesh(*csg.begin()),
                                            csg::get_transform(*csg.begin()));
 
+    bool skip = false;
     for (const auto &m : csg) {
-        if (m.operation == csg::CSGType::Union)
+        auto op = csg::get_operation(m);
+        auto stackop = csg::get_stack_operation(m);
+        if (stackop == csg::CSGStackOp::Push && op != csg::CSGType::Union)
+            skip = true;
+
+        if (!skip && csg::get_mesh(m) && op == csg::CSGType::Union)
             bb3d.merge(bounding_box(*csg::get_mesh(m), csg::get_transform(m)));
+
+        if (stackop == csg::CSGStackOp::Pop)
+            skip = false;
     }
 
     return bb3d;