TriangleMeshSlicer is now initialized by const-pointer to the mesh, responsibility for calling require_shared_vertices is left to the caller

src/libslic3r/Model.cpp

@@ -1189,6 +1189,7 @@ ModelObjectPtrs ModelObject::cut(size_t instance, coordf_t z, bool keep_upper, b
             volume->mesh.transform(instance_matrix * volume_matrix, true);
 
             // Perform cut
+            volume->mesh.require_shared_vertices(); // TriangleMeshSlicer needs this
             TriangleMeshSlicer tms(&volume->mesh);
             tms.cut(float(z), &upper_mesh, &lower_mesh);
 

src/libslic3r/PrintObject.cpp

@@ -1813,6 +1813,7 @@ std::vector<ExPolygons> PrintObject::_slice_volumes(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
             mslicer.init(&mesh, callback);
 			mslicer.slice(z, float(m_config.slice_closing_radius.value), &layers, callback);
             m_print->throw_if_canceled();
@@ -1840,6 +1841,7 @@ 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
         mslicer.init(&mesh, callback);
         mslicer.slice(z, float(m_config.slice_closing_radius.value), &layers, callback);
         m_print->throw_if_canceled();

src/libslic3r/SLA/SLABasePool.cpp

@@ -552,6 +552,7 @@ void base_plate(const TriangleMesh &mesh, ExPolygons &output, float h,
                 float layerh, ThrowOnCancel thrfn)
 {
     TriangleMesh m = mesh;
+    m.require_shared_vertices(); // TriangleMeshSlicer needs this
     TriangleMeshSlicer slicer(&m);
 
     auto bb = mesh.bounding_box();

src/libslic3r/SLA/SLASupportTree.cpp

@@ -2231,6 +2231,7 @@ SlicedSupports SLASupportTree::slice(float layerh, float init_layerh) const
 
     TriangleMesh fullmesh = m_impl->merged_mesh();
     fullmesh.merge(get_pad());
+    fullmesh.require_shared_vertices(); // TriangleMeshSlicer needs this
     TriangleMeshSlicer slicer(&fullmesh);
     SlicedSupports ret;
     slicer.slice(heights, 0.f, &ret, get().ctl().cancelfn);
@@ -2243,6 +2244,7 @@ SlicedSupports SLASupportTree::slice(const std::vector<float> &heights,
 {
     TriangleMesh fullmesh = m_impl->merged_mesh();
     fullmesh.merge(get_pad());
+    fullmesh.require_shared_vertices(); // TriangleMeshSlicer needs this
     TriangleMeshSlicer slicer(&fullmesh);
     SlicedSupports ret;
     slicer.slice(heights, cr, &ret, get().ctl().cancelfn);

src/libslic3r/SLAPrint.cpp

@@ -706,6 +706,7 @@ void SLAPrint::process()
             po.m_model_height_levels.emplace_back(it->slice_level());
         }
 
+        mesh.require_shared_vertices(); // TriangleMeshSlicer needs this
         TriangleMeshSlicer slicer(&mesh);
 
         po.m_model_slices.clear();

src/libslic3r/TriangleMesh.cpp

@@ -607,10 +607,12 @@ void TriangleMesh::require_shared_vertices()
     BOOST_LOG_TRIVIAL(trace) << "TriangleMeshSlicer::require_shared_vertices - end";
 }
 
-void TriangleMeshSlicer::init(TriangleMesh *_mesh, throw_on_cancel_callback_type throw_on_cancel)
+void TriangleMeshSlicer::init(const TriangleMesh *_mesh, throw_on_cancel_callback_type throw_on_cancel)
 {
     mesh = _mesh;
-    _mesh->require_shared_vertices();
+    if (! mesh->has_shared_vertices())
+        throw std::invalid_argument("TriangleMeshSlicer was passed a mesh without shared vertices.");
+
     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);

src/libslic3r/TriangleMesh.hpp

@@ -67,18 +67,17 @@ public:
     TriangleMesh convex_hull_3d() const;
     void reset_repair_stats();
     bool needed_repair() const;
+    void require_shared_vertices();
+    bool   has_shared_vertices() const { return stl.v_shared != NULL; }
     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;
     bool repaired;
 
 private:
-    void require_shared_vertices();
     std::deque<uint32_t> find_unvisited_neighbors(std::vector<unsigned char> &facet_visited) const;
-    friend class TriangleMeshSlicer;
 };
 
 enum FacetEdgeType { 
@@ -159,9 +158,8 @@ class TriangleMeshSlicer
 public:
     typedef std::function<void()> throw_on_cancel_callback_type;
     TriangleMeshSlicer() : mesh(nullptr) {}
-    // Not quite nice, but the constructor and init() methods require non-const mesh pointer to be able to call mesh->require_shared_vertices()
+	TriangleMeshSlicer(const TriangleMesh* mesh) { this->init(mesh, [](){}); }
-	TriangleMeshSlicer(TriangleMesh* mesh) { this->init(mesh, [](){}); }
+    void init(const TriangleMesh *mesh, throw_on_cancel_callback_type throw_on_cancel);
-    void init(TriangleMesh *mesh, throw_on_cancel_callback_type throw_on_cancel);
     void slice(const std::vector<float> &z, std::vector<Polygons>* layers, throw_on_cancel_callback_type throw_on_cancel) const;
     void slice(const std::vector<float> &z, const float closing_radius, std::vector<ExPolygons>* layers, throw_on_cancel_callback_type throw_on_cancel) const;
     enum FacetSliceType {

src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.cpp

@@ -178,6 +178,7 @@ void GLGizmoSlaSupports::render_clipping_plane(const Selection& selection, const
                     // The timestamp has changed - stash the mesh and initialize the TMS.
                     m_supports_mesh = print_object->support_mesh();
                     m_supports_tms.reset(new TriangleMeshSlicer);
+                    m_supports_mesh.require_shared_vertices(); // TriangleMeshSlicer needs this
                     m_supports_tms->init(const_cast<TriangleMesh*>(&m_supports_mesh), [](){});
                     m_old_timestamp = timestamp;
                 }
@@ -411,6 +412,7 @@ void GLGizmoSlaSupports::update_mesh()
     Eigen::MatrixXi& F = m_F;
     // This mesh does not account for the possible Z up SLA offset.
     m_mesh = m_model_object->raw_mesh();
+    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);