Fix for prusa3d/PrusaSlicer#11487 - Cut Connectors Broken when assigning part to other side

+ Added check objects after cut
+ CutUtils: Ensuring that volumes start with solid parts after solid parts merging for proper slicing

(cherry picked from commit prusa3d/PrusaSlicer@a9410edc2c)

src/libslic3r/CutUtils.cpp

@@ -395,6 +395,9 @@ static void distribute_modifiers_from_object(ModelObject* from_obj, const int in
 
     for (ModelVolume* vol : from_obj->volumes)
         if (!vol->is_model_part()) {
+            // Don't add modifiers which are processed connectors
+            if (vol->cut_info.is_connector && !vol->cut_info.is_processed)
+                continue;
             auto bb = vol->mesh().transformed_bounding_box(inst_matrix * vol->get_matrix());
             // Don't add modifiers which are not intersecting with solid parts
             if (obj1_bb.intersects(bb))
@@ -425,6 +428,8 @@ static void merge_solid_parts_inside_object(ModelObjectPtrs& objects)
                 if (mv->is_model_part() && !mv->is_cut_connector())
                     mo->delete_volume(i);
             }
+            // Ensuring that volumes start with solid parts for proper slicing
+            mo->sort_volumes(true);
         }
     }
 }

src/libslic3r/CutUtils.hpp

@@ -65,8 +65,6 @@ public:
 
 }; // namespace Cut
 
-
-
 } // namespace Slic3r
 
 #endif /* slic3r_CutUtils_hpp_ */

src/slic3r/GUI/Gizmos/GLGizmoCut.cpp

@@ -3290,6 +3290,32 @@ void update_object_cut_id(CutObjectBase& cut_id, ModelObjectCutAttributes attrib
     }
 }
 
+static void check_objects_after_cut(const ModelObjectPtrs& objects)
+{
+    std::vector<std::string> err_objects_names;
+    for (const ModelObject* object : objects) {
+        std::vector<std::string> connectors_names;
+        connectors_names.reserve(object->volumes.size());
+        for (const ModelVolume* vol : object->volumes)
+            if (vol->cut_info.is_connector)
+                connectors_names.push_back(vol->name);
+        const size_t connectors_count = connectors_names.size();
+        sort_remove_duplicates(connectors_names);
+        if (connectors_count != connectors_names.size())
+            err_objects_names.push_back(object->name);
+    }
+    if (err_objects_names.empty())
+        return;
+
+    wxString names = from_u8(err_objects_names[0]);
+    for (size_t i = 1; i < err_objects_names.size(); i++)
+        names += ", " + from_u8(err_objects_names[i]);
+    WarningDialog(wxGetApp().plater(), format_wxstr("Objects(%1%) have duplicated connectors. "
+                                "Some connectors may be missing in slicing result.\n"
+                                "Please report to PrusaSlicer team in which scenario this issue happened.\n"
+                                "Thank you.", names)).ShowModal();
+}
+
 void synchronize_model_after_cut(Model& model, const CutObjectBase& cut_id)
 {
     for (ModelObject* obj : model.objects)
@@ -3354,6 +3380,9 @@ void GLGizmoCut3D::perform_cut(const Selection& selection)
         const ModelObjectPtrs& new_objects = cut_by_contour    ? cut.perform_by_contour(m_part_selection.get_cut_parts(), dowels_count):
                                              cut_with_groove   ? cut.perform_with_groove(m_groove, m_rotation_m) :
                                                                  cut.perform_with_plane();
+
+        check_objects_after_cut(new_objects);
+
         // save cut_id to post update synchronization
         const CutObjectBase cut_id = cut_mo->cut_id;