Fix thinwall-merge to keep a real loop

1 files changed, 52 insertions, 3 deletions

diff --git a/src/libslic3r/PerimeterGenerator.cpp b/src/libslic3r/PerimeterGenerator.cpp
index 8df16a5cd..4602e84ce 100644
--- a/src/libslic3r/PerimeterGenerator.cpp
+++ b/src/libslic3r/PerimeterGenerator.cpp
@@ -24,7 +24,18 @@
 #include <boost/log/trivial.hpp>
 
 namespace Slic3r {
-
+#if _DEBUG
+struct LoopAssertVisitor : public ExtrusionVisitorRecursiveConst {
+    virtual void default_use(const ExtrusionEntity& entity) override {};
+    virtual void use(const ExtrusionLoop& loop) override {
+        for (auto it = std::next(loop.paths.begin()); it != loop.paths.end(); ++it) {
+            assert(it->polyline.points.size() >= 2);
+            assert(std::prev(it)->polyline.last_point() == it->polyline.first_point());
+        }
+        assert(loop.paths.front().first_point() == loop.paths.back().last_point());
+    }
+};
+#endif
 PerimeterGeneratorLoops get_all_Childs(PerimeterGeneratorLoop loop) {
     PerimeterGeneratorLoops ret;
     for (PerimeterGeneratorLoop &child : loop.children) {
@@ -946,7 +957,7 @@ void PerimeterGenerator::process()
                                 contours.emplace_back();
                                 holes.emplace_back();
                             }
-                            //Add the new periemter
+                        //Add the new perimeter
                             contours[contours_size].emplace_back(contour_expolygon.front().contour, contours_size, true, has_steep_overhang, fuzzify_gapfill);
                             //create the new gapfills
                             ExPolygons gapfill_area = offset_ex(Polygons{ expoly.contour }, -(float)(perimeter_spacing));
@@ -1051,6 +1062,9 @@ void PerimeterGenerator::process()
                     peri_entities = this->_traverse_loops(contours.front(), thin_walls_thickpolys);
                 }
             }
+#if _DEBUG
+        peri_entities.visit(LoopAssertVisitor{});
+#endif
             //{
             //    static int aodfjiaqsdz = 0;
             //    std::stringstream stri;
@@ -1135,6 +1149,9 @@ void PerimeterGenerator::process()
                 this->loops->append(peri_entities);
             }
         } // for each loop of an island
+#if _DEBUG
+    this->loops->visit(LoopAssertVisitor{});
+#endif
 
         // fill gaps
         ExPolygons gaps_ex;
@@ -1783,7 +1800,27 @@ void PerimeterGenerator::_merge_thin_walls(ExtrusionEntityCollection &extrusions
     public:
         float percent_extrusion;
         std::vector<ExtrusionPath> paths;
+        Point* first_point = nullptr;
+        coordf_t resolution_sqr;
         virtual void use(ExtrusionPath &path) override {
+            //ensure the loop is continue.
+            if (first_point != nullptr) {
+                if (*first_point != path.first_point()) {
+                    if (first_point->distance_to_square(path.first_point()) < resolution_sqr) {
+                        path.polyline.points[0] = *first_point;
+                    } else {
+                        //add travel
+                        ExtrusionPath travel(path.role());
+                        travel.width = path.width;
+                        travel.height = path.height;
+                        travel.mm3_per_mm = 0;
+                        travel.polyline.points.push_back(*first_point);
+                        travel.polyline.points.push_back(path.first_point());
+                        paths.push_back(travel);
+                    }
+                }
+                first_point = nullptr;
+            }
             path.mm3_per_mm *= percent_extrusion;
             path.width *= percent_extrusion;
             paths.push_back(path);
@@ -1884,6 +1921,9 @@ void PerimeterGenerator::_merge_thin_walls(ExtrusionEntityCollection &extrusions
         //now insert thin wall if it has a point
         //it found a segment
         if (searcher.search_result.path != nullptr) {
+#if _DEBUG
+            searcher.search_result.loop->visit(LoopAssertVisitor{});
+#endif
             if (!searcher.search_result.from_start)
                 tw.reverse();
             //get the point
@@ -1904,20 +1944,25 @@ void PerimeterGenerator::_merge_thin_walls(ExtrusionEntityCollection &extrusions
             //create thin wall path exttrusion
             ExtrusionEntityCollection tws;
             tws.append(Geometry::thin_variable_width({ tw }, erThinWall, this->ext_perimeter_flow, std::max(ext_perimeter_flow.scaled_width() / 4, scale_t(this->print_config->resolution))));
+            assert(!tws.entities().empty());
             ChangeFlow change_flow;
             if (tws.entities().size() == 1 && tws.entities()[0]->is_loop()) {
                 //loop, just add it 
+                change_flow.first_point = &point;
                 change_flow.percent_extrusion = 1;
                 change_flow.use(tws);
                 //add move back
-
                 searcher.search_result.loop->paths.insert(searcher.search_result.loop->paths.begin() + 1 + searcher.search_result.idx_path,
                     change_flow.paths.begin(), change_flow.paths.end());
                 //add move to
 
+#if _DEBUG
+                searcher.search_result.loop->visit(LoopAssertVisitor{});
+#endif
             } else {
                 //first add the return path
                 //ExtrusionEntityCollection tws_second = tws; // this does a deep copy
+                change_flow.first_point = &point;
                 change_flow.percent_extrusion = 0.1f;
                 change_flow.use(tws); // tws_second); //does not need the deep copy if the change_flow copy the content instead of re-using it.
                 //force reverse
@@ -1928,11 +1973,15 @@ void PerimeterGenerator::_merge_thin_walls(ExtrusionEntityCollection &extrusions
                 searcher.search_result.loop->paths.insert(searcher.search_result.loop->paths.begin() + 1 + searcher.search_result.idx_path,
                     change_flow.paths.begin(), change_flow.paths.end());
                 //add the real extrusion path
+                change_flow.first_point = &point;
                 change_flow.percent_extrusion = 9.f; // 0.9 but as we modified it by 0.1 just before, has to multiply by 10
                 change_flow.paths = std::vector<ExtrusionPath>();
                 change_flow.use(tws);
                 searcher.search_result.loop->paths.insert(searcher.search_result.loop->paths.begin() + 1 + searcher.search_result.idx_path,
                     change_flow.paths.begin(), change_flow.paths.end());
+#if _DEBUG
+                searcher.search_result.loop->visit(LoopAssertVisitor{});
+#endif
             }
         } else {
             not_added.push_back(tw);