Fix various issues with fuzzy skin (#6716)

* Fix issue that `fuzzy_skin_first_layer` not respected by classic wall generator

* Fix issue that Contour / Contour and hole mode not working properly (SoftFever/OrcaSlicer#6414)

* We have `is_contour`, so need for complicated hole detection

src/libslic3r/PerimeterGenerator.cpp

@@ -1835,7 +1835,8 @@ void PerimeterGenerator::process_classic()
                     break;
                 }
                 {
-                    const bool fuzzify_contours = this->config->fuzzy_skin != FuzzySkinType::None && ((i == 0 && this->layer_id > 0) || this->config->fuzzy_skin == FuzzySkinType::AllWalls);
+                    const bool fuzzify_layer = (this->config->fuzzy_skin_first_layer || this->layer_id>0) && this->config->fuzzy_skin != FuzzySkinType::None;
+                    const bool fuzzify_contours = fuzzify_layer && (i == 0 || this->config->fuzzy_skin == FuzzySkinType::AllWalls);
                     const bool fuzzify_holes = fuzzify_contours && (this->config->fuzzy_skin == FuzzySkinType::All || this->config->fuzzy_skin == FuzzySkinType::AllWalls);
                     for (const ExPolygon& expolygon : offsets) {
                         // Outer contour may overlap with an inner contour,
@@ -2846,44 +2847,19 @@ void PerimeterGenerator::process_arachne()
                     current_position = best_path->junctions.back().p; //Pick the other end from where we started.
             }
         }
-        if ((this->config->fuzzy_skin_first_layer || this->layer_id>0) && this->config->fuzzy_skin != FuzzySkinType::None) {
-            std::vector<PerimeterGeneratorArachneExtrusion*> closed_loop_extrusions;
-            for (PerimeterGeneratorArachneExtrusion& extrusion : ordered_extrusions)
-                if (extrusion.extrusion->inset_idx == 0) {
+        const bool fuzzify_layer = (this->config->fuzzy_skin_first_layer || this->layer_id>0) && this->config->fuzzy_skin != FuzzySkinType::None;
+        if (fuzzify_layer) {
+            for (PerimeterGeneratorArachneExtrusion& extrusion : ordered_extrusions) {
+                if (this->config->fuzzy_skin == FuzzySkinType::AllWalls) {
+                    extrusion.fuzzify = true;
+                } else if (extrusion.extrusion->inset_idx == 0) {
                     if (extrusion.extrusion->is_closed && this->config->fuzzy_skin == FuzzySkinType::External) {
-                        closed_loop_extrusions.emplace_back(&extrusion);
+                        extrusion.fuzzify = extrusion.is_contour;
                     }
                     else {
                         extrusion.fuzzify = true;
                     }
                 }
-
-            if (this->config->fuzzy_skin == FuzzySkinType::External) {
-                ClipperLib_Z::Paths loops_paths;
-                loops_paths.reserve(closed_loop_extrusions.size());
-                for (const auto& cl_extrusion : closed_loop_extrusions) {
-                    assert(cl_extrusion->extrusion->junctions.front() == cl_extrusion->extrusion->junctions.back());
-                    size_t             loop_idx = &cl_extrusion - &closed_loop_extrusions.front();
-                    ClipperLib_Z::Path loop_path;
-                    loop_path.reserve(cl_extrusion->extrusion->junctions.size() - 1);
-                    for (auto junction_it = cl_extrusion->extrusion->junctions.begin(); junction_it != std::prev(cl_extrusion->extrusion->junctions.end()); ++junction_it)
-                        loop_path.emplace_back(junction_it->p.x(), junction_it->p.y(), loop_idx);
-                    loops_paths.emplace_back(loop_path);
-                }
-
-                ClipperLib_Z::Clipper clipper;
-                clipper.AddPaths(loops_paths, ClipperLib_Z::ptSubject, true);
-                ClipperLib_Z::PolyTree loops_polytree;
-                clipper.Execute(ClipperLib_Z::ctUnion, loops_polytree, ClipperLib_Z::pftEvenOdd, ClipperLib_Z::pftEvenOdd);
-
-                for (const ClipperLib_Z::PolyNode* child_node : loops_polytree.Childs) {
-                    // The whole contour must have the same index.
-                    coord_t polygon_idx = child_node->Contour.front().z();
-                    bool    has_same_idx = std::all_of(child_node->Contour.begin(), child_node->Contour.end(),
-                        [&polygon_idx](const ClipperLib_Z::IntPoint& point) -> bool { return polygon_idx == point.z(); });
-                    if (has_same_idx)
-                        closed_loop_extrusions[polygon_idx]->fuzzify = true;
-                }
             }
         }