fix (snug) support too narrow

Also allow the periemter around support to overlap itself like with prusaslicer (unless there is a 0 support xy distance).
#4333

src/libslic3r/Fill/FillBase.cpp

@@ -3653,9 +3653,11 @@ FillWithPerimeter::fill_surface_extrusion(const Surface* surface, const FillPara
 
     // === extrude perimeter & associated surface at the same time, in the right order ===
     //generate perimeter:
-    ExPolygons path_perimeter = offset2_ex(ExPolygons{ surface->expolygon },
-        scale_d(-this->get_spacing()), scale_d(this->get_spacing() / 2),
-        ClipperLib::jtMiter, scale_d(this->get_spacing()) * 10);
+    coord_t offset_for_overlap = scale_d(this->get_spacing() / 2) * ((1 - overlap_ratio) / 2);
+    ExPolygons path_perimeter  = offset2_ex(ExPolygons{surface->expolygon},
+                                            scale_d(-this->get_spacing()) / 2 - offset_for_overlap,
+                                            offset_for_overlap,
+                                            ClipperLib::jtMiter, scale_d(this->get_spacing()) * 10);
     //fix a bug that can happens when (positive) offsetting with a big miter limit and two island merge. See https://github.com/supermerill/SuperSlicer/issues/609
     path_perimeter = intersection_ex(path_perimeter, offset_ex(surface->expolygon, scale_d(-this->get_spacing() / 2)));
     for (ExPolygon& expolygon : path_perimeter) {

src/libslic3r/Fill/FillBase.hpp

@@ -241,6 +241,8 @@ namespace NaiveConnect {
 class FillWithPerimeter : public Fill
 {
 public:
+    // bewteen 0 (0%) and 1 (100%) overlap
+    float overlap_ratio = 0;
     std::unique_ptr<Fill> infill{ nullptr };
     float ratio_fill_inside = 0.f;
     FillWithPerimeter() : Fill() {}

src/libslic3r/SupportMaterial.cpp

@@ -19,7 +19,7 @@
 #include <tbb/parallel_for.h>
 #include <tbb/spin_mutex.h>
 #include <tbb/task_group.h>
-
+#pragma optimize("", off)
 #define SUPPORT_USE_AGG_RASTERIZER
 
 #ifdef SUPPORT_USE_AGG_RASTERIZER
@@ -3912,10 +3912,10 @@ void modulate_extrusion_by_overlapping_layers(
         const PrintObjectSupportMaterial::MyLayer &overlapping_layer = *overlapping_layers[i_overlapping_layer];
         bbox.merge(get_extents(overlapping_layer.polygons));
     }
-    for (ExtrusionEntitiesPtr::const_iterator it = extrusions_in_out.begin(); it != extrusions_in_out.end(); ++ it) {
+    for (ExtrusionEntitiesPtr::const_iterator it = extrusions_in_out.set_entities().begin(); it != extrusions_in_out.set_entities().end(); ++ it) {
         ExtrusionPath *path = dynamic_cast<ExtrusionPath*>(*it);
         assert(path != nullptr);
-        bbox.merge(get_extents(path->polyline));
+        bbox.merge(get_extents(path->polyline.as_polyline()));
     }
     SVG svg(debug_out_path("support-fragments-%d-%lf.svg", iRun, this_layer.print_z).c_str(), bbox);
     const float transparency = 0.5f;
@@ -3932,10 +3932,10 @@ void modulate_extrusion_by_overlapping_layers(
         svg.draw(to_polylines(overlapping_layer.polygons), dbg_index_to_color(int(i_overlapping_layer)), scale_(0.1));
     }
     // Fill extrusion, the source.
-    for (ExtrusionEntitiesPtr::const_iterator it = extrusions_in_out.begin(); it != extrusions_in_out.end(); ++ it) {
+    for (ExtrusionEntitiesPtr::const_iterator it = extrusions_in_out.set_entities().begin(); it != extrusions_in_out.set_entities().end(); ++ it) {
         ExtrusionPath *path = dynamic_cast<ExtrusionPath*>(*it);
         std::string color_name;
-        switch ((it - extrusions_in_out.begin()) % 9) {
+        switch ((it - extrusions_in_out.set_entities().begin()) % 9) {
             case 0: color_name = "magenta"; break;
             case 1: color_name = "deepskyblue"; break;
             case 2: color_name = "coral"; break;
@@ -3946,7 +3946,7 @@ void modulate_extrusion_by_overlapping_layers(
             case 7: color_name = "brown"; break;
             default: color_name = "orchid"; break;
         }
-        svg.draw(path->polyline, color_name, scale_(0.2));
+        svg.draw(path->polyline.as_polyline(), color_name, scale_(0.2));
     }
 #endif /* SLIC3R_DEBUG */
 
@@ -4171,8 +4171,10 @@ void PrintObjectSupportMaterial::generate_toolpaths(
             std::unique_ptr<Fill> filler_interface = std::unique_ptr<Fill>(Fill::new_from_type(m_support_params.contact_fill_pattern)); //m_support_params.interface_fill_pattern)); FIXME choose
             std::unique_ptr<Fill> filler_support   = std::unique_ptr<Fill>(Fill::new_from_type(m_support_params.base_fill_pattern));
             std::unique_ptr<FillWithPerimeter> filler_support_with_sheath = std::make_unique<FillWithPerimeter>((Fill::new_from_type(m_support_params.base_fill_pattern)));
+            filler_support_with_sheath->overlap = m_support_params.gap_xy == 0 ? 0 : 1; // allow periemter overlap is not touching perimeters
             filler_support_with_sheath->ratio_fill_inside = 0.2f;
             std::unique_ptr<FillWithPerimeter> filler_dense = std::make_unique<FillWithPerimeter>((Fill::new_from_type(ipRectilinear)));
+            filler_dense->overlap = m_support_params.gap_xy == 0 ? 0 : 1;
             filler_dense->ratio_fill_inside = 0.2f;
             filler_interface->set_bounding_box(bbox_object);
             filler_support->set_bounding_box(bbox_object);
@@ -4489,7 +4491,7 @@ void PrintObjectSupportMaterial::generate_toolpaths(
                     // Destination
                     base_layer.extrusions.set_entities(),
                     // Regions to fill
-                    closing_ex(base_layer.polygons_to_extrude(), float(SCALED_EPSILON), float(SCALED_EPSILON + 0.5 * flow.scaled_width())),
+                    closing_ex(base_layer.polygons_to_extrude(), float(SCALED_EPSILON), float(SCALED_EPSILON)),
                     // Filler and its parameters
                     filler, density,
                     // Extrusion parameters