Fix medial axis creating points on top of each other.

supermerill/SuperSlicer#2099
supermerill/SuperSlicer#2102

src/libslic3r/MedialAxis.cpp

@@ -1330,8 +1330,12 @@ MedialAxis::concatenate_polylines_with_crossing(ThickPolylines& pp)
                     && polyline.width.back() > best_candidate->width[1]) {
                 polyline.width.back() = std::min(polyline.width[polyline.width.size() - 2], best_candidate->width[1]);
             }
-            polyline.points.insert(polyline.points.end(), best_candidate->points.begin() + 1, best_candidate->points.end());
+            //be far enough
-            polyline.width.insert(polyline.width.end(), best_candidate->width.begin() + 1, best_candidate->width.end());
+            int far_idx = 1;
+            while (far_idx < best_candidate->points.size() && polyline.last_point().coincides_with_epsilon(best_candidate->points[far_idx]))
+                far_idx++;
+            polyline.points.insert(polyline.points.end(), best_candidate->points.begin() + far_idx, best_candidate->points.end());
+            polyline.width.insert(polyline.width.end(), best_candidate->width.begin() + far_idx, best_candidate->width.end());
             polyline.endpoints.second = best_candidate->endpoints.second;
             assert(polyline.width.size() == polyline.points.size());
             if (best_idx < i) i--;
@@ -1799,6 +1803,24 @@ MedialAxis::build(ThickPolylines &polylines_out)
         //    pp.erase(pp.begin() + tp_idx);
         //    --tp_idx;
         //}
+        //voronoi problem: can put two consecutive points at the same position. Delete one.
+        for (size_t i = 1; i < tp.points.size()-1; i++) {
+            if (tp.points[i-1].distance_to_square(tp.points[i]) < SCALED_EPSILON) {
+                tp.points.erase(tp.points.begin() + i);
+                tp.width.erase(tp.width.begin() + i);
+                i--;
+            }
+        }
+        //delete the inner one
+        if (tp.points.size()>2 && tp.points[tp.points.size() - 2].distance_to_square(tp.points.back()) < SCALED_EPSILON) {
+            tp.points.erase(tp.points.end() - 2);
+            tp.width.erase(tp.width.end() - 2);
+        }
+        //delete null-length polylines
+        if (tp.length() < SCALED_EPSILON && tp.first_point().coincides_with_epsilon(tp.last_point())) {
+            pp.erase(pp.begin() + tp_idx);
+            --tp_idx;
+        }
     }
     //std::cout << "polyline_from_voronoi\n";
     //{
@@ -2078,8 +2100,11 @@ thin_variable_width(const ThickPolylines &polylines, ExtrusionRole role, Flow fl
                     continue;
                 }
             } else if (i > 0 && resolution_internal > line_len + prev_line_len) {
-                ThickLine& prev_line = lines[i - 1];
                 //merge lines?
+                //if it's a loop, merge only if the distance is high enough
+                if (p.first_point() == p.last_point() && p.length() < (line_len + prev_line_len) * 6)
+                    continue;
+                ThickLine& prev_line = lines[i - 1];
                 coordf_t width = prev_line_len * (prev_line.a_width + prev_line.b_width) / 2;
                 width += line_len * (line.a_width + line.b_width) / 2;
                 prev_line.b = line.b;
@@ -2149,6 +2174,7 @@ thin_variable_width(const ThickPolylines &polylines, ExtrusionRole role, Flow fl
                     path.height = flow.height;
                 }
             }
+            assert(path.polyline.points.size() > 2 || path.first_point() != path.last_point());
         }
         if (path.polyline.is_valid())
             paths.emplace_back(std::move(path));

src/libslic3r/libslic3r.h

@@ -34,32 +34,27 @@ using coord_t = int64_t;
 
 using coordf_t = double;
 
-//FIXME This epsilon value is used for many non-related purposes:
-// For a threshold of a squared Euclidean distance,
-// for a trheshold in a difference of radians,
-// for a threshold of a cross product of two non-normalized vectors etc.
-static constexpr double EPSILON = 1e-4;
 // Scaling factor for a conversion from coord_t to coordf_t: 10e-6
 // This scaling generates a following fixed point representation with for a 32bit integer:
 // 0..4294mm with 1nm resolution
 // int32_t fits an interval of (-2147.48mm, +2147.48mm)
 // with int64_t we don't have to worry anymore about the size of the int.
 static constexpr double SCALING_FACTOR = 0.000001;
-#ifdef __linux__
+static constexpr double UNSCALING_FACTOR = 1000000; // 1 / SCALING_FACTOR;
-static constexpr double UNSCALING_FACTOR = 1000000;
+
-#else
+//FIXME This epsilon value is used for many non-related purposes:
-static constexpr double UNSCALING_FACTOR = 1 / SCALING_FACTOR;
+// For a threshold of a squared Euclidean distance,
-#endif
+// for a trheshold in a difference of radians,
+// for a threshold of a cross product of two non-normalized vectors etc.
+static constexpr double EPSILON = 1e-4;
+static constexpr coord_t SCALED_EPSILON = 100; // coord_t(EPSILON/ SCALING_FACTOR);
 // RESOLUTION, SCALED_RESOLUTION: Used as an error threshold for a Douglas-Peucker polyline simplification algorithm.
 //#define RESOLUTION 0.0125
 //#define SCALED_RESOLUTION 12500
 //#define SCALED_RESOLUTION (RESOLUTION / SCALING_FACTOR)
 static constexpr coordf_t RESOLUTION = 0.0125;
-#ifdef __linux__
+static constexpr coord_t SCALED_RESOLUTION = 12500; // coord_t(0.0125 * UNSCALING_FACTOR);
-static constexpr coord_t SCALED_RESOLUTION = 12500;
+
-#else
-static constexpr coord_t SCALED_RESOLUTION = coord_t(0.0125 * UNSCALING_FACTOR);
-#endif
 //for creating circles (for brim_ear)
 #define POLY_SIDES 24
 #define PI 3.141592653589793238
@@ -72,7 +67,6 @@ static constexpr double INSET_OVERLAP_TOLERANCE = 0.4;
 //inline coord_t scale_(coordf_t v) { return coord_t(floor(v / SCALING_FACTOR + 0.5f)); }
 #define scale_(val) (coord_t)((val) / SCALING_FACTOR)
 
-#define SCALED_EPSILON scale_(EPSILON)
 
 #define SLIC3R_DEBUG_OUT_PATH_PREFIX "out/"