fix gapfill:

* fix gapfill after external perimeter: Happens if external perimeter has a different width than internal.
supermerill/SuperSlicer#1640
* revert 3b0c006 : not needed anymore. if ever needed again, I added a [size > 1] to fix the problem
supermerill/SuperSlicer#1758

src/libslic3r/MedialAxis.cpp

@@ -1727,12 +1727,13 @@ MedialAxis::build(ThickPolylines &polylines_out)
                 tp.width[i] = this->max_width;
             }
         }
-        // voronoi bugfix: when we have a wheel, it creates a polyline at the center, completly out of the polygon.
+        // voronoi bugfix: when we have a wheel, it creates a polyline at the center, completly out of the polygon. #651
-        if (tp.endpoints.first && tp.endpoints.second && !this->expolygon.contains(tp.first_point()) && !this->expolygon.contains(tp.last_point())) {
+        // note: can't reproduce in the new verison. This may have been fixed by another way.
-            //delete this out-of-bounds polyline
+        //if (tp.endpoints.first && tp.endpoints.second && !this->expolygon.contains(tp.first_point()) && !this->expolygon.contains(tp.last_point()) && pp.size() > 1) {
-            pp.erase(pp.begin() + tp_idx);
+        //    //delete this out-of-bounds polyline
-            --tp_idx;
+        //    pp.erase(pp.begin() + tp_idx);
-        }
+        //    --tp_idx;
+        //}
     }
     //std::cout << "polyline_from_voronoi\n";
     //{

src/libslic3r/PerimeterGenerator.cpp

@@ -43,15 +43,15 @@ void PerimeterGenerator::process()
 
     // other perimeters
     this->_mm3_per_mm               = this->perimeter_flow.mm3_per_mm();
-    coord_t perimeter_width         = this->perimeter_flow.scaled_width();
+    const coord_t perimeter_width         = this->perimeter_flow.scaled_width();
     //spacing between internal perimeters
-    coord_t perimeter_spacing       = this->perimeter_flow.scaled_spacing();
+    const coord_t perimeter_spacing       = this->perimeter_flow.scaled_spacing();
     
     // external perimeters
     this->_ext_mm3_per_mm           = this->ext_perimeter_flow.mm3_per_mm();
-    coord_t ext_perimeter_width     = this->ext_perimeter_flow.scaled_width();
+    const coord_t ext_perimeter_width     = this->ext_perimeter_flow.scaled_width();
     //spacing between two external perimeter (where you don't have the space to add other loops)
-    coord_t ext_perimeter_spacing   = this->ext_perimeter_flow.scaled_spacing();
+    const coord_t ext_perimeter_spacing   = this->ext_perimeter_flow.scaled_spacing();
     //spacing between external perimeter and the second
     coord_t ext_perimeter_spacing2  = this->ext_perimeter_flow.scaled_spacing(this->perimeter_flow);
 
@@ -59,19 +59,21 @@ void PerimeterGenerator::process()
     this->_mm3_per_mm_overhang = this->overhang_flow.mm3_per_mm();
 
     //gap fill
-    coord_t gap_fill_spacing = this->config->gap_fill_overlap.get_abs_value(this->perimeter_flow.scaled_spacing())  
+    const coord_t gap_fill_spacing_external = this->config->gap_fill_overlap.get_abs_value(this->ext_perimeter_flow.scaled_spacing())
-        + this->perimeter_flow.scaled_width() * (100 - this->config->gap_fill_overlap.value) / 100.;
+        + this->ext_perimeter_flow.scaled_width() * (1 - this->config->gap_fill_overlap.get_abs_value(1.));
+    const coord_t gap_fill_spacing = this->config->gap_fill_overlap.get_abs_value(this->perimeter_flow.scaled_spacing())
+        + this->perimeter_flow.scaled_width() * (1 - this->config->gap_fill_overlap.get_abs_value(1.));
 
     // solid infill
-    coord_t solid_infill_spacing = this->solid_infill_flow.scaled_spacing();
+    const coord_t solid_infill_spacing = this->solid_infill_flow.scaled_spacing();
 
     //infill / perimeter
     coord_t infill_peri_overlap = (coord_t)scale_(this->config->get_abs_value("infill_overlap", unscale<coordf_t>(perimeter_spacing + solid_infill_spacing) / 2));
     // infill gap to add vs perimeter (useful if using perimeter bonding)
     coord_t infill_gap = 0;
 
-    bool round_peri = this->config->perimeter_round_corners.value;
+    const bool round_peri = this->config->perimeter_round_corners.value;
-    coord_t min_round_spacing = perimeter_width / 10;
+    const coord_t min_round_spacing = perimeter_width / 10;
 
     // nozzle diameter
     const double nozzle_diameter = this->print_config->nozzle_diameter.get_at(this->config->perimeter_extruder - 1);
@@ -95,8 +97,8 @@ void PerimeterGenerator::process()
     // which is the spacing between external and internal, which is not correct
     // and would make the collapsing (thus the details resolution) dependent on 
     // internal flow which is unrelated. <- i don't undertand, so revert to ext_perimeter_spacing2
-    coord_t min_spacing     = (coord_t)( perimeter_spacing      * (1 - 0.05/*INSET_OVERLAP_TOLERANCE*/) );
+    const coord_t min_spacing     = (coord_t)( perimeter_spacing      * (1 - 0.05/*INSET_OVERLAP_TOLERANCE*/) );
-    coord_t ext_min_spacing = (coord_t)( ext_perimeter_spacing2  * (1 - 0.05/*INSET_OVERLAP_TOLERANCE*/) );
+    const coord_t ext_min_spacing = (coord_t)( ext_perimeter_spacing2  * (1 - 0.05/*INSET_OVERLAP_TOLERANCE*/) );
     
     // prepare grown lower layer slices for overhang detection
     if (this->lower_slices != NULL && (this->config->overhangs_width.value > 0 || this->config->overhangs_width_speed.value > 0)) {
@@ -651,11 +653,17 @@ void PerimeterGenerator::process()
                         no_last_gapfill = offset_ex(next_onion, 0.5f * good_spacing + 10,
                             (round_peri ? ClipperLib::JoinType::jtRound : ClipperLib::JoinType::jtMiter),
                             (round_peri ? min_round_spacing : 3));
+                        if (i == 1) {
+                            append(gaps, diff_ex(
+                                offset_ex(last, -0.5f * gap_fill_spacing_external),
+                                no_last_gapfill));  // safety offset
+                        } else {
                             append(gaps, diff_ex(
                                 offset_ex(last, -0.5f * gap_fill_spacing),
                                 no_last_gapfill));  // safety offset
                         }
                     }
+                }
 
                 if (next_onion.empty()) {
                     // Store the number of loops actually generated.