Only apply perimeter/infill overlap to the endpoints of rectilinear infill (and do that in a more proper way)

lib/Slic3r/Fill.pm

@@ -142,7 +142,7 @@ sub make_fill {
     # we are going to grow such regions by overlapping them with the void (if any)
     # TODO: detect and investigate whether there could be narrow regions without
     # any void neighbors
-    my $distance_between_surfaces = $infill_flow->scaled_spacing * &Slic3r::INFILL_OVERLAP_OVER_SPACING;
+    my $distance_between_surfaces = $infill_flow->scaled_spacing;
     {
         my $collapsed = diff(
             [ map @{$_->expolygon}, @surfaces ],

lib/Slic3r/Fill/Concentric.pm

@@ -26,9 +26,7 @@ sub fill_surface {
         $self->spacing(unscale $distance);
     }
     
-    # compensate the overlap which is good for rectilinear but harmful for concentric
+    my @loops = my @last = map $_->clone, @$expolygon;
-    # where the perimeter/infill spacing should be equal to any other loop spacing
-    my @loops = my @last = @{offset(\@$expolygon, -&Slic3r::INFILL_OVERLAP_OVER_SPACING * $min_spacing / 2)};
     while (@last) {
         push @loops, @last = @{offset2(\@last, -($distance + 0.5*$min_spacing), +0.5*$min_spacing)};
     }

lib/Slic3r/Fill/Rectilinear.pm

@@ -54,10 +54,21 @@ sub fill_surface {
     # the minimum offset for preventing edge lines from being clipped is scaled_epsilon;
     # however we use a larger offset to support expolygons with slightly skewed sides and 
     # not perfectly straight
-    my @polylines = @{intersection_pl(\@vertical_lines, $expolygon->offset(scale 0.02))};
+    my @polylines = @{intersection_pl(\@vertical_lines, $expolygon->offset(+scale 0.02))};
+    
+    my $extra = $self->_min_spacing * &Slic3r::INFILL_OVERLAP_OVER_SPACING;
+    foreach my $polyline (@polylines) {
+        my ($first_point, $last_point) = @$polyline[0,-1];
+        if ($first_point->y > $last_point->y) { #>
+            ($first_point, $last_point) = ($last_point, $first_point);
+        }
+        $first_point->set_y($first_point->y - $extra);  #--
+        $last_point->set_y($last_point->y + $extra);    #++
+    }
     
     # connect lines
     unless ($params{dont_connect} || !@polylines) {  # prevent calling leftmost_point() on empty collections
+        # offset the expolygon by max(min_spacing/2, extra)
         my ($expolygon_off) = @{$expolygon->offset_ex($self->_min_spacing/2)};
         my $collection = Slic3r::Polyline::Collection->new(@polylines);
         @polylines = ();

lib/Slic3r/Print/Object.pm

@@ -1009,7 +1009,7 @@ sub combine_infill {
                      # Because fill areas for rectilinear and honeycomb are grown 
                      # later to overlap perimeters, we need to counteract that too.
                      + (($type == S_TYPE_INTERNALSOLID || $region->config->fill_pattern =~ /(rectilinear|honeycomb)/)
-                       ? $layerms[-1]->flow(FLOW_ROLE_SOLID_INFILL)->scaled_width * &Slic3r::INFILL_OVERLAP_OVER_SPACING
+                       ? $layerms[-1]->flow(FLOW_ROLE_SOLID_INFILL)->scaled_width
                        : 0)
                      )}, @$intersection;
 

xs/xsp/Point.xsp

@@ -22,6 +22,10 @@
         %code{% RETVAL = THIS->x; %};
     long y()
         %code{% RETVAL = THIS->y; %};
+    void set_x(long val)
+        %code{% THIS->x = val; %};
+    void set_y(long val)
+        %code{% THIS->y = val; %};
     int nearest_point_index(Points points);
     Point* nearest_point(Points points)
         %code{% RETVAL = new Point(); THIS->nearest_point(points, RETVAL); %};