Bugfix: recent changes broke the "Infill every N layers" feature

lib/Slic3r/Fill.pm

@@ -8,6 +8,7 @@ use Slic3r::Fill::HilbertCurve;
 use Slic3r::Fill::OctagramSpiral;
 use Slic3r::Fill::Rectilinear;
 use Slic3r::Fill::Rectilinear2;
+use Slic3r::Geometry qw(shortest_path);
 
 use XXX;
 
@@ -40,7 +41,19 @@ sub make_fill {
     }
     
     printf "Filling layer %d:\n", $layer->id;
+    
+    # organize $layer->fill_surfaces using a shortest path search
+    @{ $layer->fill_surfaces } = @{shortest_path([
+        map [ $_->[0]->contour->points->[0], $_ ], grep @$_, @{ $layer->fill_surfaces },
+    ])};
+    
     foreach my $surfaces (@{ $layer->fill_surfaces }) {
+    
+        # organize $surfaces using a shortest path search
+        @$surfaces = @{shortest_path([
+            map [ $_->contour->points->[0], $_ ], @$surfaces,
+        ])};
+    
         SURFACE: foreach my $surface (@$surfaces) {
             Slic3r::debugf " Processing surface %s:\n", $surface->id;
             

lib/Slic3r/Geometry/Clipper.pm

@@ -31,11 +31,14 @@ sub diff_ex {
     $clipper->clear;
     $clipper->add_subject_polygons($subject);
     $clipper->add_clip_polygons($clip);
-    return $clipper->ex_execute(CT_DIFFERENCE, PFT_NONZERO, PFT_NONZERO);
+    return [
+        map Slic3r::ExPolygon->new($_),
+            @{ $clipper->ex_execute(CT_DIFFERENCE, PFT_NONZERO, PFT_NONZERO) },
+    ];
 }
 
 sub diff {
-    return [ map { $_->{outer}, $_->{holes} } diff_ex(@_) ];
+    return [ map @$_, diff_ex(@_) ];
 }
 
 sub union_ex {

lib/Slic3r/Print.pm

@@ -365,6 +365,7 @@ sub infill_every_layers {
                     [ map $_->p, grep $_->surface_type eq 'internal', @$surfaces ],
                 );
                 next if !@$intersection;
+                my $intersection_offsetted = safety_offset([ map @$_, @$intersection ]);
                 
                 # new fill surfaces of the current layer are:
                 # - any non-internal surface
@@ -387,7 +388,7 @@ sub infill_every_layers {
                                     map $_->p, grep $_->surface_type eq 'internal' && $_->depth_layers == $depth, 
                                         @$surfaces,
                                 ],
-                                safety_offset($intersection),
+                                $intersection_offsetted,
                             )};
                     }
                     @$surfaces = @new_surfaces;
@@ -408,7 +409,7 @@ sub infill_every_layers {
                                     map $_->p, grep $_->surface_type eq 'internal' && $_->depth_layers == $depth, 
                                         @$lower_surfaces,
                                 ],
-                                safety_offset($intersection),
+                                $intersection_offsetted,
                             )};
                     }
                     @$lower_surfaces = @new_surfaces;