Always fix self-intersecting polygons that Douglas-Peucker might return

lib/Slic3r/ExPolygon.pm

@@ -172,8 +172,13 @@ sub clip_line {
 
 sub simplify {
     my $self = shift;
-    $_->simplify(@_) for @$self;
+    my ($tolerance) = @_;
-    $self;
+    
+    # it would be nice to have a multilinestring_simplify method in B::G::U
+    my @simplified = Slic3r::Geometry::Clipper::simplify_polygons(
+        [ map Boost::Geometry::Utils::linestring_simplify($_, $tolerance), @$self ],
+    );
+    return @{ Slic3r::Geometry::Clipper::union_ex([ @simplified ]) };
 }
 
 sub scale {

lib/Slic3r/ExtrusionPath.pm

@@ -81,6 +81,11 @@ sub clip_with_expolygon {
     return @paths;
 }
 
+sub simplify {
+    my $self = shift;
+    $self->polyline($self->polyline->simplify(@_));
+}
+
 sub points {
     my $self = shift;
     return $self->polyline;

lib/Slic3r/GCode/MotionPlanner.pm

@@ -56,22 +56,20 @@ sub BUILD {
         }
     };
     
+    # simplify islands
+    @{$self->islands} = map $_->simplify($self->_inner_margin), @{$self->islands};
+    
     # process individual islands
     for my $i (0 .. $#{$self->islands}) {        
-        # simplify the island's contours
-        $self->islands->[$i]->simplify($self->_inner_margin);
-        
         # offset the island inwards to make the boundaries for internal movements
         # so that no motion along external perimeters happens
-        $self->_inner->[$i] = [ $self->islands->[$i]->offset_ex(-$self->_inner_margin) ]
+        $self->_inner->[$i] = $self->no_internal
-            if !$self->no_internal;
+            ? []
+            : [ $self->islands->[$i]->offset_ex(-$self->_inner_margin) ];
         
         # offset the island outwards to make the boundaries for external movements
         $self->_outer->[$i] = [ $self->islands->[$i]->contour->offset($self->_outer_margin) ];
         
-        # further simplification (isn't this a duplication of the one above?)
-        $_->simplify($self->_inner_margin) for @{$self->_inner->[$i]}, @{$self->_outer->[$i]};
-        
         # if internal motion is enabled, build a set of utility expolygons representing
         # the outer boundaries (as contours) and the inner boundaries (as holes). whenever
         # we jump from a hole to a contour or viceversa, we know we're crossing a perimeter

lib/Slic3r/GUI/Plater.pm

@@ -1137,9 +1137,8 @@ sub make_thumbnail {
     for (map @$_, map @$_, @{$thumbnail->expolygons}) {
         @$_ = map $_ * $self->thumbnail_scaling_factor, @$_;
     }
+    @{$thumbnail->expolygons} = map $_->simplify(0.5), grep $_->area >= 1, @{$thumbnail->expolygons};
     foreach my $expolygon (@{$thumbnail->expolygons}) {
-    	@$expolygon = grep $_->area >= 1, @$expolygon;
-	    $expolygon->simplify(0.5);
     	$expolygon->rotate(Slic3r::Geometry::deg2rad($self->rotate));
     	$expolygon->scale($self->scale);
     }

lib/Slic3r/Geometry.pm

@@ -12,7 +12,7 @@ our @EXPORT_OK = qw(
     point_is_on_left_of_segment polyline_lines polygon_lines nearest_point
     point_along_segment polygon_segment_having_point polygon_has_subsegment
     polygon_has_vertex polyline_length can_connect_points deg2rad rad2deg
-    rotate_points move_points remove_coinciding_points clip_segment_polygon
+    rotate_points move_points clip_segment_polygon
     sum_vectors multiply_vector subtract_vectors dot perp polygon_points_visibility
     line_intersection bounding_box bounding_box_intersect same_point same_line
     longest_segment angle3points three_points_aligned line_direction
@@ -375,15 +375,6 @@ sub move_points {
     return map Slic3r::Point->new($shift->[X] + $_->[X], $shift->[Y] + $_->[Y]), @points;
 }
 
-# preserves order
-sub remove_coinciding_points {
-    my ($points) = @_;
-    
-    my %p = map { sprintf('%f,%f', @$_) => "$_" } @$points;
-    %p = reverse %p;
-    @$points = grep $p{"$_"}, @$points;
-}
-
 # implementation of Liang-Barsky algorithm
 # polygon must be convex and ccw
 sub clip_segment_polygon {

lib/Slic3r/Geometry/Clipper.pm

@@ -92,4 +92,14 @@ sub collapse_ex {
     return union_ex([@result]);
 }
 
+sub simplify_polygon {
+    my ($polygon, $pft) = @_;
+    return @{ Math::Clipper::simplify_polygon($polygon, $pft // PFT_NONZERO) };
+}
+
+sub simplify_polygons {
+    my ($polygons, $pft) = @_;
+    return @{ Math::Clipper::simplify_polygons($polygons, $pft // PFT_NONZERO) };
+}
+
 1;

lib/Slic3r/Layer/Region.pm

@@ -263,14 +263,14 @@ sub make_perimeters {
             # we offset by half the perimeter spacing (to get to the actual infill boundary)
             # and then we offset back and forth by the infill spacing to only consider the
             # non-collapsing regions
-            my @fill_boundaries = @{union_ex([
+            push @{ $self->fill_surfaces },
+                map $_->simplify(&Slic3r::SCALED_RESOLUTION),
+                @{union_ex([
                     Slic3r::Geometry::Clipper::offset(
                         [Slic3r::Geometry::Clipper::offset([ map @$_, @last_offsets ], -($perimeter_spacing/2 + $infill_spacing))], 
                         +$infill_spacing,
                     ),
                 ])};
-            $_->simplify(&Slic3r::SCALED_RESOLUTION) for @fill_boundaries;
-            push @{ $self->fill_surfaces }, @fill_boundaries;
         }
         
         # fill gaps

lib/Slic3r/Polygon.pm

@@ -97,6 +97,11 @@ sub grow {
     return $self->split_at_first_point->grow(@_);
 }
 
+sub simplify {
+    my $self = shift;
+    return Slic3r::Geometry::Clipper::simplify_polygon( $self->SUPER::simplify(@_) );
+}
+
 # this method subdivides the polygon segments to that no one of them
 # is longer than the length provided
 sub subdivide {

lib/Slic3r/Polyline.pm

@@ -68,8 +68,8 @@ sub simplify {
     my $self = shift;
     my $tolerance = shift || 10;
     
-    @$self = @{ Boost::Geometry::Utils::linestring_simplify($self, $tolerance) };
+    my $simplified = Boost::Geometry::Utils::linestring_simplify($self, $tolerance);
-    bless $_, 'Slic3r::Point' for @$self;
+    return (ref $self)->new($simplified);
 }
 
 sub reverse {

lib/Slic3r/Print.pm

@@ -335,8 +335,8 @@ sub export_gcode {
     # simplify slices (both layer and region slices),
     # we only need the max resolution for perimeters
     foreach my $layer (map @{$_->layers}, @{$self->objects}) {
-        $_->simplify(&Slic3r::SCALED_RESOLUTION)
+        @$_ = map $_->simplify(&Slic3r::SCALED_RESOLUTION), @$_
-            for @{$layer->slices}, (map $_->expolygon, map @{$_->slices}, @{$layer->regions});
+            for $layer->slices, (map $_->slices, @{$layer->regions});
     }
     
     # this will assign a type (top/bottom/internal) to $layerm->slices

lib/Slic3r/Print/Object.pm

@@ -774,8 +774,10 @@ sub generate_support_material {
                 [ map @$_, @{ $upper_layers_overhangs[-1] || [] } ],
                 [ map @$_, @current_layer_offsetted_slices ],
             );
-            $layers_contact_areas{$i} = collapse_ex([ map @$_, @{$layers_contact_areas{$i}} ], $flow->scaled_width);
+            $layers_contact_areas{$i} = [
-            $_->simplify($flow->scaled_spacing) for @{$layers_contact_areas{$i}};
+                map $_->simplify($flow->scaled_spacing), 
+                    collapse_ex([ map @$_, @{$layers_contact_areas{$i}} ], $flow->scaled_width),
+            ];
             
             # to define interface regions of this layer we consider the overhangs of all the upper layers
             # minus the first one
@@ -786,8 +788,10 @@ sub generate_support_material {
                     (map @$_, @{ $layers_contact_areas{$i} }),
                 ],
             );
-            $layers_interfaces{$i} = collapse_ex([ map @$_, @{$layers_interfaces{$i}} ], $flow->scaled_width);
+            $layers_interfaces{$i} = [
-            $_->simplify($flow->scaled_spacing) for @{$layers_interfaces{$i}};
+                map $_->simplify($flow->scaled_spacing), 
+                    collapse_ex([ map @$_, @{$layers_interfaces{$i}} ], $flow->scaled_width),
+            ];
             
             # generate support material in current layer (for upper layers)
             @current_support_regions = @{diff_ex(
@@ -806,8 +810,10 @@ sub generate_support_material {
                     (map @$_, @{ $layers_interfaces{$i} }),
                 ],
             );
-            $layers{$i} = collapse_ex([ map @$_, @{$layers{$i}} ], $flow->scaled_width);
+            $layers{$i} = [
-            $_->simplify($flow->scaled_spacing) for @{$layers{$i}};
+                map $_->simplify($flow->scaled_spacing), 
+                    collapse_ex([ map @$_, @{$layers{$i}} ], $flow->scaled_width),
+            ];
             
             # get layer overhangs and put them into queue for adding support inside lower layers;
             # we need an angle threshold for this

lib/Slic3r/Surface.pm

@@ -81,12 +81,22 @@ sub group {
 
 sub offset {
     my $self = shift;
-    return map {
+    return map $self->_inflate_expolygon($_), $self->expolygon->offset_ex(@_);
-        (ref $self)->new(
+}
-            expolygon => $_,
+
+sub simplify {
+    my $self = shift;
+    return map $self->_inflate_expolygon($_), $self->expolygon->simplify(@_);
+}
+
+sub _inflate_expolygon {
+    my $self = shift;
+    my ($expolygon) = @_;
+    
+    return (ref $self)->new(
+        expolygon => $expolygon,
         map { $_ => $self->$_ } qw(surface_type depth_layers bridge_angle),
-        )
+    );
-    } $self->expolygon->offset_ex(@_);
 }
 
 sub clipper_polygon {

t/clean_polylines.t

@@ -2,7 +2,7 @@ use Test::More;
 use strict;
 use warnings;
 
-plan tests => 6;
+plan tests => 7;
 
 BEGIN {
     use FindBin;
@@ -24,7 +24,7 @@ use Slic3r;
     my $polyline = Slic3r::Polyline->new([
         [0,0],[1,0],[2,0],[2,1],[2,2],[1,2],[0,2],[0,1],[0,0],
     ]);
-    $polyline->simplify(1);
+    $polyline = $polyline->simplify(1);
     is_deeply $polyline, [ [0, 0], [2, 0], [2, 2], [0, 2], [0, 0] ], 'Douglas-Peucker';
 }
 
@@ -33,7 +33,7 @@ use Slic3r;
         [0,0],[0.5,0.5],[1,0],[1.25,-0.25],[1.5,.5],
     ]);
     $polyline->scale(100);
-    $polyline->simplify(25);
+    $polyline = $polyline->simplify(25);
     is_deeply $polyline, [ [0, 0], [50, 50], [125, -25], [150, 50] ], 'Douglas-Peucker';
 }
 
@@ -75,9 +75,10 @@ use Slic3r;
     ok @$polygon < @$gear, 'gear was simplified using merge_continuous_lines';
 
     my $num_points = scalar @$polygon;
-    $polygon->simplify;
+    my @simplified = $polygon->simplify;
-    note sprintf "original points: %d\nnew points: %d", $num_points, scalar(@$polygon);
+    ok @simplified == 1, 'gear simplified to a single polygon';
-    ok @$polygon < $num_points, 'gear was further simplified using Douglas-Peucker';
+    note sprintf "original points: %d\nnew points: %d", $num_points, scalar(@{$simplified[0]});
+    ok @{$simplified[0]} < $num_points, 'gear was further simplified using Douglas-Peucker';
 }
 
 {

t/combineinfill.t

@@ -43,8 +43,8 @@ use Slic3r::Test;
         $_->slice(keep_meshes => 1) for @{$self->objects};
         $_->make_perimeters for @{$self->objects};
         foreach my $layer (map @{$_->layers}, @{$self->objects}) {
-            $_->simplify(&Slic3r::SCALED_RESOLUTION)
+            @$_ = map $_->simplify(&Slic3r::SCALED_RESOLUTION), @$_
-                for @{$layer->slices}, (map $_->expolygon, map @{$_->slices}, @{$layer->regions});
+                for $layer->slices, (map $_->slices, @{$layer->regions});
         }
         $_->detect_surfaces_type for @{$self->objects};
         $_->prepare_fill_surfaces for map @{$_->regions}, map @{$_->layers}, @{$self->objects};