Detection of optimal infill direction for bridges. Includes many fixes and improvements.

README.markdown

@@ -41,6 +41,8 @@ Slic3r current features are:
 * skirt (with rounded corners);
 * use relative or absolute extrusion commands;
 * high-res perimeters (like the "Skin" plugin for Skeinforge);
+* detect optimal infill direction for bridges;
+* save configuration profiles;
 * center print around bed center point;
 * multiple solid layers near horizontal external surfaces;
 * ability to scale, rotate and multiply input object;
@@ -51,10 +53,8 @@ Roadmap includes the following goals:
 * output some statistics;
 * allow the user to customize initial and final GCODE commands;
 * support material for internal perimeters;
-* detect optimal infill direction for bridges;
 * cool;
-* other fill patterns;
+* other fill patterns.
-* nice packaging for cross-platform deployment.
 
 ## Is it usable already?
 

lib/Slic3r.pm

@@ -26,6 +26,7 @@ use Slic3r::Print;
 use Slic3r::Skein;
 use Slic3r::STL;
 use Slic3r::Surface;
+use Slic3r::Surface::Bridge;
 use Slic3r::Surface::Collection;
 
 # printer options

lib/Slic3r/Fill.pm

@@ -5,6 +5,8 @@ use Slic3r::Fill::Base;
 use Slic3r::Fill::Rectilinear;
 use Slic3r::Fill::Rectilinear2;
 
+use XXX;
+
 has 'print'     => (is => 'ro', required => 1);
 has 'fillers'   => (is => 'rw', default => sub { {} });
 

lib/Slic3r/Fill/Base.pm

@@ -10,7 +10,7 @@ use constant PI => 4 * atan2(1, 1);
 
 sub infill_direction {
     my $self = shift;
-    my ($polygons) = @_;
+    my ($surface) = @_;
     
     # set infill angle
     my (@rotate, @shift);
@@ -23,7 +23,11 @@ sub infill_direction {
         $rotate[0] = Slic3r::Geometry::deg2rad($Slic3r::fill_angle) + PI/2;
     }
     
-    # TODO: here we should implement an "infill in direction of bridges" option
+    # use bridge angle
+    if ($surface->isa('Slic3r::Surface::Bridge')) {
+        Slic3r::debugf "Filling bridge with angle %d\n", $surface->bridge_angle;
+        $rotate[0] = Slic3r::Geometry::deg2rad($surface->bridge_angle);
+    }
     
     @shift = @{ +(Slic3r::Geometry::rotate_points(@rotate, \@shift))[0] };
     return [\@rotate, \@shift];

lib/Slic3r/Fill/Rectilinear.pm

@@ -16,7 +16,7 @@ sub fill_surface {
     
     # rotate polygons so that we can work with vertical lines here
     my $polygons = [ $surface->p ];
-    my $rotate_vector = $self->infill_direction($polygons);
+    my $rotate_vector = $self->infill_direction($surface);
     $self->rotate_points($polygons, $rotate_vector);
     
     my $bounding_box = [ Slic3r::Geometry::bounding_box(map @$_, $polygons) ];

lib/Slic3r/Fill/Rectilinear2.pm

@@ -21,7 +21,7 @@ sub fill_surface {
     my $polygons = [ $surface->p ];
     
     # rotate polygons so that we can work with vertical lines here
-    my $rotate_vector = $self->infill_direction($polygons);
+    my $rotate_vector = $self->infill_direction($surface);
     $self->rotate_points($polygons, $rotate_vector);
     
     my $distance_between_lines = $Slic3r::flow_width / $Slic3r::resolution / $params{density};

lib/Slic3r/Geometry.pm

@@ -10,9 +10,11 @@ use constant A => 0;
 use constant B => 1;
 use constant X => 0;
 use constant Y => 1;
-use constant epsilon => 1E-4;
 our $parallel_degrees_limit = abs(deg2rad(3));
 
+our $epsilon = 1E-4;
+sub epsilon () { $epsilon }
+
 sub slope {
     my ($line) = @_;
     return undef if abs($line->[B][X] - $line->[A][X]) < epsilon;  # line is vertical
@@ -60,6 +62,16 @@ sub distance_between_points {
     return sqrt((($p1->[X] - $p2->[X])**2) + ($p1->[Y] - $p2->[Y])**2);
 }
 
+sub line_length {
+    my ($line) = @_;
+    return distance_between_points(@$line[A, B]);
+}
+
+sub midpoint {
+    my ($line) = @_;
+    return [ ($line->[B][X] + $line->[A][X]) / 2, ($line->[B][Y] + $line->[A][Y]) / 2 ];
+}
+
 sub point_in_polygon {
     my ($point, $polygon) = @_;
     
@@ -118,6 +130,13 @@ sub point_in_segment {
     return abs($y3 - $y) < epsilon ? 1 : 0;
 }
 
+sub segment_in_segment {
+    my ($needle, $haystack) = @_;
+    
+    # a segment is contained in another segment if its endpoints are contained
+    return point_in_segment($needle->[A], $haystack) && point_in_segment($needle->[B], $haystack);
+}
+
 sub point_is_on_left_of_segment {
     my ($point, $line) = @_;
     
@@ -125,19 +144,24 @@ sub point_is_on_left_of_segment {
         - ($line->[B][Y] - $line->[A][Y])*($point->[X] - $line->[A][X])) > 0;
 }
 
-sub polygon_lines {
+sub polyline_lines {
     my ($polygon) = @_;
     
     my @lines = ();
-    my $last_point = $polygon->[-1];
+    my $last_point;
     foreach my $point (@$polygon) {
-        push @lines, [ $last_point, $point ];
+        push @lines, [ $last_point, $point ] if $last_point;
         $last_point = $point;
     }
     
     return @lines;
 }
 
+sub polygon_lines {
+    my ($polygon) = @_;
+    return polyline_lines([ @$polygon, $polygon->[0] ]);
+}
+
 sub nearest_point {
     my ($point, $points) = @_;
     
@@ -179,6 +203,30 @@ sub polygon_segment_having_point {
     return undef;
 }
 
+# return true if the given segment is contained in any edge of the polygon
+sub polygon_has_subsegment {
+    my ($polygon, $segment) = @_;
+    foreach my $line (polygon_lines($polygon)) {
+        return 1 if segment_in_segment($segment, $line);
+    }
+    return 0;
+}
+
+sub polygon_has_vertex {
+    my ($polygon, $point) = @_;
+    foreach my $p (@$polygon) {
+        return 1 if points_coincide($p, $point);
+    }
+    return 0;
+}
+
+sub polyline_length {
+    my ($polyline) = @_;
+    my $length = 0;
+    $length += line_length($_) for polygon_lines($polyline);
+    return $length;
+}
+
 sub can_connect_points {
     my ($p1, $p2, $polygons) = @_;
     
@@ -207,6 +255,11 @@ sub deg2rad {
     return PI() * $degrees / 180;
 }
 
+sub rad2deg {
+    my ($rad) = @_;
+    return $rad / PI() * 180;
+}
+
 sub rotate_points {
     my ($radians, $center, @points) = @_;
     $center ||= [0,0];

lib/Slic3r/Layer.pm

@@ -2,8 +2,11 @@ package Slic3r::Layer;
 use Moo;
 
 use Math::Clipper ':all';
+use Math::ConvexHull qw(convex_hull);
 use XXX;
 
+use constant PI => 4 * atan2(1, 1);
+
 # a sequential number of layer, starting at 0
 has 'id' => (
     is          => 'ro',
@@ -26,17 +29,31 @@ has 'surfaces' => (
     default => sub { [] },
 );
 
+# collection of surfaces representing bridges
+has 'bridges' => (
+    is      => 'rw',
+    #isa     => 'ArrayRef[Slic3r::Surface::Bridge]',
+    default => sub { [] },
+);
+
+# collection of surfaces to make perimeters for
+has 'perimeter_surfaces' => (
+    is      => 'rw',
+    #isa     => 'ArrayRef[Slic3r::Surface]',
+    default => sub { [] },
+);
+
 # ordered collection of extrusion paths to build all perimeters
 has 'perimeters' => (
     is      => 'rw',
-    #isa     => 'ArrayRef[Slic3r::ExtrusionPath]',
+    #isa     => 'ArrayRef[Slic3r::ExtrusionLoop]',
     default => sub { [] },
 );
 
 # ordered collection of extrusion paths to build skirt loops
 has 'skirts' => (
     is      => 'rw',
-    #isa     => 'ArrayRef[Slic3r::ExtrusionPath]',
+    #isa     => 'ArrayRef[Slic3r::ExtrusionLoop]',
     default => sub { [] },
 );
 
@@ -44,7 +61,7 @@ has 'skirts' => (
 # they represent boundaries of areas to fill
 has 'fill_surfaces' => (
     is      => 'rw',
-    #isa     => 'ArrayRef[Slic3r::Surface]',
+    #isa     => 'ArrayRef[Slic3r::Surface::Collection]',
     default => sub { [] },
 );
 
@@ -101,18 +118,34 @@ sub remove_surface {
 }
 
 # build polylines of lines which do not already belong to a surface
+# okay, this code is a mess.  will need some refactoring.  sorry.
 sub make_polylines {
     my $self = shift;
     
     # remove line duplicates
-    {
+    if (0) {
+        # this removes any couple of coinciding Slic3r::Line::FacetEdge
+        my %lines_map = ();
+        foreach my $line (grep $_->isa('Slic3r::Line::FacetEdge'), @{ $self->lines }) {
+            my $ordered_id = $line->ordered_id;
+            if (exists $lines_map{$ordered_id}) {
+                delete $lines_map{$ordered_id};
+                next;
+            }
+            $lines_map{$ordered_id} = $line;
+        }
+        
+        @{ $self->lines } = (values(%lines_map), grep !$_->isa('Slic3r::Line::FacetEdge'), @{ $self->lines });
+    }
+    if (1) {
+        # this removes any duplicate, leaving one
         my %lines_map = map { join(',', sort map $_->id, @{$_->points} ) => "$_" } @{ $self->lines };
         %lines_map = reverse %lines_map;
         @{ $self->lines } = grep $lines_map{"$_"}, @{ $self->lines };
     }
     
     # now remove lines that are already part of a surface
-    {
+    if (1) {
         my @lines = @{ $self->lines };
         @{ $self->lines } = ();
         LINE: foreach my $line (@lines) {
@@ -130,26 +163,31 @@ sub make_polylines {
     }
     
     # make a cache of line endpoints
-    my %pointmap = ();
+    my (%pointmap) = ();
     foreach my $line (@{ $self->lines }) {
         for my $point (@{ $line->points }) {
             $pointmap{$point->id} ||= [];
             push @{ $pointmap{$point->id} }, $line;
         }
     }
-    
+    foreach my $point_id (keys %pointmap) {
-    # defensive programming
+        $pointmap{$point_id} = [
-    #die "No point should be endpoint of less or more than 2 lines!"
+            sort { $a->isa('Slic3r::Line::FacetEdge') <=> $b->isa('Slic3r::Line::FacetEdge') } 
-    #    if grep @$_ != 2, values %pointmap;
+                @{$pointmap{$point_id}} ];
+    }
     
     if (0) {
         # defensive programming
         for (keys %pointmap) {
             next if @{$pointmap{$_}} == 2;
             
-            #use Slic3r::SVG;
+            use Slic3r::SVG;
-            #Slic3r::SVG::output_points($main::print, "points.svg", [ map [split /,/], keys %pointmap ], [ [split /,/, $_ ] ]);
+            Slic3r::SVG::output(undef, "lines_and_points.svg",
-            #Slic3r::SVG::output_lines($main::print, "lines.svg", [ map $_->p, @{$self->lines} ]);
+                lines       => [ map $_->p, grep !$_->isa('Slic3r::Line::FacetEdge'), @{$self->lines} ],
+                red_lines   => [ map $_->p, grep $_->isa('Slic3r::Line::FacetEdge'), @{$self->lines} ],
+                points      => [ map [split /,/], keys %pointmap ],
+                red_points  => [ [split /,/, $_ ] ],
+            );
             
             YYY $pointmap{$_};
             
@@ -198,6 +236,11 @@ sub make_polylines {
         # remove last point as it coincides with first one
         pop @$points;
         
+        if (@$points == 1 && $first_line->isa('Slic3r::Line::FacetEdge')) {
+            Slic3r::debugf "Skipping spare facet edge";
+            next;
+        }
+        
         die sprintf "Invalid polyline with only %d points\n", scalar(@$points) if @$points < 3;
         
         Slic3r::debugf "Discovered polyline of %d points (%s)\n", scalar @$points,
@@ -336,6 +379,21 @@ sub merge_contiguous_surfaces {
         $resulting_surfaces{$type} = $result2;
     }
     
+    # remove overlapping surfaces
+    # (remove anything that is not internal from areas covered by internal surfaces)
+    # this may happen because of rounding of Z coordinates: the model could have
+    # features smaller than our layer height, so we'd get more things on a single
+    # layer
+    if (0) {  # not proven to be necessary until now
+        my $clipper = Math::Clipper->new;
+        foreach my $type (qw(bottom top)) {
+            $clipper->clear;
+            $clipper->add_subject_polygons([ map { $_->{outer}, @{$_->{holes}} } @{$resulting_surfaces{$type}} ]);
+            $clipper->add_clip_polygons([ map { $_->{outer}, @{$_->{holes}} } @{$resulting_surfaces{internal}} ]);
+            $resulting_surfaces{$type} = $clipper->ex_execute(CT_DIFFERENCE, PFT_NONZERO, PFT_NONZERO);
+        }
+    }
+    
     # save surfaces
     @{ $self->surfaces } = ();
     foreach my $type (keys %resulting_surfaces) {
@@ -357,23 +415,181 @@ sub merge_contiguous_surfaces {
     }
 }
 
-sub remove_small_features {
+sub remove_small_surfaces {
     my $self = shift;
+    my @good_surfaces = ();
     
-    # for each perimeter, try to get an inwards offset
+    foreach my $surface (@{$self->surfaces}) {
-    # for a distance equal to half of the extrusion width;
+        next if !$surface->contour->is_printable;
-    # if no offset is possible, then feature is not printable
+        @{$surface->holes} = grep $_->is_printable, @{$surface->holes};
-    my @good_perimeters = ();
+        push @good_surfaces, $surface;
-    foreach my $loop (@{$self->perimeters}) {
-        my $p = $loop->p;
-        @$p = reverse @$p if !is_counter_clockwise($p);
-        my $offsets = offset([$p], -($Slic3r::flow_width / 2 / $Slic3r::resolution), $Slic3r::resolution * 100000, JT_MITER, 2);
-        push @good_perimeters, $loop if @$offsets;
     }
+    
+    @{$self->surfaces} = @good_surfaces;
+}
+
+sub remove_small_perimeters {
+    my $self = shift;
+    my @good_perimeters = grep $_->is_printable, @{$self->perimeters};
     Slic3r::debugf "removed %d unprintable perimeters\n", (@{$self->perimeters} - @good_perimeters) 
         if @good_perimeters != @{$self->perimeters};
     
     @{$self->perimeters} = @good_perimeters;
 }
 
+# make bridges printable
+sub process_bridges {
+    my $self = shift;
+    return if $self->id == 0;
+    
+    # a bottom surface on a layer > 0 is either a bridge or a overhang 
+    # or a combination of both
+    
+    my @bottom_surfaces     = grep $_->surface_type eq 'bottom',   @{$self->surfaces} or return;
+    my @supporting_surfaces = grep $_->surface_type =~ /internal/, @{$self->surfaces};
+    
+    SURFACE: foreach my $surface (@bottom_surfaces) {
+        # since we can't print concave bridges, we transform the surface
+        # in a convex polygon; this will print thin membranes eventually
+        my $surface_p = convex_hull($surface->contour->p);
+        
+        # find all supported edges (as polylines, thus keeping notion of 
+        # consecutive supported edges)
+        my @supported_polylines = ();
+        {
+            my @current_polyline = ();
+            EDGE: foreach my $edge (Slic3r::Geometry::polygon_lines($surface_p)) {
+                for (@supporting_surfaces) {
+                    local $Slic3r::Geometry::epsilon = 1E+7;
+                    if (Slic3r::Geometry::polygon_has_subsegment($_->contour->p, $edge)) {
+                        push @current_polyline, $edge;
+                        next EDGE;
+                    }
+                }
+                if (@current_polyline) {
+                    push @supported_polylines, [@current_polyline];
+                    @current_polyline = ();
+                }
+            }
+            push @supported_polylines, [@current_polyline] if @current_polyline;
+        }
+        
+        # defensive programming, this shouldn't happen
+        if (@supported_polylines == 0) {
+            Slic3r::debugf "Found bridge/overhang with no supports on layer %d; ignoring\n", $self->id;
+            next SURFACE;
+        }
+        
+        if (@supported_polylines == 1) {
+            Slic3r::debugf "Found bridge/overhang with only one support on layer %d; ignoring\n", $self->id;
+            next SURFACE;
+        }
+        
+        # now connect the first point to the last of each polyline
+        @supported_polylines = map [ $_->[0]->[0], $_->[-1]->[-1] ], @supported_polylines;
+        
+        # if we got more than two supports, get the longest two
+        if (@supported_polylines > 2) {
+            my %lengths = map { "$_" => Slic3r::Geometry::line_length($_) }, @supported_polylines;
+            @supported_polylines = sort { $lengths{"$a"} <=> $lengths{"$b"} } @supported_polylines;
+            @supported_polylines = @supported_polylines[0,1];
+        }
+        
+        # connect the midpoints, that will give the the optimal infill direction
+        my @midpoints = map Slic3r::Geometry::midpoint($_), @supported_polylines;
+        my $bridge_angle = -Slic3r::Geometry::rad2deg(Slic3r::Geometry::line_atan(\@midpoints) + PI/2);
+        Slic3r::debugf "Optimal infill angle of bridge on layer %d is %d degrees\n", $self->id, $bridge_angle;
+        
+        # detect which neighbor surfaces are now supporting our bridge
+        my @supporting_neighbor_surfaces = ();
+        foreach my $supporting_surface (@supporting_surfaces) {
+            local $Slic3r::Geometry::epsilon = 1E+7;
+            push @supporting_neighbor_surfaces, $supporting_surface 
+                if grep Slic3r::Geometry::polygon_has_vertex($supporting_surface->contour->p, $_), 
+                    map $_->[0], @supported_polylines;
+        }
+        
+        # defensive programming, this shouldn't happen
+        if (@supporting_neighbor_surfaces == 0) {
+            Slic3r::debugf "Couldn't find supporting surfaces on layer %d; ignoring\n", $self->id;
+            next SURFACE;
+        }
+        
+        # now, extend our bridge by taking a portion of supporting surfaces
+        {
+            # offset the bridge by 5mm
+            my $bridge_offset = ${ offset([$surface_p], 5 / $Slic3r::resolution, $Slic3r::resolution * 100, JT_MITER, 2) }[0];
+            
+            # calculate the new bridge
+            my $clipper = Math::Clipper->new;
+            $clipper->add_subject_polygon($surface_p);
+            $clipper->add_subject_polygons([ map $_->p, @supporting_neighbor_surfaces ]);
+            $clipper->add_clip_polygon($bridge_offset);
+            my $intersection = $clipper->execute(CT_INTERSECTION, PFT_NONZERO, PFT_NONZERO);
+            
+            push @{$self->bridges}, map Slic3r::Surface::Bridge->cast_from_polygon($_,
+                surface_type => 'bottom',
+                bridge_angle => $bridge_angle,
+            ), @$intersection;
+        }
+    }
+}
+
+# generates a set of surfaces that will be used to make perimeters
+# thus, we need to merge internal surfaces and bridges
+sub detect_perimeter_surfaces {
+    my $self = shift;
+    
+    # little optimization: skip the Clipper UNION if we have no bridges
+    if (!@{$self->bridges}) {
+        push @{$self->perimeter_surfaces}, @{$self->surfaces};
+    } else {
+        my $clipper = Math::Clipper->new;
+        $clipper->add_subject_polygons([ map $_->p, grep $_->surface_type =~ /internal/, @{$self->surfaces} ]);
+        $clipper->add_clip_polygons([ map $_->p, @{$self->bridges} ]);
+        my $union = $clipper->ex_execute(CT_UNION, PFT_NONZERO, PFT_NONZERO);
+        
+        push @{$self->perimeter_surfaces}, 
+            map Slic3r::Surface->cast_from_expolygon($_, surface_type => 'internal'), 
+            @$union;
+        
+        push @{$self->perimeter_surfaces}, 
+            grep $_->surface_type !~ /internal/ && ($_->surface_type ne 'bottom' || $self->id == 0), 
+            @{$self->surfaces};
+    }
+}
+
+# splits fill_surfaces in internal and bridge surfaces
+sub split_bridges_fills {
+    my $self = shift;
+    
+    my $clipper = Math::Clipper->new;
+    foreach my $surf_coll (@{$self->fill_surfaces}) {
+        my @surfaces = @{$surf_coll->surfaces};
+        @{$surf_coll->surfaces} = ();
+        
+        # intersect fill_surfaces with bridges to get actual bridges
+        foreach my $bridge (@{$self->bridges}) {
+            $clipper->clear;
+            $clipper->add_subject_polygons([ map $_->p, @surfaces ]);
+            $clipper->add_clip_polygon($bridge->contour->p);
+            my $intersection = $clipper->ex_execute(CT_INTERSECTION, PFT_NONZERO, PFT_NONZERO);
+            push @{$surf_coll->surfaces}, map Slic3r::Surface::Bridge->cast_from_expolygon($_,
+                surface_type => 'bottom',
+                bridge_angle => $bridge->bridge_angle,
+            ), @$intersection;
+        }
+        
+        # difference between fill_surfaces and bridges are the other surfaces
+        foreach my $surface (@surfaces) {
+            $clipper->clear;
+            $clipper->add_subject_polygons([ $surface->p ]);
+            $clipper->add_clip_polygons([ map $_->contour->p, @{$self->bridges} ]);
+            my $difference = $clipper->ex_execute(CT_DIFFERENCE, PFT_NONZERO, PFT_NONZERO);
+            push @{$surf_coll->surfaces}, map Slic3r::Surface->cast_from_expolygon($_,
+                surface_type => $surface->surface_type), @$difference;
+        }
+    }
+}
+
 1;

lib/Slic3r/Line.pm

@@ -27,6 +27,11 @@ sub id {
     return $self->a->id . "-" . $self->b->id;
 }
 
+sub ordered_id {
+    my $self = shift;
+    return join('-', sort map $_->id, @{$self->points});
+}
+
 sub coordinates {
     my $self = shift;
     return ($self->a->coordinates, $self->b->coordinates);

lib/Slic3r/Perimeter.pm

@@ -18,7 +18,7 @@ sub make_perimeter {
         if $Slic3r::perimeter_offsets == 0;
     
     my (%contours, %holes) = ();
-    foreach my $surface (@{ $layer->surfaces }) {
+    foreach my $surface (@{ $layer->perimeter_surfaces }) {
         $contours{$surface} = [];
         $holes{$surface} = [];
         my @last_offsets = ();
@@ -47,17 +47,16 @@ sub make_perimeter {
         }
         
         # create one more offset to be used as boundary for fill
-        push @{ $layer->fill_surfaces }, Slic3r::Surface::Collection->new(
+        {
-            surfaces => [
+            my @fill_surfaces = map Slic3r::Surface->cast_from_expolygon(
-                map Slic3r::Surface->new(
+                $_,
-                    surface_type => $surface->surface_type,
+                surface_type => $surface->surface_type,
-                    contour      => Slic3r::Polyline::Closed->cast($_->{outer}),
+            ), map $self->offset_polygon($_), @last_offsets;
-                    holes        => [
+            
-                        map Slic3r::Polyline::Closed->cast($_), @{$_->{holes}}
+            push @{ $layer->fill_surfaces }, Slic3r::Surface::Collection->new(
-                    ],
+                surfaces => [@fill_surfaces],
-                ), map $self->offset_polygon($_), @last_offsets
+            ) if @fill_surfaces;
-            ],
+        }
-        );
     }
     
     # generate paths for holes:
@@ -91,15 +90,13 @@ sub make_perimeter {
 sub offset_polygon {
     my $self = shift;
     my ($polygon) = @_;
-    
-    my $distance = $Slic3r::flow_width / $Slic3r::resolution;
-    
     # $polygon holds a Math::Clipper ExPolygon hashref representing 
     # a polygon and its holes
-    my ($contour_p, @holes_p) = ($polygon->{outer}, @{$polygon->{holes}});
     
     # generate offsets
-    my $offsets = offset([ $contour_p, @holes_p ], -$distance, $Slic3r::resolution * 100000, JT_MITER, 2);
+    my $distance = $Slic3r::flow_width / $Slic3r::resolution;
+    my $offsets = offset([ $polygon->{outer}, @{$polygon->{holes}} ], -$distance, 
+        $Slic3r::resolution * 100000, JT_MITER, 2);
     
     # defensive programming
     my (@contour_offsets, @hole_offsets) = ();

lib/Slic3r/Polyline/Closed.pm

@@ -3,6 +3,8 @@ use Moo;
 
 extends 'Slic3r::Polyline';
 
+use Math::Clipper qw(JT_MITER);
+
 sub lines {
     my $self = shift;
     my @lines = $self->SUPER::lines(@_);
@@ -32,4 +34,17 @@ sub encloses_point {
     return Slic3r::Geometry::point_in_polygon($point->p, $self->p);
 }
 
+# returns false if the polyline is too tight to be printed
+sub is_printable {
+    my $self = shift;
+    
+    # try to get an inwards offset
+    # for a distance equal to half of the extrusion width;
+    # if no offset is possible, then polyline is not printable
+    my $p = $self->p;
+    @$p = reverse @$p if !Math::Clipper::is_counter_clockwise($p);
+    my $offsets = Math::Clipper::offset([$p], -($Slic3r::flow_width / 2 / $Slic3r::resolution), $Slic3r::resolution * 100000, JT_MITER, 2);
+    return @$offsets ? 1 : 0;
+}
+
 1;

lib/Slic3r/Print.pm

@@ -35,7 +35,7 @@ sub new_from_stl {
     print "\n==> PROCESSING SLICES:\n";
     foreach my $layer (@{ $print->layers }) {
         printf "\nProcessing layer %d:\n", $layer->id;
-    
+        
         # build polylines of lines which do not already belong to a surface
         my $polylines = $layer->make_polylines;
         
@@ -147,11 +147,22 @@ sub discover_horizontal_shells {
     }
 }
 
-# remove perimeters and fill surfaces which are too small to be extruded
+# remove surfaces which are too small to be extruded
-sub remove_small_features {
+sub remove_small_surfaces {
     my $self = shift;
-    
+    $_->remove_small_surfaces for @{$self->layers};
-    $_->remove_small_features for @{$self->layers};
+}
+
+# remove perimeters which are too small to be extruded
+sub remove_small_perimeters {
+    my $self = shift;
+    $_->remove_small_perimeters for @{$self->layers};
+}
+
+# make bridges printable
+sub process_bridges {
+    my $self = shift;
+    $_->process_bridges for @{ $self->layers };
 }
 
 sub extrude_perimeters {
@@ -160,12 +171,19 @@ sub extrude_perimeters {
     my $perimeter_extruder = Slic3r::Perimeter->new;
     
     foreach my $layer (@{ $self->layers }) {
+        $layer->detect_perimeter_surfaces;
         $perimeter_extruder->make_perimeter($layer);
         Slic3r::debugf "  generated paths: %s\n",
             join '  ', map $_->id, @{ $layer->perimeters } if $Slic3r::debug;
     }
 }
 
+# splits fill_surfaces in internal and bridge surfaces
+sub split_bridges_fills {
+    my $self = shift;
+    $_->split_bridges_fills for @{$self->layers};
+}
+
 sub extrude_fills {
     my $self = shift;
     

lib/Slic3r/STL.pm

@@ -80,8 +80,10 @@ sub parse_file {
             $vertex->[$_] = ($Slic3r::scale * $vertex->[$_] / $Slic3r::resolution) + $shift[$_]
                 for X,Y,Z;
             
-            # round Z coordinates; XY will be rounded automatically with coercion
+            # round Z coordinates to the nearest multiple of layer height
-            $vertex->[Z] = sprintf('%.0f', $vertex->[Z]);
+            # XY will be rounded automatically to integers with coercion
+            $vertex->[Z] = sprintf('%.0f', $vertex->[Z] * $Slic3r::resolution / $Slic3r::layer_height)
+                * $Slic3r::layer_height / $Slic3r::resolution;
         }
         
         foreach my $copy (@copies) {
@@ -92,7 +94,7 @@ sub parse_file {
             $self->_facet($print, $normal, @copy_vertices);
         }
     }
-        
+    
     return $print;
 }
 

lib/Slic3r/SVG.pm

@@ -22,14 +22,14 @@ sub output {
     
     my $svg = svg($print);
     
-    foreach my $type (qw(polygons polylines white_polygons red_polylines)) {
+    foreach my $type (qw(polygons polylines white_polygons red_polygons red_polylines)) {
         if ($things{$type}) {
             my $method = $type =~ /polygons/ ? 'polygon' : 'polyline';
             my $g = $svg->group(
                 style => {
                     'stroke-width' => 2,
                     'stroke' => $type =~ /red_/ ? 'red' : 'black',
-                    'fill' => $type eq 'polygons' ? 'grey' : 'none',
+                    'fill' => ($type !~ /polygons/ ? 'none' : ($type =~ /red_/ ? 'red' : 'grey')),
                 },
             );
             foreach my $polygon (@{$things{$type}}) {
@@ -51,7 +51,7 @@ sub output {
             my $g = $svg->group(
                 style => {
                     'stroke-width' => 2,
-                    'stroke' => 'black',
+                    'stroke' => $colour,
                     'fill' => $colour,
                 },
             );

lib/Slic3r/Skein.pm

@@ -14,16 +14,40 @@ sub go {
         if $self->input_file !~ /\.stl$/i;
     
     my $t0 = [gettimeofday];
-    my $print = Slic3r::Print->new_from_stl($self->input_file);
-    $print->extrude_perimeters;
-    $print->remove_small_features;
     
-    # detect which surfaces are near external layers
+    # skein the STL into layers
+    # each layer has surfaces with holes; surfaces are distinguished
+    # in top/bottom/internal
+    my $print = Slic3r::Print->new_from_stl($self->input_file);
+    
+    # this will remove unprintable surfaces
+    # (those that are too tight for extrusion)
+    $print->remove_small_surfaces;
+    
+    # make bridges printable
+    # this will add a set of bridges to each layer
+    $print->process_bridges;
+    
+    # make perimeters
+    # this will add a set of extrusion loops to each layer
+    # as well as a set of surfaces to be filled
+    $print->extrude_perimeters;
+    
+    # this will remove unprintable perimeter loops
+    # (those that are too tight for extrusion)
+    $print->remove_small_perimeters;
+    
+    # split fill_surfaces in internal and bridge surfaces
+    $print->split_bridges_fills;
+    
+    # detect which fill surfaces are near external layers
+    # they will be split in internal and internal-solid surfaces
     $print->discover_horizontal_shells;
     
+    # this will generate extrusion paths for each layer
     $print->extrude_fills;
     
-    
+    # output everything to a GCODE file
     if (!$self->output_file) {
         my $output_file = $self->input_file;
         $output_file =~ s/\.stl$/.gcode/i;
@@ -31,9 +55,12 @@ sub go {
     }
     $print->export_gcode($self->output_file);
     
+    # output some statistics
     my $processing_time = tv_interval($t0);
     printf "Done. Process took %d minutes and %.3f seconds\n", 
         int($processing_time/60), $processing_time - int($processing_time/60)*60;
+    
+    # TODO: more statistics!
 }
 
 1;

lib/Slic3r/Surface.pm

@@ -19,6 +19,29 @@ has 'surface_type' => (
     #isa     => enum([qw(internal internal-solid bottom top)]),
 );
 
+sub cast_from_polygon {
+    my $class = shift;
+    my ($polygon, %args) = @_;
+    
+    return $class->new(
+        contour      => Slic3r::Polyline::Closed->cast($polygon),
+        %args,
+    );
+}
+
+sub cast_from_expolygon {
+    my $class = shift;
+    my ($expolygon, %args) = @_;
+    
+    return $class->new(
+        contour      => Slic3r::Polyline::Closed->cast($expolygon->{outer}),
+        holes        => [
+            map Slic3r::Polyline::Closed->cast($_), @{$expolygon->{holes}}
+        ],
+        %args,
+    );
+}
+
 sub add_hole {
     my $self = shift;
     my ($hole) = @_;

lib/Slic3r/Surface/Bridge.pm

@@ -0,0 +1,8 @@
+package Slic3r::Surface::Bridge;
+use Moo;
+
+extends "Slic3r::Surface";
+
+has 'bridge_angle' => (is => 'ro');
+
+1;

t/geometry.t

@@ -2,7 +2,7 @@ use Test::More;
 use strict;
 use warnings;
 
-plan tests => 5;
+plan tests => 6;
 
 BEGIN {
     use FindBin;
@@ -49,6 +49,12 @@ is Slic3r::Geometry::point_in_segment($point, $line), 0, 'point_in_segment';
 
 #==========================================================
 
+$point = [ 736310778.185108, 5017423926.8924 ];
+my $line = [ [627484000, 3695776000], [750000000, 3720147000] ];
+is Slic3r::Geometry::point_in_segment($point, $line), 0, 'point_in_segment';
+
+#==========================================================
+
 my $polygons = [
     [ # contour, ccw
         [459190000, 5152739000], [147261000, 4612464000], [147261000, 3487535000], [339887000, 3153898000],