Completely rewritten the slicing algorithm

It should work with any model now. There are still problems with some
bridges.

lib/Slic3r/Geometry.pm

@@ -17,7 +17,7 @@ our @EXPORT_OK = qw(
     clip_segment_complex_polygon longest_segment angle3points
 );
 
-use Slic3r::Geometry::DouglasPeucker ();
+use Slic3r::Geometry::DouglasPeucker qw(Douglas_Peucker);
 use XXX;
 
 use constant PI => 4 * atan2(1, 1);

lib/Slic3r/Layer.pm

@@ -121,10 +121,17 @@ sub remove_surface {
     @{ $self->surfaces } = grep $_ ne $surface, @{ $self->surfaces };
 }
 
-# build polylines of lines which do not already belong to a surface
-sub make_polylines {
+# build polylines from lines
+sub make_surfaces {
     my $self = shift;
     
+    # this algorithm can be further simplified:
+    # first remove all facetedges that are not connected to any other edge
+    # or that are connected to more than one edge: those are the edges
+    # tangent to our plane, that we don't care about;
+    # then we would have all points connecting two and only two lines,
+    # so a simple head-to-tail algorithm would work
+    
     my @lines = ();
     push @lines, map $_->p, @{$self->lines};
     
@@ -134,7 +141,7 @@ sub make_polylines {
     #    red_lines   => [ map $_->p, grep  $_->isa('Slic3r::Line::FacetEdge'), @{$self->lines} ],
     #);
     
-    my $get_point_id = sub { sprintf "%d,%d", @{$_[0]} };
+    my $get_point_id = sub { sprintf "%.0f,%.0f", @{$_[0]} };
     
     my (%pointmap) = ();
     foreach my $line (@lines) {
@@ -193,166 +200,16 @@ sub make_polylines {
     #    polylines => [ @polylines ],
     #);
     
-    return [ map Slic3r::Polyline::Closed->cast($_), @polylines ];
-}
-
-sub make_surfaces {
-    my $self = shift;
-    my ($polylines) = @_;
-    
-    #use Slic3r::SVG;
-    #Slic3r::SVG::output_polygons($main::print, "polylines.svg", [ map $_->p, @$polylines ]);
-    
-    # count how many other polylines enclose each polyline
-    # even = contour; odd = hole
-    my %enclosing_polylines = ();
-    my %enclosing_polylines_count = ();
-    my $max_depth = 0;
-    foreach my $polyline (@$polylines) {
-        # a polyline encloses another one if any point of it is enclosed
-        # in the other
-        my $point = $polyline->points->[0];
-        my $ordered_id = $polyline->id;
-        
-        # find polylines contaning $point, and thus $polyline
-        $enclosing_polylines{$polyline} = 
-            [ grep $_->id ne $ordered_id && $_->encloses_point($point), @$polylines ];
-        $enclosing_polylines_count{$polyline} = scalar @{ $enclosing_polylines{$polyline} };
-        
-        $max_depth = $enclosing_polylines_count{$polyline}
-            if $enclosing_polylines_count{$polyline} > $max_depth;
-    }
-    
-    # make a cache for contours and surfaces
-    my %surfaces = ();   # contour => surface
-    
-    # start looking at most inner polylines
-    for (; $max_depth > -1; $max_depth--) {
-        foreach my $polyline (@$polylines) {
-            next unless $enclosing_polylines_count{$polyline} == $max_depth;
-            
-            my $surface;
-            if ($enclosing_polylines_count{$polyline} % 2 == 0) {
-                # this is a contour
-                $polyline->make_counter_clockwise;
-                $surface = Slic3r::Surface->new(contour => $polyline);
-            } else {
-                # this is a hole
-                $polyline->make_clockwise;
-                
-                # find the enclosing polyline having immediately close depth
-                my ($contour) = grep $enclosing_polylines_count{$_} == ($max_depth-1), 
-                    @{ $enclosing_polylines{$polyline} };
-                
-                if ($surfaces{$contour}) {
-                    $surface = $surfaces{$contour};
-                    $surface->add_hole($polyline);
-                } else {
-                    $surface = Slic3r::Surface->new(
-                        contour => $contour,
-                        holes   => [$polyline],
-                    );
-                    $surfaces{$contour} = $surface;
-                }
-            }
-            
-            # check whether we already have this surface
-            next if grep $_->id eq $surface->id, @{ $self->surfaces };
-            
-            $surface->surface_type('internal');
-            push @{ $self->surfaces }, $surface;
-            
-            Slic3r::debugf "New surface: %s (%d holes: %s)\n", 
-                $surface->id, scalar @{$surface->holes},
-                join(', ', map $_->id, @{$surface->holes}) || 'none'
-                if $Slic3r::debug;
-        }
-    }
-}
-
-sub merge_contiguous_surfaces {
-    my $self = shift;
-    
-    if ($Slic3r::debug) {
-        Slic3r::debugf "Initial surfaces (%d):\n", scalar @{ $self->surfaces };
-        Slic3r::debugf "  [%s] %s (%s with %d holes)\n", $_->surface_type, $_->id, 
-            ($_->contour->is_counter_clockwise ? 'ccw' : 'cw'), scalar @{$_->holes} for @{ $self->surfaces };
-        #Slic3r::SVG::output_polygons(undef, "polygons-before.svg", [ map $_->contour->p, @{$self->surfaces} ]);
-    }
-    
-    my %resulting_surfaces = ();
+    #@polylines = map Slic3r::Polyline::Closed->cast($_), @polylines;
     
-    # only merge surfaces with same type
-    foreach my $type (qw(bottom top internal)) {
+    {
         my $clipper = Math::Clipper->new;
-        my @surfaces = grep $_->surface_type eq $type, @{$self->surfaces}
-            or next;
-        
-        #Slic3r::SVG::output_polygons($main::print, "polygons-$type-before.svg", [ map $_->contour->p, @surfaces ]);
-        $clipper->add_subject_polygons([ map $_->contour->p, @surfaces ]);
-        
-        my $result = $clipper->ex_execute(CT_UNION, PFT_NONZERO, PFT_NONZERO);
-        $clipper->clear;
-        
-        my @extra_holes = map @{$_->{holes}}, @$result;
-        $result = [ map $_->{outer}, @$result ];
-        #Slic3r::SVG::output_polygons($main::print, "polygons-$type-union.svg", $result);
-        
-        # subtract bottom or top surfaces from internal
-        if ($type eq 'internal') {
-            $clipper->add_subject_polygons($result);
-            $clipper->add_clip_polygons([ map $_->{outer}, @{$resulting_surfaces{$_}} ])
-                for qw(bottom top);
-            $result = $clipper->execute(CT_DIFFERENCE, PFT_NONZERO, PFT_NONZERO);
-            $clipper->clear;
-        }
-        
-        # apply holes
-        $clipper->add_subject_polygons($result);
-        $result = $clipper->execute(CT_DIFFERENCE, PFT_NONZERO, PFT_NONZERO);
-        $clipper->clear;
+        $clipper->add_subject_polygons([ @polylines ]);
+        my $expolygons = $clipper->ex_execute(CT_UNION, PFT_NONZERO, PFT_NONZERO);
         
-        $clipper->add_subject_polygons($result);
-        $clipper->add_clip_polygons([ @extra_holes ]) if @extra_holes;
-        $clipper->add_clip_polygons([ map $_->p, map @{$_->holes}, @surfaces ]);
-        my $result2 = $clipper->ex_execute(CT_DIFFERENCE, PFT_NONZERO, PFT_NONZERO);
-        
-        $resulting_surfaces{$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) {
-        foreach my $p (@{ $resulting_surfaces{$type} }) {
-            push @{ $self->surfaces }, Slic3r::Surface->new(
-                surface_type => $type,
-                contour => Slic3r::Polyline::Closed->cast($p->{outer}),
-                holes   => [
-                    map Slic3r::Polyline::Closed->cast($_), @{$p->{holes}}
-                ],
-            );
-        }
-    }
-    
-    if ($Slic3r::debug) {
-        Slic3r::debugf "Final surfaces (%d):\n", scalar @{ $self->surfaces };
-        Slic3r::debugf "  [%s] %s (%s with %d holes)\n", $_->surface_type, $_->id, 
-            ($_->contour->is_counter_clockwise ? 'ccw' : 'cw'), scalar @{$_->holes} for @{ $self->surfaces };
+        Slic3r::debugf "  %d surface(s) detected from %d polylines\n",
+            scalar(@$expolygons), scalar(@polylines);
+        push @{$self->surfaces}, map Slic3r::Surface->cast_from_expolygon($_, surface_type => 'internal'), @$expolygons;
     }
 }
 
@@ -360,6 +217,7 @@ sub remove_small_surfaces {
     my $self = shift;
     my @good_surfaces = ();
     
+    my $surface_count = scalar @{$self->surfaces};
     foreach my $surface (@{$self->surfaces}) {
         next if !$surface->contour->is_printable;
         @{$surface->holes} = grep $_->is_printable, @{$surface->holes};
@@ -367,12 +225,16 @@ sub remove_small_surfaces {
     }
     
     @{$self->surfaces} = @good_surfaces;
+    Slic3r::debugf "removed %d small surfaces at layer %d\n",
+        ($surface_count - @good_surfaces), $self->id 
+        if @good_surfaces != $surface_count;
 }
 
 sub remove_small_perimeters {
     my $self = shift;
     my @good_perimeters = grep $_->is_printable, @{$self->perimeters};
-    Slic3r::debugf "removed %d unprintable perimeters\n", (@{$self->perimeters} - @good_perimeters) 
+    Slic3r::debugf "removed %d unprintable perimeters at layer %d\n",
+        (@{$self->perimeters} - @good_perimeters), $self->id
         if @good_perimeters != @{$self->perimeters};
     
     @{$self->perimeters} = @good_perimeters;
@@ -400,9 +262,9 @@ sub process_bridges {
         {
             my @current_polyline = ();
             EDGE: foreach my $edge (Slic3r::Geometry::polygon_lines($surface_p)) {
-                for (@supporting_surfaces) {
+                for my $supporting_surface (@supporting_surfaces) {
                     local $Slic3r::Geometry::epsilon = 1E+7;
-                    if (Slic3r::Geometry::polygon_has_subsegment($_->contour->p, $edge)) {
+                    if (Slic3r::Geometry::polygon_has_subsegment($supporting_surface->contour->p, $edge)) {
                         push @current_polyline, $edge;
                         next EDGE;
                     }

lib/Slic3r/Point.pm

@@ -4,13 +4,13 @@ use Moo;
 has 'x' => (
     is          => 'ro',
     required    => 1,
-    coerce      => sub { sprintf '%.0f', $_[0] },
+    #coerce      => sub { sprintf '%.0f', $_[0] },
 );
 
 has 'y' => (
     is          => 'ro',
     required    => 1,
-    coerce      => sub { sprintf '%.0f', $_[0] },
+    #coerce      => sub { sprintf '%.0f', $_[0] },
 );
 
 sub cast {

lib/Slic3r/Polyline.pm

@@ -3,6 +3,7 @@ use Moo;
 
 use Math::Clipper qw();
 use Sub::Quote;
+use XXX;
 
 # arrayref of ordered points
 has 'points' => (
@@ -61,9 +62,14 @@ sub merge_continuous_lines {
 
 sub cleanup {
     my $self = shift;
-    my $tolerance = shift || (1 / $Slic3r::resolution);
-    @{$self->points} = map Slic3r::Point->cast($_), 
+    my $tolerance = shift || 10;
+    
+    my $points = $self->p;
+    push @$points, $points->[0] if $self->isa('Slic3r::Polyline::Closed');
+    my @clean_points = map Slic3r::Point->cast($_), 
         Slic3r::Geometry::Douglas_Peucker($self->p, $tolerance);
+    pop @clean_points if $self->isa('Slic3r::Polyline::Closed');
+    @{$self->points} = @clean_points;
 }
 
 sub reverse_points {

lib/Slic3r/Print.pm

@@ -34,16 +34,17 @@ sub new_from_stl {
     
     print "\n==> PROCESSING SLICES:\n";
     foreach my $layer (@{ $print->layers }) {
-        printf "\nProcessing layer %d:\n", $layer->id;
+        printf "Making surfaces for layer %d:\n", $layer->id;
         
-        # build polylines of lines which do not already belong to a surface
-        my $polylines = $layer->make_polylines;
+        # layer currently has many lines representing intersections of
+        # model facets with the layer plane. there may also be lines
+        # that we need to ignore (for example, when two non-horizontal
+        # facets share a common edge on our plane, we get a single line;
+        # however that line has no meaning for our layer as it's enclosed
+        # inside a closed polyline)
         
-        # build surfaces of polylines (distinguishing contours from holes)
-        $layer->make_surfaces($polylines);
-        
-        # merge surfaces having a common line
-        $layer->merge_contiguous_surfaces;
+        # build surfaces from sparse lines
+        $layer->make_surfaces;
     }
     
     return $print;
@@ -74,6 +75,82 @@ sub layer {
     return $self->layers->[$layer_id];
 }
 
+sub detect_surfaces_type {
+    my $self = shift;
+    
+    my $clipper = Math::Clipper->new;
+    
+    # prepare a reusable subroutine to make surface differences
+    my $surface_difference = sub {
+        my ($subject_surfaces, $clip_surfaces, $result_type) = @_;
+        $clipper->clear;
+        $clipper->add_subject_polygons([ map $_->p, @$subject_surfaces ]);
+        $clipper->add_clip_polygons([ map { ref $_ eq 'ARRAY' ? $_ : $_->p } @$clip_surfaces ]);
+        my $expolygons = $clipper->ex_execute(CT_DIFFERENCE, PFT_NONZERO, PFT_NONZERO);
+        return grep $_->contour->is_printable,
+            map Slic3r::Surface->cast_from_expolygon($_, surface_type => $result_type), 
+            @$expolygons;
+    };
+    
+    for (my $i = 0; $i < $self->layer_count; $i++) {
+        my $layer = $self->layers->[$i];
+        my $upper_layer = $self->layers->[$i+1];
+        my $lower_layer = $i > 0 ? $self->layers->[$i-1] : undef;
+        
+        my (@bottom, @top, @internal) = ();
+        
+        # find top surfaces (difference between current surfaces
+        # of current layer and upper one)
+        if ($upper_layer) {
+            # offset upper layer surfaces by extrusion_width * perimeters
+            my $upper_surfaces = offset(
+                [ map $_->p, @{$upper_layer->surfaces} ],
+                ($Slic3r::flow_width / $Slic3r::resolution * $Slic3r::perimeter_offsets),
+                $Slic3r::resolution * 100,
+                JT_MITER, 2,
+            );
+            @top = $surface_difference->($layer->surfaces, $upper_surfaces, 'top');
+        } else {
+            # if no upper layer, all surfaces of this one are solid
+            @top = @{$layer->surfaces};
+            $_->surface_type('top') for @top;
+        }
+        
+        # find bottom surfaces (difference between current surfaces
+        # of current layer and lower one)
+        if ($lower_layer) {
+            @bottom = $surface_difference->($layer->surfaces, $lower_layer->surfaces, 'bottom');
+            
+            #Slic3r::SVG::output(undef, "layer_" . $layer->id . "_diff.svg",
+            #    green_polygons  => [ map $_->p, @{$layer->surfaces} ],
+            #    red_polygons    => [ map $_->p, @{$lower_layer->surfaces} ],
+            #);
+            
+            
+        } else {
+            # if no lower layer, all surfaces of this one are solid
+            @bottom = @{$layer->surfaces};
+            $_->surface_type('bottom') for @bottom;
+        }
+        
+        # find internal surfaces (difference between top/bottom surfaces and others)
+        @internal = $surface_difference->($layer->surfaces, [@top, @bottom], 'internal');
+        
+        # save surfaces to layer
+        $layer->surfaces([ @bottom, @top, @internal ]);
+        
+        #use Slic3r::SVG;
+        #Slic3r::SVG::output(undef, "layer_" . $layer->id . ".svg",
+        #    white_polygons  => [ map $_->p, @internal ],
+        #    green_polygons  => [ map $_->p, @bottom ],
+        #    red_polygons    => [ map $_->p, @top ],
+        #);
+        
+        Slic3r::debugf "  layer %d has %d bottom, %d top and %d internal surfaces\n",
+            $layer->id, scalar(@bottom), scalar(@top), scalar(@internal);
+    }
+}
+
 sub discover_horizontal_shells {
     my $self = shift;
     
@@ -97,7 +174,7 @@ sub discover_horizontal_shells {
                 Slic3r::debugf "  looking for neighbors on layer %d...\n", $n;
                 
                 foreach my $surf_coll (@{$self->layers->[$n]->fill_surfaces}) {
-                    my $neighbor_polygons = [ map $_->p, grep $_->surface_type eq 'internal', @{$surf_coll->surfaces} ];
+                    my $neighbor_polygons = [ map $_->p, grep $_->surface_type =~ /internal/, @{$surf_coll->surfaces} ];
                     
                     # find intersection between @surfaces and current layer's surfaces
                     $clipper->add_subject_polygons([ map $_->p, @surfaces ]);

lib/Slic3r/STL.pm

@@ -80,11 +80,6 @@ sub parse_file {
         foreach my $vertex (@vertices) {
             $vertex->[$_] = ($Slic3r::scale * $vertex->[$_] / $Slic3r::resolution) + $shift[$_]
                 for X,Y,Z;
-            
-            # round Z coordinates to the nearest multiple of layer height
-            # XY will be rounded automatically to integers with coercion
-            $vertex->[Z] = int($vertex->[Z] * $Slic3r::resolution / $Slic3r::layer_height)
-                * $Slic3r::layer_height / $Slic3r::resolution;
         }
         
         foreach my $copy (@copies) {
@@ -113,10 +108,14 @@ sub _facet {
     }
     Slic3r::debugf "z: min = %.0f, max = %.0f\n", $min_z, $max_z;
     
+    if ($min_z == $max_z) {
+        Slic3r::debugf "Facet is horizontal; ignoring\n";
+        return;
+    }
+    
     # calculate the layer extents
     my $min_layer = int($min_z * $Slic3r::resolution / $Slic3r::layer_height);
-    my $max_layer = int(0.99999 + ($max_z * $Slic3r::resolution / $Slic3r::layer_height));
-    
+    my $max_layer = int($max_z * $Slic3r::resolution / $Slic3r::layer_height);
     Slic3r::debugf "layers: min = %s, max = %s\n", $min_layer, $max_layer;
     
     # reorder vertices so that the first one is the one with lowest Z
@@ -127,62 +126,6 @@ sub _facet {
         @vertices = (splice(@vertices, $z_order[0]), splice(@vertices, 0, $z_order[0]));
     }
     
-    # is the facet horizontal?
-    # (note that we can have $min_z == $max_z && $min_layer != $max_layer
-    # if $min_z % $layer_height != 0)
-    if ($min_z == $max_z) {
-        my $layer = $print->layer($min_layer);
-        
-        # if all vertices are aligned, then facet is not horizontal but vertical
-        # with a height less than layer height: that's why it was squashed on a
-        # single layer
-        ##local $Slic3r::Geometry::parallel_degrees_limit = 1;
-        ##if (three_points_aligned(@vertices)) {
-        if (0 && abs($normal->[Z]) == 0) {
-            Slic3r::debugf "Facet is vertical with a height less than layer height\n";
-            
-            my ($p1, $p2, $p3) = @vertices;
-            $layer->add_line(Slic3r::Line::FacetEdge->cast(
-                $_,
-                edge_type => 'bottom',
-            )) for ([$p1, $p2], [$p2, $p3], [$p1, $p3], [$p2, $p1], [$p3, $p2], [$p3, $p1]);
-            
-            return;
-        }
-        
-        Slic3r::debugf "Facet is horizontal\n";
-        my $surface = $layer->add_surface(@vertices);
-        
-        # to determine whether the surface is a top or bottom let's recompute
-        # the normal using the right-hand rule
-        # (this relies on the STL to be well-formed)
-        # recompute the normal using the right-hand rule
-        my $vertices_p = [@vertices];
-        integerize_coordinate_sets($vertices_p);
-        my $clockwise = !is_counter_clockwise($vertices_p);
-        
-        # defensive programming and/or input check
-        if (abs($normal->[Z]) == 1) {
-            # while the vertices may belong to the same layer, it doesn't mean the facet
-            # was horizontal in the original model; so this check makes sense only 
-            # if the original normal is exactly 1 or -1
-            if (($normal->[Z] > 0 && $clockwise) || ($normal->[Z] < 0 && !$clockwise)) {
-                YYY $normal;
-                die sprintf "STL normal (%.0f) and right-hand rule computation (%s) differ!\n",
-                    $normal->[Z], $clockwise ? 'clockwise' : 'counter-clockwise';
-            }
-        }
-        
-        if ($layer->id == 0 && !$clockwise) {
-            YYY $normal;
-            die "Right-hand rule gives bad result for facets on base layer!\n";
-        }
-        
-        $surface->surface_type($clockwise ? 'bottom' : 'top');
-        
-        return;
-    }
-    
     for (my $layer_id = $min_layer; $layer_id <= $max_layer; $layer_id++) {
         my $layer = $print->layer($layer_id);
         $layer->add_line($_) for $self->intersect_facet(\@vertices, $layer->z);

lib/Slic3r/SVG.pm

@@ -39,14 +39,15 @@ sub output {
     
     my $svg = svg($print);
     
-    foreach my $type (qw(polygons polylines white_polygons red_polygons red_polylines)) {
+    foreach my $type (qw(polygons polylines white_polygons green_polygons red_polygons red_polylines)) {
         if ($things{$type}) {
             my $method = $type =~ /polygons/ ? 'polygon' : 'polyline';
+            my ($colour) = $type =~ /^(red|green)_/;
             my $g = $svg->group(
                 style => {
                     'stroke-width' => 2,
-                    'stroke' => $type =~ /red_/ ? 'red' : 'black',
-                    'fill' => ($type !~ /polygons/ ? 'none' : ($type =~ /red_/ ? 'red' : 'grey')),
+                    'stroke' => $colour || 'black',
+                    'fill' => ($type !~ /polygons/ ? 'none' : ($colour || 'grey')),
                 },
             );
             foreach my $polygon (@{$things{$type}}) {
@@ -57,7 +58,6 @@ sub output {
                 );
                 $g->$method(
                     %$path,
-                    'marker-end' => "url(#endArrow)",
                 );
             }
         }

lib/Slic3r/Skein.pm

@@ -16,10 +16,13 @@ sub go {
     my $t0 = [gettimeofday];
     
     # skein the STL into layers
-    # each layer has surfaces with holes; surfaces are distinguished
-    # in top/bottom/internal
+    # each layer has surfaces with holes
     my $print = Slic3r::Print->new_from_stl($self->input_file);
     
+    # this will detect the type of each surface (top/bottom/internal)
+    # by splitting them if necessary
+    $print->detect_surfaces_type;
+    
     # this will remove unprintable surfaces
     # (those that are too tight for extrusion)
     $print->remove_small_surfaces;