SuperSlicer/lib/Slic3r/Layer.pm

package Slic3r::Layer;
use Moo;

use Math::Clipper ':all';
use Slic3r::Geometry qw(collinear X Y A B PI);
use Slic3r::Geometry::Clipper qw(union_ex diff_ex intersection_ex PFT_EVENODD);
use XXX;

# a sequential number of layer, starting at 0
has 'id' => (
    is          => 'ro',
    #isa         => 'Int',
    required    => 1,
);

# collection of spare segments generated by slicing the original geometry;
# these need to be merged in continuos (closed) polylines
has 'lines' => (
    is      => 'rw',
    #isa     => 'ArrayRef[Slic3r::TriangleMesh::IntersectionLine]',
    default => sub { [] },
);

# collection of surfaces generated by slicing the original geometry
has '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::ExtrusionLoop]',
    default => sub { [] },
);

# ordered collection of extrusion paths to build skirt loops
has 'skirts' => (
    is      => 'rw',
    #isa     => 'ArrayRef[Slic3r::ExtrusionLoop]',
    default => sub { [] },
);

# collection of surfaces generated by offsetting the innermost perimeter(s)
# they represent boundaries of areas to fill
has 'fill_boundaries' => (
    is      => 'rw',
    #isa     => 'ArrayRef[Slic3r::Surface]',
    default => sub { [] },
);

# ordered collection of extrusion paths to fill surfaces
has 'fills' => (
    is      => 'rw',
    #isa     => 'ArrayRef[Slic3r::ExtrusionPath]',
    default => sub { [] },
);

# Z used for slicing
sub slice_z {
    my $self = shift;
    if ($self->id == 0) {
        return ($Slic3r::layer_height * $Slic3r::first_layer_height_ratio) / 2 / $Slic3r::resolution;
    }
    return (($Slic3r::layer_height * $Slic3r::first_layer_height_ratio)
        + (($self->id-1) * $Slic3r::layer_height)
        + ($Slic3r::layer_height/2)) / $Slic3r::resolution;
}

# Z used for printing
sub print_z {
    my $self = shift;
    return (($Slic3r::layer_height * $Slic3r::first_layer_height_ratio)
        + ($self->id * $Slic3r::layer_height)) / $Slic3r::resolution;
}

sub add_surface {
    my $self = shift;
    my (@vertices) = @_;
    
    # convert arrayref points to Point objects
    @vertices = map Slic3r::Point->new($_), @vertices;
    
    my $surface = Slic3r::Surface->new(
        contour => Slic3r::Polyline::Closed->new(points => \@vertices),
    );
    push @{ $self->surfaces }, $surface;
    
    # make sure our contour has its points in counter-clockwise order
    $surface->contour->make_counter_clockwise;
    
    return $surface;
}

sub add_line {
    my $self = shift;
    my ($line) = @_;
    
    push @{ $self->lines }, $line;
    return $line;
}

# build polylines from lines
sub make_surfaces {
    my $self = shift;
    my ($loops) = @_;
    
    {
        my $expolygons = union_ex($loops, PFT_EVENODD);
        Slic3r::debugf "  %d surface(s) having %d holes detected from %d polylines\n",
            scalar(@$expolygons), scalar(map $_->holes, @$expolygons), scalar(@$loops);
        
        push @{$self->surfaces},
            map Slic3r::Surface->cast_from_expolygon($_, surface_type => 'internal'),
                @$expolygons;
    }
    
    #use Slic3r::SVG;
    #Slic3r::SVG::output(undef, "surfaces.svg",
    #    polygons        => [ map $_->contour->p, @{$self->surfaces} ],
    #    red_polygons    => [ map $_->p, map @{$_->holes}, @{$self->surfaces} ],
    #);
}

sub remove_small_surfaces {
    my $self = shift;
    my @good_surfaces = ();
    
    my $distance = ($Slic3r::flow_width / 2 / $Slic3r::resolution);
    
    my @surfaces = @{$self->surfaces};
    @{$self->surfaces} = ();
    foreach my $surface (@surfaces) {
        # offset inwards
        my @offsets = $surface->expolygon->offset_ex(-$distance);
        
        # offset the results outwards again and merge the results
        @offsets = map $_->offset_ex($distance), @offsets;
        @offsets = @{ union_ex([ map @$_, @offsets ]) };
        
        # the difference between $surface->expolygon and @offsets 
        # is what we can't print since it's too small
        
        push @{$self->surfaces}, map Slic3r::Surface->cast_from_expolygon($_,
            surface_type => $surface->surface_type), @offsets;
    }
    
    Slic3r::debugf "removed %d small surfaces at layer %d\n",
        (@surfaces - @{$self->surfaces}), $self->id 
        if @{$self->surfaces} != @surfaces;
}

sub remove_small_perimeters {
    my $self = shift;
    my @good_perimeters = grep $_->is_printable, @{$self->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;
}

# make bridges printable
sub process_bridges {
    my $self = shift;
    
    # no bridges are possible if we have no internal surfaces
    return if $Slic3r::fill_density == 0;
    
    my @bridges = ();
    
    # a bottom surface on a layer > 0 is either a bridge or a overhang 
    # or a combination of both; any top surface is a candidate for
    # reverse bridge processing
    
    my @solid_surfaces = grep {
        ($_->surface_type eq 'bottom' && $self->id > 0) || $_->surface_type eq 'top'
    } @{$self->surfaces} or return;
    
    my @internal_surfaces = grep $_->surface_type =~ /internal/, @{$self->surfaces};
    
    SURFACE: foreach my $surface (@solid_surfaces) {
        my $expolygon = $surface->expolygon->safety_offset;
        my $description = $surface->surface_type eq 'bottom' ? 'bridge/overhang' : 'reverse bridge';
        
        # offset the contour and intersect it with the internal surfaces to discover 
        # which of them has contact with our bridge
        my @supporting_surfaces = ();
        my ($contour_offset) = $expolygon->contour->offset($Slic3r::flow_width / $Slic3r::resolution);
        foreach my $internal_surface (@internal_surfaces) {
            my $intersection = intersection_ex([$contour_offset], [$internal_surface->contour->p]);
            if (@$intersection) {
                push @supporting_surfaces, $internal_surface;
            }
        }
        
            #use Slic3r::SVG;
            #Slic3r::SVG::output(undef, "bridge.svg",
            #    green_polygons  => [ map $_->p, @supporting_surfaces ],
            #    red_polygons    => [ @$expolygon ],
            #);
        
        next SURFACE unless @supporting_surfaces;
        Slic3r::debugf "  Found $description on layer %d with %d support(s)\n", 
            $self->id, scalar(@supporting_surfaces);
        
        my $bridge_angle = undef;
        if ($surface->surface_type eq 'bottom') {
            # detect optimal bridge angle
            
            my $bridge_over_hole = 0;
            my @edges = ();  # edges are POLYLINES
            foreach my $supporting_surface (@supporting_surfaces) {
                my @surface_edges = $supporting_surface->contour->clip_with_polygon($contour_offset);
                if (@surface_edges == 1 && @{$supporting_surface->contour->p} == @{$surface_edges[0]->p}) {
                    $bridge_over_hole = 1;
                } else {
                    foreach my $edge (@surface_edges) {
                        shift @{$edge->points};
                        pop @{$edge->points};
                    }
                    @surface_edges = grep { @{$_->points} } @surface_edges;
                }
                push @edges, @surface_edges;
            }
            Slic3r::debugf "    Bridge is supported on %d edge(s)\n", scalar(@edges);
            Slic3r::debugf "    and covers a hole\n" if $bridge_over_hole;
            
            if (0) {
                require "Slic3r/SVG.pm";
                Slic3r::SVG::output(undef, "bridge.svg",
                    polylines       => [ map $_->p, @edges ],
                );
            }
            
            if (@edges == 2) {
                my @chords = map Slic3r::Line->new($_->points->[0], $_->points->[-1]), @edges;
                my @midpoints = map $_->midpoint, @chords;
                $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;
            }
        }
        
        # now, extend our bridge by taking a portion of supporting surfaces
        {
            # offset the bridge by the specified amount of mm (minimum 3)
            my $bridge_overlap = 3 / $Slic3r::resolution;
            my ($bridge_offset) = $expolygon->contour->offset($bridge_overlap, $Slic3r::resolution * 100, JT_MITER, 2);
            
            # calculate the new bridge
            my $intersection = intersection_ex(
                [ @$expolygon, map $_->p, @supporting_surfaces ],
                [ $bridge_offset ],
            );
            
            push @bridges, map Slic3r::Surface->cast_from_expolygon($_,
                surface_type => $surface->surface_type,
                bridge_angle => $bridge_angle,
            ), @$intersection;
        }
    }
    
    # now we need to merge bridges to avoid overlapping
    {
        # build a list of unique bridge types
        my @surface_groups = Slic3r::Surface->group(@bridges);
        
        # merge bridges of the same type, removing any of the bridges already merged;
        # the order of @surface_groups determines the priority between bridges having 
        # different surface_type or bridge_angle
        @bridges = ();
        foreach my $surfaces (@surface_groups) {
            my $union = union_ex([ map $_->p, @$surfaces ]);
            my $diff = diff_ex(
                [ map @$_, @$union ],
                [ map $_->p, @bridges ],
            );
            
            push @bridges, map Slic3r::Surface->cast_from_expolygon($_,
                surface_type => $surfaces->[0]->surface_type,
                bridge_angle => $surfaces->[0]->bridge_angle,
            ), @$union;
        }
    }
    
    # apply bridges to layer
    {
        my @surfaces = @{$self->surfaces};
        @{$self->surfaces} = ();
        
        # intersect layer surfaces with bridges to get actual bridges
        foreach my $bridge (@bridges) {
            my $actual_bridge = intersection_ex(
                [ map $_->p, @surfaces ],
                [ $bridge->p ],
            );
            
            push @{$self->surfaces}, map Slic3r::Surface->cast_from_expolygon($_,
                surface_type => $bridge->surface_type,
                bridge_angle => $bridge->bridge_angle,
            ), @$actual_bridge;
        }
        
        # difference between layer surfaces and bridges are the other surfaces
        foreach my $group (Slic3r::Surface->group(@surfaces)) {
            my $difference = diff_ex(
                [ map $_->p, @$group ],
                [ map $_->p, @bridges ],
            );
            push @{$self->surfaces}, map Slic3r::Surface->cast_from_expolygon($_,
                surface_type => $group->[0]->surface_type), @$difference;
        }
    }
}

1;