From 415d1a51700ff2982d08515e48bfce09d79ae75a Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Mon, 26 Sep 2011 10:52:58 +0200
Subject: [PATCH] Optimization of travel paths for fills

---
 README.markdown                        |   1 -
 lib/Slic3r.pm                          |   4 +-
 lib/Slic3r/ExtrusionPath.pm            |  12 ++
 lib/Slic3r/ExtrusionPath/Collection.pm |  55 ++++++
 lib/Slic3r/Fill/Rectilinear.pm         | 257 +++++++++++++------------
 lib/Slic3r/Geometry.pm                 |   1 +
 lib/Slic3r/Perimeter.pm                |  19 +-
 lib/Slic3r/Print.pm                    |   7 +-
 lib/Slic3r/Surface/Collection.pm       |  10 +
 9 files changed, 230 insertions(+), 136 deletions(-)
 create mode 100644 lib/Slic3r/ExtrusionPath/Collection.pm
 create mode 100644 lib/Slic3r/Surface/Collection.pm

diff --git a/README.markdown b/README.markdown
index ad65a7561..3058fb8bf 100644
--- a/README.markdown
+++ b/README.markdown
@@ -42,7 +42,6 @@ Roadmap includes the following goals:
 * output some statistics;
 * allow the user to customize initial and final GCODE commands;
 * support material for internal perimeters;
-* travel path optimization;
 * ability to infill in the direction of bridges;
 * input object transform (scale, rotate, multiply);
 * cool;
diff --git a/lib/Slic3r.pm b/lib/Slic3r.pm
index d9db1381b..f6fff16d1 100644
--- a/lib/Slic3r.pm
+++ b/lib/Slic3r.pm
@@ -10,6 +10,7 @@ sub debugf {
 
 use Slic3r::ExtrusionLoop;
 use Slic3r::ExtrusionPath;
+use Slic3r::ExtrusionPath::Collection;
 use Slic3r::Fill;
 use Slic3r::Geometry;
 use Slic3r::Layer;
@@ -21,6 +22,7 @@ use Slic3r::Polyline::Closed;
 use Slic3r::Print;
 use Slic3r::STL;
 use Slic3r::Surface;
+use Slic3r::Surface::Collection;
 
 # printer options
 our $nozzle_diameter    = 0.45;
@@ -33,7 +35,7 @@ our $filament_packing_density = 0.85;
 
 # speed options
 our $print_feed_rate            = 60;   # mm/sec
-our $travel_feed_rate           = 80;   # mm/sec
+our $travel_feed_rate           = 130;   # mm/sec
 our $bottom_layer_speed_ratio   = 0.6;
 
 # accuracy options
diff --git a/lib/Slic3r/ExtrusionPath.pm b/lib/Slic3r/ExtrusionPath.pm
index 8df519789..580ed3bd5 100644
--- a/lib/Slic3r/ExtrusionPath.pm
+++ b/lib/Slic3r/ExtrusionPath.pm
@@ -22,4 +22,16 @@ sub clip_end {
     }
 }
 
+sub endpoints {
+    my $self = shift;
+    my ($as_arrayref) = @_;
+    my @points = ($self->points->[0], $self->points->[-1]);
+    return $as_arrayref ? map($_->p, @points) : @points;
+}
+
+sub reverse {
+    my $self = shift;
+    @{$self->points} = reverse @{$self->points};
+}
+
 1;
diff --git a/lib/Slic3r/ExtrusionPath/Collection.pm b/lib/Slic3r/ExtrusionPath/Collection.pm
new file mode 100644
index 000000000..dda6e1d37
--- /dev/null
+++ b/lib/Slic3r/ExtrusionPath/Collection.pm
@@ -0,0 +1,55 @@
+package Slic3r::ExtrusionPath::Collection;
+use Moo;
+
+use XXX;
+
+has 'paths' => (
+    is      => 'rw',
+    #isa     => 'ArrayRef[Slic3r::ExtrusionPath]',
+    default => sub { [] },
+);
+
+sub add {
+    my $self = shift;
+    my ($path) = @_;
+    
+    push @{$self->paths}, $path;
+}
+
+sub endpoints {
+    my $self = shift;
+    my ($as_arrayref) = @_;
+    return map $_->endpoints($as_arrayref), @{$self->paths};
+}
+
+sub shortest_path {
+    my $self = shift;
+    my ($start_near) = @_;
+    
+    # get point as arrayref
+    $start_near = $start_near->p if $start_near && ref $start_near ne 'ARRAY';
+    
+    my @paths = ();
+    my $start_at;
+    CYCLE: while (@{$self->paths}) {
+        # find nearest point
+        $start_at = Slic3r::Point->cast(Slic3r::Geometry::nearest_point($start_near, [ $self->endpoints(1) ]));
+        
+        # loop through paths to find the one that starts or ends at the point found
+        PATH: for (my $i = 0; $i <= $#{$self->paths}; $i++) {
+            if ($start_at->id eq $self->paths->[$i]->points->[0]->id) {
+                push @paths, splice @{$self->paths}, $i, 1;
+            } elsif ($start_at->id eq $self->paths->[$i]->points->[-1]->id) {
+                $self->paths->[$i]->reverse;
+                push @paths, splice @{$self->paths}, $i, 1;
+            } else {
+                next PATH;
+            }
+            $start_near = $paths[-1]->points->[-1]->p;
+            next CYCLE;
+        }
+    }
+    return @paths;
+}
+
+1;
diff --git a/lib/Slic3r/Fill/Rectilinear.pm b/lib/Slic3r/Fill/Rectilinear.pm
index 65013ec1e..ef419a0f8 100644
--- a/lib/Slic3r/Fill/Rectilinear.pm
+++ b/lib/Slic3r/Fill/Rectilinear.pm
@@ -21,145 +21,154 @@ sub make_fill {
     printf "Filling layer %d:\n", $layer->id;
     
     my $max_print_dimension = $print->max_length;
+    
     my $n = 1;
-    SURFACE: foreach my $surface (@{ $layer->fill_surfaces }) {
-        Slic3r::debugf " Processing surface %s:\n", $surface->id;
-        my $polygon = $surface->mgp_polygon;
+    foreach my $surface_collection (@{ $layer->fill_surfaces }) {
+        my @path_collection = ();
         
-        # alternate fill direction
-        my (@rotate, @shift);
-        if ($layer->id % 2) {
-            @rotate = ( PI/2, [ $print->x_length / 2, $print->y_length / 2 ] );
-            $shift[X] = $print->y_length / 2 - $print->x_length / 2;
-            $shift[Y] = -$shift[X];
-        }
-        
-        # TODO: here we should implement an "infill in direction of bridges" option
-        
-        # rotate surface as needed
-        $polygon = $polygon->rotate(@rotate)->move(@shift) if @rotate;
-        
-        # force 100% density for external surfaces
-        my $density = $surface->surface_type eq 'internal' ? $Slic3r::fill_density : 1;
-        next SURFACE unless $density > 0;
-        
-        my $distance_between_lines = $Slic3r::flow_width / $Slic3r::resolution / $density;
-        my $number_of_lines = ceil($max_print_dimension / $distance_between_lines);
-
-        printf "distance = %f\n", $distance_between_lines;
-        printf "number_of_lines = %d\n", $number_of_lines;
-        
-        # this arrayref will hold intersection points of the fill grid with surface segments
-        my $points = [ map [], 0..$number_of_lines-1 ];
-        foreach my $line (map $self->_lines_from_mgp_points($_), @{ $polygon->polygons }) {
+        SURFACE: foreach my $surface (@{ $surface_collection->surfaces }) {
+            Slic3r::debugf " Processing surface %s:\n", $surface->id;
+            my $polygon = $surface->mgp_polygon;
             
-            # find out the coordinates
-            my @coordinates = map @$_, @$line;
+            # alternate fill direction
+            my (@rotate, @shift);
+            if ($layer->id % 2) {
+                @rotate = ( PI/2, [ $print->x_length / 2, $print->y_length / 2 ] );
+                $shift[X] = $print->y_length / 2 - $print->x_length / 2;
+                $shift[Y] = -$shift[X];
+            }
             
-            # get the extents of the segment along the primary axis
-            my @line_c = sort { $a <=> $b } @coordinates[X1, X2];
-            Slic3r::debugf "Segment %d,%d - %d,%d (extents: %f, %f)\n", @coordinates, @line_c;
+            # TODO: here we should implement an "infill in direction of bridges" option
             
-            for (my $c = int($line_c[0] / $distance_between_lines) * $distance_between_lines; 
-                    $c <= $line_c[1]; $c += $distance_between_lines) {
-                next if $c < $line_c[0] || $c > $line_c[1];
-                my $i = sprintf('%.0f', $c / $distance_between_lines) - 1;
-                printf "CURRENT \$i = %d, \$c = %f\n", $i, $c;
+            # rotate surface as needed
+            $polygon = $polygon->rotate(@rotate)->move(@shift) if @rotate;
+            
+            # force 100% density for external surfaces
+            my $density = $surface->surface_type eq 'internal' ? $Slic3r::fill_density : 1;
+            next SURFACE unless $density > 0;
+            
+            my $distance_between_lines = $Slic3r::flow_width / $Slic3r::resolution / $density;
+            my $number_of_lines = ceil($max_print_dimension / $distance_between_lines);
+    
+            printf "distance = %f\n", $distance_between_lines;
+            printf "number_of_lines = %d\n", $number_of_lines;
+            
+            # this arrayref will hold intersection points of the fill grid with surface segments
+            my $points = [ map [], 0..$number_of_lines-1 ];
+            foreach my $line (map $self->_lines_from_mgp_points($_), @{ $polygon->polygons }) {
                 
-                # if the segment is parallel to our ray, there will be two intersection points
-                if ($line_c[0] == $line_c[1]) {
-                    Slic3r::debugf "  Segment is parallel!\n";
-                    push @{ $points->[$i] }, $coordinates[Y1], $coordinates[Y2];
-                    Slic3r::debugf "   intersections at %f (%d) = %f, %f\n", $c, $i, $points->[$i][-2], $points->[$i][-1];
-                } else {
-                    Slic3r::debugf "  Segment NOT parallel!\n";
-                    # one point of intersection
-                    push @{ $points->[$i] }, $coordinates[Y1] + ($coordinates[Y2] - $coordinates[Y1])
-                        * ($c - $coordinates[X1]) / ($coordinates[X2] - $coordinates[X1]);
-                    Slic3r::debugf "   intersection at %f (%d) = %f\n", $c, $i, $points->[$i][-1];
+                # find out the coordinates
+                my @coordinates = map @$_, @$line;
+                
+                # get the extents of the segment along the primary axis
+                my @line_c = sort { $a <=> $b } @coordinates[X1, X2];
+                Slic3r::debugf "Segment %d,%d - %d,%d (extents: %f, %f)\n", @coordinates, @line_c;
+                
+                for (my $c = int($line_c[0] / $distance_between_lines) * $distance_between_lines; 
+                        $c <= $line_c[1]; $c += $distance_between_lines) {
+                    next if $c < $line_c[0] || $c > $line_c[1];
+                    my $i = sprintf('%.0f', $c / $distance_between_lines) - 1;
+                    printf "CURRENT \$i = %d, \$c = %f\n", $i, $c;
+                    
+                    # if the segment is parallel to our ray, there will be two intersection points
+                    if ($line_c[0] == $line_c[1]) {
+                        Slic3r::debugf "  Segment is parallel!\n";
+                        push @{ $points->[$i] }, $coordinates[Y1], $coordinates[Y2];
+                        Slic3r::debugf "   intersections at %f (%d) = %f, %f\n", $c, $i, $points->[$i][-2], $points->[$i][-1];
+                    } else {
+                        Slic3r::debugf "  Segment NOT parallel!\n";
+                        # one point of intersection
+                        push @{ $points->[$i] }, $coordinates[Y1] + ($coordinates[Y2] - $coordinates[Y1])
+                            * ($c - $coordinates[X1]) / ($coordinates[X2] - $coordinates[X1]);
+                        Slic3r::debugf "   intersection at %f (%d) = %f\n", $c, $i, $points->[$i][-1];
+                    }
                 }
             }
-        }
-        
-        # sort and remove duplicates
-        for (my $i = 0; $i <= $#$points; $i++) {
-            my %h = map { sprintf("%.9f", $_) => 1 } @{ $points->[$i] };
-            $points->[$i] = [ sort { $a <=> $b } keys %h ];
-        }
-        
-        # generate extrusion paths
-        my (@paths, @path_points) = ();
-        my $direction = 0;
-        
-        my $stop_path = sub {
-            # defensive programming
-            if (@path_points == 1) {
-                #warn "There shouldn't be only one point in the current path";
+            
+            # sort and remove duplicates
+            for (my $i = 0; $i <= $#$points; $i++) {
+                my %h = map { sprintf("%.9f", $_) => 1 } @{ $points->[$i] };
+                $points->[$i] = [ sort { $a <=> $b } keys %h ];
             }
-                
-            # if we were constructing a path, stop it
-            push @paths, [ @path_points ] if @path_points > 1;
-            @path_points = ();
-        };
-        
-        # loop until we have spare points
-        CYCLE: while (scalar map(@$_, @$points) > 1) {
-            # loop through rows
-            ROW: for (my $i = 0; $i <= $#$points; $i++) {
-                my $row = $points->[$i] or next ROW;
-                Slic3r::debugf "\nProcessing row %d (direction: %d)...\n", $i, $direction;
-                if (!@$row) {
-                    Slic3r::debugf "  no points\n";
-                    $stop_path->();
-                    next ROW;
+            
+            # generate extrusion paths
+            my (@paths, @path_points) = ();
+            my $direction = 0;
+            
+            my $stop_path = sub {
+                # defensive programming
+                if (@path_points == 1) {
+                    #warn "There shouldn't be only one point in the current path";
                 }
-                Slic3r::debugf "  points = %s\n", join ', ', @$row if $Slic3r::debug;
-                
-                # coordinate of current row
-                my $c = ($i + 1) * $distance_between_lines;
-                
-                # need to start a path?
-                if (!@path_points) {
-                    Slic3r::debugf "  path starts at %d\n", $row->[0];
-                    push @path_points, [ $c, shift @$row ];
+                    
+                # if we were constructing a path, stop it
+                push @paths, [ @path_points ] if @path_points > 1;
+                @path_points = ();
+            };
+            
+            # loop until we have spare points
+            CYCLE: while (scalar map(@$_, @$points) > 1) {
+                # loop through rows
+                ROW: for (my $i = 0; $i <= $#$points; $i++) {
+                    my $row = $points->[$i] or next ROW;
+                    Slic3r::debugf "\nProcessing row %d (direction: %d)...\n", $i, $direction;
+                    if (!@$row) {
+                        Slic3r::debugf "  no points\n";
+                        $stop_path->();
+                        next ROW;
+                    }
+                    Slic3r::debugf "  points = %s\n", join ', ', @$row if $Slic3r::debug;
+                    
+                    # coordinate of current row
+                    my $c = ($i + 1) * $distance_between_lines;
+                    
+                    # need to start a path?
+                    if (!@path_points) {
+                        Slic3r::debugf "  path starts at %d\n", $row->[0];
+                        push @path_points, [ $c, shift @$row ];
+                    }
+                    
+                    my @search_points = @$row;
+                    @search_points = reverse @search_points if $direction == 1;
+                    my @connectable_points = $self->find_connectable_points($polygon, $path_points[-1], $c, [@search_points]);
+                    Slic3r::debugf "  ==> found %d connectable points = %s\n", scalar(@connectable_points),
+                        join ', ', @connectable_points if $Slic3r::debug;
+                    
+                    if (!@connectable_points && @path_points && $path_points[-1][0] != $c) {
+                        # no connectable in this row
+                        $stop_path->();
+                    }
+                    
+                    if (@connectable_points == 1 && $path_points[0][0] != $c 
+                        && (($connectable_points[0] == $row->[-1] && $direction == 0)
+                            || ($connectable_points[0] == $row->[0] && $direction == 1))) {
+                        $i--; # keep searching on current row in the opposite direction
+                    }
+                    
+                    foreach my $p (@connectable_points) {
+                        push @path_points, [ $c, $p ];
+                        @$row = grep $_ != $p, @$row;  # remove point from row
+                    }
+                    
+                    # invert direction
+                    $direction = $direction ? 0 : 1;
                 }
-                
-                my @search_points = @$row;
-                @search_points = reverse @search_points if $direction == 1;
-                my @connectable_points = $self->find_connectable_points($polygon, $path_points[-1], $c, [@search_points]);
-                Slic3r::debugf "  ==> found %d connectable points = %s\n", scalar(@connectable_points),
-                    join ', ', @connectable_points if $Slic3r::debug;
-                
-                if (!@connectable_points && @path_points && $path_points[-1][0] != $c) {
-                    # no connectable in this row
-                    $stop_path->();
-                }
-                
-                if (@connectable_points == 1 && $path_points[0][0] != $c 
-                    && (($connectable_points[0] == $row->[-1] && $direction == 0)
-                        || ($connectable_points[0] == $row->[0] && $direction == 1))) {
-                    $i--; # keep searching on current row in the opposite direction
-                }
-                
-                foreach my $p (@connectable_points) {
-                    push @path_points, [ $c, $p ];
-                    @$row = grep $_ != $p, @$row;  # remove point from row
-                }
-                
-                # invert direction
-                $direction = $direction ? 0 : 1;
+                $stop_path->() if @path_points;
             }
-            $stop_path->() if @path_points;
-        }
-        
-        # paths must be rotated back
-        if (@rotate) {
-            # TODO: this skips 2-points paths! we shouldn't create a mgp polygon
-            @paths = map $self->_mgp_from_points_ref($_)->move(map -$_, @shift)->rotate(-$rotate[0], $rotate[1])->points, @paths;
+            
+            # paths must be rotated back
+            if (@rotate) {
+                # TODO: this skips 2-points paths! we shouldn't create a mgp polygon
+                @paths = map $self->_mgp_from_points_ref($_)->move(map -$_, @shift)->rotate(-$rotate[0], $rotate[1])->points, @paths;
+            }
+            
+            push @path_collection, @paths;
         }
         
         # save into layer
-        FINISH: push @{ $layer->fills }, map Slic3r::ExtrusionPath->cast([ @$_ ]), @paths;
+        FINISH: push @{ $layer->fills }, Slic3r::ExtrusionPath::Collection->new(
+            paths => [ map Slic3r::ExtrusionPath->cast([ @$_ ]), @path_collection ],
+        );
     }
 }
 
diff --git a/lib/Slic3r/Geometry.pm b/lib/Slic3r/Geometry.pm
index f81e67122..b8a9d4091 100644
--- a/lib/Slic3r/Geometry.pm
+++ b/lib/Slic3r/Geometry.pm
@@ -124,6 +124,7 @@ sub nearest_point {
         if (!defined $distance || $d < $distance) {
             $nearest_point = $p;
             $distance = $d;
+            return $p if $distance < epsilon;
         }
     }
     return $nearest_point;
diff --git a/lib/Slic3r/Perimeter.pm b/lib/Slic3r/Perimeter.pm
index 69c49e1fd..cbfc1be5d 100644
--- a/lib/Slic3r/Perimeter.pm
+++ b/lib/Slic3r/Perimeter.pm
@@ -48,14 +48,17 @@ sub make_perimeter {
         }
         
         # create one more offset to be used as boundary for fill
-        push @{ $layer->fill_surfaces },
-            map Slic3r::Surface->new(
-                surface_type => $surface->surface_type,
-                contour      => Slic3r::Polyline::Closed->cast($_->{outer}),
-                holes        => [
-                    map Slic3r::Polyline::Closed->cast($_), @{$_->{holes}}
-                ],
-            ), $self->offset_polygon($perimeters[-1]),
+        push @{ $layer->fill_surfaces }, Slic3r::Surface::Collection->new(
+            surfaces => [
+                map Slic3r::Surface->new(
+                    surface_type => $surface->surface_type,
+                    contour      => Slic3r::Polyline::Closed->cast($_->{outer}),
+                    holes        => [
+                        map Slic3r::Polyline::Closed->cast($_), @{$_->{holes}}
+                    ],
+                ), $self->offset_polygon($perimeters[-1]),
+            ],
+        );
     }
     
     # generate paths for holes:
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index cd2fedcce..bc3aa3f8a 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -143,7 +143,7 @@ sub extrude_fills {
         $fill_extruder->make_fill($self, $layer);
         Slic3r::debugf "  generated %d paths: %s\n",
             scalar @{ $layer->fills },
-            join '  ', map $_->id, @{ $layer->fills } if $Slic3r::debug;
+            join '  ', map $_->id, map @{$_->paths}, @{ $layer->fills } if $Slic3r::debug;
     }
 }
 
@@ -286,7 +286,10 @@ sub export_gcode {
         }
         
         # extrude fills
-        $Extrude->($_, 'fill') for @{ $layer->fills };
+        for my $fill (@{ $layer->fills }) {
+            my @paths = $fill->shortest_path($last_pos);
+            $Extrude->($_, 'fill') for @paths;
+        }
     }
     
     # write end commands to file
diff --git a/lib/Slic3r/Surface/Collection.pm b/lib/Slic3r/Surface/Collection.pm
new file mode 100644
index 000000000..94c3df2cf
--- /dev/null
+++ b/lib/Slic3r/Surface/Collection.pm
@@ -0,0 +1,10 @@
+package Slic3r::Surface::Collection;
+use Moo;
+
+has 'surfaces' => (
+    is      => 'rw',
+    #isa     => 'ArrayRef[Slic3r::Surface]',
+    default => sub { [] },
+);
+
+1;