Optimization of travel paths for perimeters

lib/Slic3r.pm

@@ -8,6 +8,7 @@ sub debugf {
     printf @_ if $debug;
 }
 
+use Slic3r::ExtrusionLoop;
 use Slic3r::ExtrusionPath;
 use Slic3r::Fill;
 use Slic3r::Geometry;

lib/Slic3r/ExtrusionLoop.pm

@@ -0,0 +1,31 @@
+package Slic3r::ExtrusionLoop;
+use Moo;
+
+use XXX;
+
+extends 'Slic3r::Polyline::Closed';
+
+sub split_at {
+    my $self = shift;
+    my ($point) = @_;
+    
+    $point = Slic3r::Point->cast($point);
+    
+    # find index of point
+    my $i = -1;
+    for (my $n = 0; $n <= $#{$self->points}; $n++) {
+        if ($point->id eq $self->points->[$n]->id) {
+            $i = $n;
+            last;
+        }
+    }
+    die "Point not found" if $i == -1;
+    
+    my @new_points = ();
+    push @new_points, @{$self->points}[$i .. $#{$self->points}];
+    push @new_points, @{$self->points}[0 .. $i];
+    
+    return Slic3r::ExtrusionPath->new(points => [@new_points]);
+}
+
+1;

lib/Slic3r/ExtrusionPath.pm

@@ -3,4 +3,23 @@ use Moo;
 
 extends 'Slic3r::Polyline';
 
+sub clip_end {
+    my $self = shift;
+    my ($distance) = @_;
+    
+    while ($distance > 0) {
+        my $last_point = pop @{$self->points};
+        
+        my $last_segment_length = $last_point->distance_to($self->points->[-1]);
+        if ($last_segment_length <= $distance) {
+            $distance -= $last_segment_length;
+            next;
+        }
+        
+        my $new_point = Slic3r::Geometry::point_along_segment($last_point->p, $self->points->[-1]->p, $distance);
+        push @{$self->points}, Slic3r::Point->cast($new_point);
+        $distance = 0;
+    }
+}
+
 1;

lib/Slic3r/Geometry.pm

@@ -115,4 +115,33 @@ sub polygon_lines {
     return @lines;
 }
 
+sub nearest_point {
+    my ($point, $points) = @_;
+    
+    my ($nearest_point, $distance);
+    foreach my $p (@$points) {
+        my $d = distance_between_points($point, $p);
+        if (!defined $distance || $d < $distance) {
+            $nearest_point = $p;
+            $distance = $d;
+        }
+    }
+    return $nearest_point;
+}
+
+sub point_along_segment {
+    my ($p1, $p2, $distance) = @_;
+    
+    my $point = [ @$p1 ];
+    
+    my $line_length = sqrt( (($p2->[X] - $p1->[X])**2) + (($p2->[Y] - $p1->[Y])**2) );
+    for (X, Y) {
+        if ($p1->[$_] != $p2->[$_]) {
+            $point->[$_] = $p1->[$_] + ($p2->[$_] - $p1->[$_]) * $distance / $line_length;
+        }
+    }
+    
+    return $point;
+}
+
 1;

lib/Slic3r/Perimeter.pm

@@ -58,40 +58,18 @@ sub make_perimeter {
             ), $self->offset_polygon($perimeters[-1]),
     }
     
-    # generate paths for holes
+    # generate paths for holes:
     # we start from innermost loops (that is, external ones), do them
     # for all holes, than go on with inner loop and do that for all
-    # holes and so on
-    foreach my $hole (map @$_, values %holes) {
-        my @points = @$hole;
-        push @points, [ @{$points[0]} ];
-        # to avoid blobs, the first point is replaced by the point of
-        # the segment which is $Slic3r::flow_width / $Slic3r::resolution 
-        # away from it to avoid the extruder to get two times there
-        $points[0] = $self->_get_point_along_line($points[0], $points[1], 
-            $Slic3r::flow_width / $Slic3r::resolution);
-        push @{ $layer->perimeters }, Slic3r::ExtrusionPath->cast([@points]);
-    }
-    
-    # generate paths for contours
+    # holes and so on;
+    # then we generate paths for contours:
     # this time we do something different: we do contour loops for one
     # shape (that is, one original surface) at a time: we start from the
     # innermost loop (that is, internal one), then without interrupting 
     # our path we go onto the outer loop and continue; this should ensure
     # good surface quality
-    foreach my $polylines (values %contours) {
-        my @path_points = ();
-        foreach my $p (map $self->_mgp_from_points_ref($_), @$polylines) {
-            my $points = $p->points;
-            # to avoid blobs, the first point is replaced by the point of
-            # the segment which is $Slic3r::flow_width / $Slic3r::resolution 
-            # away from it to avoid the extruder to get two times there
-            push @$points, [ @{$points->[0]} ];
-            $points->[0] = $self->_get_point_along_line($points->[0], $points->[1], 
-                $Slic3r::flow_width / $Slic3r::resolution);
-            push @path_points, @$points;
-        }
-        push @{ $layer->perimeters }, Slic3r::ExtrusionPath->cast([ reverse @path_points ]);
+    foreach my $p (map @$_, values %holes, values %contours) {
+        push @{ $layer->perimeters }, Slic3r::ExtrusionLoop->cast($p);
     }
     
     # generate skirt on bottom layer
@@ -158,20 +136,4 @@ sub _mgp_from_polygons_ref {
     return $p;
 }
 
-sub _get_point_along_line {
-    my $self = shift;
-    my ($p1, $p2, $distance) = @_;
-    
-    my $point = [ @$p1 ];
-    
-    my $line_length = sqrt( (($p2->[X] - $p1->[X])**2) + (($p2->[Y] - $p1->[Y])**2) );
-    for (X, Y) {
-        if ($p1->[$_] != $p2->[$_]) {
-            $point->[$_] = $p1->[$_] + ($p2->[$_] - $p1->[$_]) * $distance / $line_length;
-        }
-    }
-    
-    return $point;
-}
-
 1;

lib/Slic3r/Polyline.pm

@@ -18,11 +18,11 @@ sub id {
 }
 
 sub cast {
-    my $self = shift;
+    my $class = shift;
     my ($points) = @_;
     
     @$points = map { ref $_ eq 'ARRAY' ? Slic3r::Point->cast($_) : $_ } @$points;
-    return __PACKAGE__->new(points => $points);
+    return $class->new(points => $points);
 }
 
 sub lines {
@@ -82,4 +82,15 @@ sub make_clockwise {
     $self->reverse_points if $self->is_counter_clockwise;
 }
 
+sub nearest_point_to {
+    my $self = shift;
+    my ($point) = @_;
+    
+    # get point as arrayref
+    $point = ref $point eq 'ARRAY' ? $point : $point->p;
+    
+    $point = Slic3r::Geometry::nearest_point($point, $self->p);
+    return Slic3r::Point->cast($point);
+}
+
 1;

lib/Slic3r/Print.pm

@@ -183,6 +183,7 @@ sub export_gcode {
     
     # make up a subroutine to generate G1 commands
     my $extrusion_distance = 0;
+    my $last_pos;  # on XY plane
     my $G1 = sub {
         my ($point, $z, $e, $comment) = @_;
         printf $fh "G1";
@@ -191,6 +192,7 @@ sub export_gcode {
             printf $fh " X%.${dec}f Y%.${dec}f", 
                 ($point->x * $Slic3r::resolution) + $shift[X], 
                 ($point->y * $Slic3r::resolution) + $shift[Y]; #**
+            $last_pos = $point->p;
         }
         if ($z) {
             printf $fh " Z%.${dec}f", $z;
@@ -269,7 +271,19 @@ sub export_gcode {
         $Extrude->($_, 'skirt') for @{ $layer->skirts };
         
         # extrude perimeters
-        $Extrude->($_, 'perimeter') for @{ $layer->perimeters };
+        for my $loop (@{ $layer->perimeters }) {
+            # find the point of the loop that is closest to the current extruder position
+            my $start_at = $last_pos ? $loop->nearest_point_to($last_pos) : $loop->points->[0];
+            
+            # split the loop at the starting point and make a path
+            my $extrusion_path = $loop->split_at($start_at);
+            
+            # clip the path to avoid the extruder to get exactly on the first point of the loop
+            $extrusion_path->clip_end($Slic3r::flow_width / $Slic3r::resolution);
+            
+            # extrude along the path
+            $Extrude->($extrusion_path, 'perimeter')
+        }
         
         # extrude fills
         $Extrude->($_, 'fill') for @{ $layer->fills };