Don't extrude acute angles

lib/Slic3r/ExtrusionPath.pm

@@ -3,6 +3,8 @@ use Moo;
 
 extends 'Slic3r::Polyline';
 
+use constant PI => 4 * atan2(1, 1);
+
 sub clip_end {
     my $self = shift;
     my ($distance) = @_;
@@ -34,4 +36,36 @@ sub reverse {
     @{$self->points} = reverse @{$self->points};
 }
 
+sub split_at_acute_angles {
+    my $self = shift;
+    
+    # calculate angle limit
+    my $angle_limit = abs(Slic3r::Geometry::deg2rad(40));
+    my @points = @{$self->p};
+    
+    my @paths = ();
+    
+    # take first two points
+    my @p = splice @points, 0, 2;
+    
+    # loop until we have one spare point
+    while (my $p3 = shift @points) {
+        my $angle = abs(Slic3r::Geometry::angle3points($p[-1], $p[-2], $p3));
+        $angle = 2*PI - $angle if $angle > PI;
+        
+        if ($angle < $angle_limit) {
+            # if the angle between $p[-2], $p[-1], $p3 is too acute
+            # then consider $p3 only as a starting point of a new
+            # path and stop the current one as it is
+            push @paths, __PACKAGE__->cast([@p]);
+            @p = ($p3);
+            push @p, grep $_, shift @points or last;
+        } else {
+            push @p, $p3;
+        }
+    }
+    push @paths, __PACKAGE__->cast([@p]) if @p > 1;
+    return @paths;
+}
+
 1;

lib/Slic3r/ExtrusionPath/Collection.pm

@@ -52,4 +52,11 @@ sub shortest_path {
     return @paths;
 }
 
+sub cleanup {
+    my $self = shift;
+    
+    # split paths at angles that are too acute to be printed as they will cause blobs
+    @{$self->paths} = map $_->split_at_acute_angles, @{$self->paths};
+}
+
 1;

lib/Slic3r/Fill/Rectilinear.pm

@@ -170,9 +170,10 @@ sub make_fill {
         }
         
         # save into layer
-        FINISH: push @{ $layer->fills }, Slic3r::ExtrusionPath::Collection->new(
+        push @{ $layer->fills }, Slic3r::ExtrusionPath::Collection->new(
             paths => [ map Slic3r::ExtrusionPath->cast([ @$_ ]), @path_collection ],
         );
+        $layer->fills->[-1]->cleanup;
     }
 }
 

lib/Slic3r/SVG.pm

@@ -8,12 +8,12 @@ use constant X => 0;
 use constant Y => 1;
 
 sub factor {
-    return $Slic3r::resolution * 10;
+    return $Slic3r::resolution * 100;
 }
 
 sub svg {
     my ($print) = @_;
-    
+    $print ||= Slic3r::Print->new(x_length => 200 / $Slic3r::resolution, y_length => 200 / $Slic3r::resolution);
     return SVG->new(width => $print->max_length * factor(), height => $print->max_length * factor());
 }
 
@@ -56,7 +56,8 @@ sub output_points {
 }
 
 sub output_polygons {
-    my ($print, $filename, $polygons) = @_;
+    my ($print, $filename, $polygons, $type) = @_;
+    $type ||= 'polygon';
     
     my $svg = svg($print);
     my $g = $svg->group(
@@ -72,7 +73,7 @@ sub output_polygons {
             'y' => [ map($_->[Y] * factor(), @$polygon) ],
             -type => 'polygon',
         );
-        $g->polygon(
+        $g->$type(
             %$path,
         );
     }
@@ -80,6 +81,10 @@ sub output_polygons {
     write_svg($svg, $filename);
 }
 
+sub output_polylines {
+    return output_polygons(@_, 'polyline');
+}
+
 sub output_lines {
     my ($print, $filename, $lines) = @_;