More unit tests for bridge angle detection

lib/Slic3r/Layer/BridgeDetector.pm

@@ -5,9 +5,9 @@ use List::Util qw(first sum);
 use Slic3r::Geometry qw(PI scaled_epsilon rad2deg epsilon);
 use Slic3r::Geometry::Clipper qw(intersection_pl intersection_ex);
 
-has 'lower_slices'      => (is => 'ro', required => 1);  # ExPolygons or ExPolygonCollection
+has 'lower_slices'      => (is => 'rw', required => 1);  # ExPolygons or ExPolygonCollection
-has 'perimeter_flow'    => (is => 'ro', required => 1);
+has 'perimeter_flow'    => (is => 'rw', required => 1);
-has 'infill_flow'       => (is => 'ro', required => 1);
+has 'infill_flow'       => (is => 'rw', required => 1);
 
 sub detect_angle {
     my ($self, $expolygon) = @_;
@@ -30,7 +30,7 @@ sub detect_angle {
     
     if (0) {
         require "Slic3r/SVG.pm";
-        Slic3r::SVG::output("bridge_$expolygon.svg",
+        Slic3r::SVG::output("bridge.svg",
             expolygons      => [ $expolygon ],
             red_expolygons  => [ @lower ],
             polylines       => [ @edges ],
@@ -42,7 +42,7 @@ sub detect_angle {
         my @midpoints = map $_->midpoint, @chords;
         my $line_between_midpoints = Slic3r::Line->new(@midpoints);
         $bridge_angle = $line_between_midpoints->direction;
-    } elsif (@edges == 1 && $edges[0][0]->coincides_with($edges[0][-1])) {
+    } elsif (@edges == 1 && !$edges[0][0]->coincides_with($edges[0][-1])) {
         # Don't use this logic if $edges[0] is actually a closed loop
         # TODO: this case includes both U-shaped bridges and plain overhangs;
         # we need a trapezoidation algorithm to detect the actual bridged area

lib/Slic3r/Polygon.pm

@@ -61,18 +61,23 @@ sub clip_as_polyline {
     $self_pl->[0]->translate(1, 0);
     
     my @polylines = @{intersection_pl([$self_pl], $polygons)};
-    if (@polylines == 2) {
+    if (@polylines == 1) {
+        if ($polylines[0][0]->coincides_with($self_pl->[0])) {
+            # compensate the above workaround for Clipper bug
+            $polylines[0][0]->translate(-1, 0);
+        }
+    } elsif (@polylines == 2) {
         # If the split_at_first_point() call above happens to split the polygon inside the clipping area
         # we would get two consecutive polylines instead of a single one, so we use this ugly hack to 
         # recombine them back into a single one in order to trigger the @edges == 2 logic below.
         # This needs to be replaced with something way better.
-        if ($polylines[0][-1]->coincides_width($self_pl->[-1]) && $polylines[-1][0]->coincides_width($self_pl->[0])) {
+        if ($polylines[0][-1]->coincides_with($self_pl->[-1]) && $polylines[-1][0]->coincides_width($self_pl->[0])) {
             my $p = $polylines[0]->clone;
             $p->pop_back;
             $p->append(@{$polylines[-1]});
             return [$p];
         }
-        if ($polylines[0][0]->coincides_width($self_pl->[0]) && $polylines[-1][-1]->coincides_width($self_pl->[-1])) {
+        if ($polylines[0][0]->coincides_with($self_pl->[0]) && $polylines[-1][-1]->coincides_width($self_pl->[-1])) {
             my $p = $polylines[-1]->clone;
             $p->pop_back;
             $p->append(@{$polylines[0]});

t/bridges.t

@@ -1,4 +1,4 @@
-use Test::More tests => 2;
+use Test::More tests => 4;
 use strict;
 use warnings;
 
@@ -9,10 +9,15 @@ BEGIN {
 
 use List::Util qw(first);
 use Slic3r;
-use Slic3r::Geometry qw(scale epsilon rad2deg);
+use Slic3r::Geometry qw(scale epsilon rad2deg PI);
 use Slic3r::Test;
 
 my $flow = Slic3r::Flow->new(width => 0.5, spacing => 0.45, nozzle_diameter => 0.5);
+my $bd = Slic3r::Layer::BridgeDetector->new(
+    lower_slices    => [],
+    perimeter_flow  => $flow,
+    infill_flow     => $flow,
+);
 
 {
     my $test = sub {
@@ -27,17 +32,54 @@ my $flow = Slic3r::Flow->new(width => 0.5, spacing => 0.45, nozzle_diameter => 0
         my $bridge = $lower->[1]->clone;
         $bridge->reverse;
         $bridge = Slic3r::ExPolygon->new($bridge);
-        my $bd = Slic3r::Layer::BridgeDetector->new(
+        $bd->lower_slices([$lower]);
-            lower_slices    => [$lower],
-            perimeter_flow  => $flow,
-            infill_flow     => $flow,
-        );
         
-        ok abs(rad2deg($bd->detect_angle($bridge)) - $expected_angle) < epsilon, 'correct bridge angle detected';
+        ok check_angle($bd->detect_angle($bridge), $expected_angle), 'correct bridge angle for O-shaped overhang';
     };
     
     $test->([20,10], 90);
     $test->([10,20],  0);
 }
 
+{
+    my $bridge = Slic3r::ExPolygon->new(
+        Slic3r::Polygon->new_scale([0,0], [20,0], [20,10], [0,10]),
+    );
+    my $lower = [
+        Slic3r::ExPolygon->new(
+            Slic3r::Polygon->new_scale([-2,0], [0,0], [0,10], [-2,10]),
+        ),
+    ];
+    $_->translate(scale 20, scale 20) for $bridge, @$lower; # avoid negative coordinates for easier SVG preview
+    
+    $lower->[1] = $lower->[0]->clone;
+    $lower->[1]->translate(scale 22, 0);
+    
+    $bd->lower_slices($lower);
+    ok check_angle($bd->detect_angle($bridge), 0), 'correct bridge angle for two-sided bridge';
+}
+
+{
+    my $bridge = Slic3r::ExPolygon->new(
+        Slic3r::Polygon->new_scale([0,0], [20,0], [10,10], [0,10]),
+    );
+    my $lower = [
+        Slic3r::ExPolygon->new(
+            Slic3r::Polygon->new_scale([0,0], [0,10], [10,10], [10,12], [-2,12], [-2,-2], [22,-2], [22,0]),
+        ),
+    ];
+    $_->translate(scale 20, scale 20) for $bridge, @$lower; # avoid negative coordinates for easier SVG preview
+    
+    $bd->lower_slices($lower);
+    ok check_angle($bd->detect_angle($bridge), 135), 'correct bridge angle for C-shaped overhang';
+}
+
+sub check_angle {
+    my ($result, $expected) = @_;
+    
+    # our epsilon is equal to the steps used by the bridge detection algorithm
+    ###use XXX; YYY [ rad2deg($result), $expected ];
+    return defined $result && abs(rad2deg($result) - $expected) < rad2deg(PI/36);
+}
+
 __END__