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Refactoring: move bridge angle detection to a separate class for easier unit testing

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Alessandro Ranellucci 2014-04-07 23:18:11 +02:00
parent 93a7d87fc6
commit 119778caa9
3 changed files with 139 additions and 122 deletions
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126
lib/Slic3r/Layer/BridgeDetector.pm Normal file
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package Slic3r::Layer::BridgeDetector;
use Moo;
use Slic3r::Geometry qw(PI);
use Slic3r::Geometry::Clipper qw(intersection_pl);
has 'lower_slices' => (is => 'ro', required => 1); # ExPolygons or ExPolygonCollection
has 'perimeter_flow' => (is => 'ro', required => 1);
has 'infill_flow' => (is => 'ro', required => 1);
sub detect_angle {
my ($self, $expolygon) = @_;
my $grown = $expolygon->offset(+$self->perimeter_flow->scaled_width);
my @lower = @{$self->lower_slices}; # expolygons
# detect what edges lie on lower slices
my @edges = (); # polylines
foreach my $lower (@lower) {
# turn bridge contour and holes into polylines and then clip them
# with each lower slice's contour
my @clipped = @{intersection_pl([ map $_->split_at_first_point, @$grown ], [$lower->contour])};
if (@clipped == 2) {
# If the split_at_first_point() call above happens to split the polygon inside the clipping area
# we would get two consecutive polylines instead of a single one, so we use this ugly hack to
# recombine them back into a single one in order to trigger the @edges == 2 logic below.
# This needs to be replaced with something way better.
if (points_coincide($clipped[0][0], $clipped[-1][-1])) {
@clipped = (Slic3r::Polyline->new(@{$clipped[-1]}, @{$clipped[0]}));
}
if (points_coincide($clipped[-1][0], $clipped[0][-1])) {
@clipped = (Slic3r::Polyline->new(@{$clipped[0]}, @{$clipped[1]}));
}
}
push @edges, @clipped;
}
Slic3r::debugf " bridge has %d support(s)\n", scalar(@edges);
return undef if !@edges;
my $bridge_angle = undef;
if (0) {
require "Slic3r/SVG.pm";
Slic3r::SVG::output("bridge_$expolygon.svg",
expolygons => [ $expolygon ],
red_expolygons => [ @lower ],
polylines => [ @edges ],
);
}
if (@edges == 2) {
my @chords = map Slic3r::Line->new($_->[0], $_->[-1]), @edges;
my @midpoints = map $_->midpoint, @chords;
my $line_between_midpoints = Slic3r::Line->new(@midpoints);
$bridge_angle = Slic3r::Geometry::rad2deg_dir($line_between_midpoints->direction);
} elsif (@edges == 1) {
# TODO: this case includes both U-shaped bridges and plain overhangs;
# we need a trapezoidation algorithm to detect the actual bridged area
# and separate it from the overhang area.
# in the mean time, we're treating as overhangs all cases where
# our supporting edge is a straight line
if (@{$edges[0]} > 2) {
my $line = Slic3r::Line->new($edges[0]->[0], $edges[0]->[-1]);
$bridge_angle = Slic3r::Geometry::rad2deg_dir($line->direction);
}
} elsif (@edges) {
# inset the bridge expolygon; we'll use this one to clip our test lines
my $inset = $expolygon->offset_ex($self->infill_flow->scaled_width);
# detect anchors as intersection between our bridge expolygon and the lower slices
my $anchors = intersection_ex(
$grown,
[ map @$_, @lower ],
1, # safety offset required to avoid Clipper from detecting empty intersection while Boost actually found some @edges
);
if (@$anchors) {
# we'll now try several directions using a rudimentary visibility check:
# bridge in several directions and then sum the length of lines having both
# endpoints within anchors
my %directions = (); # angle => score
my $angle_increment = PI/36; # 5°
my $line_increment = $self->infill_flow->scaled_width;
for (my $angle = 0; $angle <= PI; $angle += $angle_increment) {
# rotate everything - the center point doesn't matter
$_->rotate($angle, [0,0]) for @$inset, @$anchors;
# generate lines in this direction
my $bounding_box = Slic3r::Geometry::BoundingBox->new_from_points([ map @$_, map @$_, @$anchors ]);
my @lines = ();
for (my $x = $bounding_box->x_min; $x <= $bounding_box->x_max; $x += $line_increment) {
push @lines, Slic3r::Polyline->new([$x, $bounding_box->y_min], [$x, $bounding_box->y_max]);
}
my @clipped_lines = map Slic3r::Line->new(@$_), @{ intersection_pl(\@lines, [ map @$_, @$inset ]) };
# remove any line not having both endpoints within anchors
# NOTE: these calls to contains_point() probably need to check whether the point
# is on the anchor boundaries too
@clipped_lines = grep {
my $line = $_;
!(first { $_->contains_point($line->a) } @$anchors)
&& !(first { $_->contains_point($line->b) } @$anchors);
} @clipped_lines;
# sum length of bridged lines
$directions{-$angle} = sum(map $_->length, @clipped_lines) // 0;
}
# this could be slightly optimized with a max search instead of the sort
my @sorted_directions = sort { $directions{$a} <=> $directions{$b} } keys %directions;
# the best direction is the one causing most lines to be bridged
$bridge_angle = Slic3r::Geometry::rad2deg_dir($sorted_directions[-1]);
}
}
Slic3r::debugf " Optimal infill angle is %d degrees\n", $bridge_angle
if defined $bridge_angle;
return $bridge_angle;
}
1;