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Improvements to bridge angle detection: use coverage test for all cases (including two-sided bridges and C-shaped bridges) and check for all angles equal to directions of bridge sides

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This commit is contained in:
Alessandro Ranellucci 2014-04-28 22:15:40 +02:00
parent 24571612c7
commit f7421053cc
1 changed files with 86 additions and 89 deletions
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175
lib/Slic3r/Layer/BridgeDetector.pm
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@ -55,101 +55,98 @@ sub detect_angle {
my @edges = @{$self->_edges};
my $anchors = $self->_anchors;
if (@edges == 2) {
my @chords = map Slic3r::Line->new($_->[0], $_->[-1]), @edges;
my @midpoints = map $_->midpoint, @chords;
my $line_between_midpoints = Slic3r::Line->new(@midpoints);
$self->angle($line_between_midpoints->direction);
} elsif (@edges == 1 && !$edges[0][0]->coincides_with($edges[0][-1])) {
# Don't use this logic if $edges[0] is actually a closed loop
# TODO: this case includes both U-shaped bridges and plain overhangs;
# we need a trapezoidation algorithm to detect the actual bridged area
# and separate it from the overhang area.
# in the mean time, we're treating as overhangs all cases where
# our supporting edge is a straight line
if (@{$edges[0]} > 2) {
my $line = Slic3r::Line->new($edges[0]->[0], $edges[0]->[-1]);
$self->angle($line->direction);
}
} elsif (@edges) {
# Outset the bridge expolygon by half the amount we used for detecting anchors;
# we'll use this one to clip our test lines and be sure that their endpoints
# are inside the anchors and not on their contours leading to false negatives.
my $clip_area = $self->expolygon->offset_ex(+$self->extrusion_width/2);
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_coverage = (); # angle => score
my %directions_avg_length = (); # angle => score
my $line_increment = $self->extrusion_width;
for (my $angle = 0; $angle < PI; $angle += $self->resolution) {
my $my_clip_area = [ map $_->clone, @$clip_area ];
my $my_anchors = [ map $_->clone, @$anchors ];
# rotate everything - the center point doesn't matter
$_->rotate(-$angle, [0,0]) for @$my_clip_area, @$my_anchors;
# generate lines in this direction
my $bounding_box = Slic3r::Geometry::BoundingBox->new_from_points([ map @$_, map @$_, @$my_anchors ]);
my @lines = ();
for (my $y = $bounding_box->y_min; $y <= $bounding_box->y_max; $y+= $line_increment) {
push @lines, Slic3r::Polyline->new(
[$bounding_box->x_min, $y],
[$bounding_box->x_max, $y],
);
}
my @clipped_lines = map Slic3r::Line->new(@$_), @{ intersection_pl(\@lines, [ map @$_, @$my_clip_area ]) };
# 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) } @$my_anchors)
&& (first { $_->contains_point($line->b) } @$my_anchors);
} @clipped_lines;
my @lengths = map $_->length, @clipped_lines;
# sum length of bridged lines
$directions_coverage{$angle} = sum(@lengths) // 0;
# max length of bridged lines
$directions_avg_length{$angle} = @lengths ? (max(@lengths)) : -1;
}
# if no direction produced coverage, then there's no bridge direction
return undef if !defined first { $_ > 0 } values %directions_coverage;
# the best direction is the one causing most lines to be bridged (thus most coverage)
# and shortest max line length
my @sorted_directions = sort {
my $cmp;
my $coverage_diff = $directions_coverage{$a} - $directions_coverage{$b};
if (abs($coverage_diff) < $self->extrusion_width) {
$cmp = $directions_avg_length{$b} <=> $directions_avg_length{$a};
} else {
$cmp = ($coverage_diff > 0) ? 1 : -1;
}
$cmp;
} keys %directions_coverage;
$self->angle($sorted_directions[-1]);
}
if (!@$anchors) {
$self->angle(undef);
return undef;
}
if (defined $self->angle) {
if ($self->angle >= PI) {
$self->angle($self->angle - PI);
# Outset the bridge expolygon by half the amount we used for detecting anchors;
# we'll use this one to clip our test lines and be sure that their endpoints
# are inside the anchors and not on their contours leading to false negatives.
my $clip_area = $self->expolygon->offset_ex(+$self->extrusion_width/2);
# 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
# we test angles according to configured resolution
my @angles = map { $_*$self->resolution } 0..(PI/$self->resolution);
# we also test angles of each bridge contour
push @angles, map $_->direction, map @{$_->lines}, @{$self->expolygon};
# we also test angles of each open supporting edge
# (this finds the optimal angle for C-shaped supports)
push @angles, map Slic3r::Line->new($_->first_point, $_->last_point)->direction,
grep { !$_->first_point->coincides_with($_->last_point) }
@edges;
my %directions_coverage = (); # angle => score
my %directions_avg_length = (); # angle => score
my $line_increment = $self->extrusion_width;
my %unique_angles = map { $_ => 1 } @angles;
for my $angle (keys %unique_angles) {
my $my_clip_area = [ map $_->clone, @$clip_area ];
my $my_anchors = [ map $_->clone, @$anchors ];
# rotate everything - the center point doesn't matter
$_->rotate(-$angle, [0,0]) for @$my_clip_area, @$my_anchors;
# generate lines in this direction
my $bounding_box = Slic3r::Geometry::BoundingBox->new_from_points([ map @$_, map @$_, @$my_anchors ]);
my @lines = ();
for (my $y = $bounding_box->y_min; $y <= $bounding_box->y_max; $y+= $line_increment) {
push @lines, Slic3r::Polyline->new(
[$bounding_box->x_min, $y],
[$bounding_box->x_max, $y],
);
}
Slic3r::debugf " Optimal infill angle is %d degrees\n", rad2deg($self->angle);
my @clipped_lines = map Slic3r::Line->new(@$_), @{ intersection_pl(\@lines, [ map @$_, @$my_clip_area ]) };
# 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) } @$my_anchors)
&& (first { $_->contains_point($line->b) } @$my_anchors);
} @clipped_lines;
my @lengths = map $_->length, @clipped_lines;
# sum length of bridged lines
$directions_coverage{$angle} = sum(@lengths) // 0;
# max length of bridged lines
$directions_avg_length{$angle} = @lengths ? (max(@lengths)) : -1;
}
# if no direction produced coverage, then there's no bridge direction
return undef if !defined first { $_ > 0 } values %directions_coverage;
# the best direction is the one causing most lines to be bridged (thus most coverage)
# and shortest max line length
my @sorted_directions = sort {
my $cmp;
my $coverage_diff = $directions_coverage{$a} - $directions_coverage{$b};
if (abs($coverage_diff) < $self->extrusion_width) {
$cmp = $directions_avg_length{$b} <=> $directions_avg_length{$a};
} else {
$cmp = ($coverage_diff > 0) ? 1 : -1;
}
$cmp;
} keys %directions_coverage;
$self->angle($sorted_directions[-1]);
if ($self->angle >= PI) {
$self->angle($self->angle - PI);
}
Slic3r::debugf " Optimal infill angle is %d degrees\n", rad2deg($self->angle);
return $self->angle;
}