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Rewrite avoid_crossing_perimeters() to fix a regression and get better performance by choosing regular points along contours. #1531

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This commit is contained in:
Alessandro Ranellucci 2013-12-22 18:47:39 +01:00
parent ca16567ba9
commit e403dc16ae
3 changed files with 251 additions and 220 deletions
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2
lib/Slic3r/GCode.pm
View file

@ -456,7 +456,7 @@ sub _plan {
# append the actual path and return
$self->speed('travel');
# use G1 because we rely on paths being straight (G0 may make round paths)
$gcode .= join '', map $self->G1($_->[B], undef, 0, $comment || ""), @travel;
$gcode .= join '', map $self->G1($_->b, undef, 0, $comment || ""), @travel;
return $gcode;
}

467
lib/Slic3r/GCode/MotionPlanner.pm
View file

@ -1,23 +1,18 @@
package Slic3r::GCode::MotionPlanner;
use Moo;
has 'islands' => (is => 'ro', required => 1);
has 'no_internal' => (is => 'ro');
has 'last_crossings'=> (is => 'rw');
has '_inner' => (is => 'rw', default => sub { [] }); # arrayref of arrayrefs of expolygons
has '_outer' => (is => 'rw', default => sub { [] }); # arrayref of arrayrefs of polygons
has '_contours_ex' => (is => 'rw', default => sub { [] }); # arrayref of arrayrefs of expolygons
has '_pointmap' => (is => 'rw', default => sub { {} }); # { id => $point }
has '_edges' => (is => 'rw', default => sub { {} }); # node_idx => { node_idx => distance, ... }
has '_crossing_edges' => (is => 'rw', default => sub { {} }); # edge_idx => bool
has '_tolerance' => (is => 'lazy');
has 'islands' => (is => 'ro', required => 1); # arrayref of ExPolygons
has 'internal' => (is => 'ro', default => sub { 1 });
has '_space' => (is => 'ro', default => sub { Slic3r::GCode::MotionPlanner::ConfigurationSpace->new });
has '_inner' => (is => 'ro', default => sub { [] }); # arrayref of ExPolygons
has '_tolerance' => (is => 'lazy');
use List::Util qw(first);
use List::Util qw(first max);
use Slic3r::Geometry qw(A B scale epsilon);
use Slic3r::Geometry::Clipper qw(diff_ex offset);
use Slic3r::Geometry::Clipper qw(offset offset_ex diff_ex);
# clearance (in mm) from the perimeters
has '_inner_margin' => (is => 'ro', default => sub { scale 0.5 });
has '_inner_margin' => (is => 'ro', default => sub { scale 1 });
has '_outer_margin' => (is => 'ro', default => sub { scale 2 });
# this factor weigths the crossing of a perimeter
@ -27,9 +22,9 @@ has '_outer_margin' => (is => 'ro', default => sub { scale 2 });
# follow if we decided to cross the perimeter.
# a nearly-infinite value for this will only permit
# perimeter crossing when there's no alternative path.
use constant CROSSING_FACTOR => 20;
use constant CROSSING_PENALTY => 20;
use constant INFINITY => 'inf';
use constant POINT_DISTANCE => 10; # unscaled
sub _build__tolerance { scale epsilon }
@ -37,191 +32,101 @@ sub _build__tolerance { scale epsilon }
sub BUILD {
my $self = shift;
my $edges = $self->_edges;
my $crossing_edges = $self->_crossing_edges;
# simplify islands
@{$self->islands} = map $_->simplify($self->_inner_margin), @{$self->islands};
my $point_distance = scale POINT_DISTANCE;
my $nodes = $self->_space->nodes;
my $edges = $self->_space->edges;
# process individual islands
for my $i (0 .. $#{$self->islands}) {
# offset the island inwards to make the boundaries for internal movements
# so that no motion along external perimeters happens
$self->_inner->[$i] = $self->no_internal
? []
: $self->islands->[$i]->offset_ex(-$self->_inner_margin);
for my $i (0 .. $#{$self->islands}) {
my $expolygon = $self->islands->[$i];
# find external margin
my $outer = offset([ @$expolygon ], +$self->_outer_margin);
my @outer_points = map @{$_->equally_spaced_points($point_distance)}, @$outer;
# offset the island outwards to make the boundaries for external movements
$self->_outer->[$i] = offset([ $self->islands->[$i]->contour ], $self->_outer_margin);
# add outer points to graph
my $o_outer = $self->_space->add_nodes(@outer_points);
# if internal motion is enabled, build a set of utility expolygons representing
# the outer boundaries (as contours) and the inner boundaries (as holes). whenever
# we jump from a hole to a contour or viceversa, we know we're crossing a perimeter
if (!$self->no_internal) {
$self->_contours_ex->[$i] = diff_ex(
$self->_outer->[$i],
[ map $_->contour, @{$self->_inner->[$i]} ],
# find pairs of visible outer points and add them to the graph
for my $i (0 .. $#outer_points) {
for my $j (($i+1) .. $#outer_points) {
my ($a, $b) = ($outer_points[$i], $outer_points[$j]);
my $line = Slic3r::Line->new($a, $b);
# outer points are visible when their line has empty intersection with islands
my $intersection = Boost::Geometry::Utils::multi_polygon_multi_linestring_intersection(
[ map $_->pp, @{$self->islands} ],
[ $line->pp ],
);
if (!@$intersection) {
$self->_space->add_edge($i+$o_outer, $j+$o_outer, $line->length);
}
}
}
if ($self->internal) {
# find internal margin
my $inner = offset_ex([ @$expolygon ], -$self->_inner_margin);
push @{ $self->_inner }, @$inner;
my @inner_points = map @{$_->equally_spaced_points($point_distance)}, map @$_, @$inner;
# add points to graph and get their offset
my $o_inner = $self->_space->add_nodes(@inner_points);
# find pairs of visible inner points and add them to the graph
for my $i (0 .. $#inner_points) {
for my $j (($i+1) .. $#inner_points) {
my ($a, $b) = ($inner_points[$i], $inner_points[$j]);
my $line = Slic3r::Line->new($a, $b);
# turn $inner into an ExPolygonCollection and use $inner->contains_line()
if (first { $_->encloses_line($line, $self->_tolerance) } @$inner) {
$self->_space->add_edge($i+$o_inner, $j+$o_inner, $line->length);
}
}
}
# generate the stripe around slice contours
my $contour = diff_ex(
$outer,
[ map @$_, @$inner ],
);
# lines enclosed in inner expolygons are visible
$self->_add_expolygon($_) for @{ $self->_inner->[$i] };
# lines enclosed in expolygons covering perimeters are visible
# (but discouraged)
$self->_add_expolygon($_, 1) for @{ $self->_contours_ex->[$i] };
}
}
{
my @outer = (map @$_, @{$self->_outer});
my @outer_ex = map Slic3r::ExPolygon->new($_), @outer; # build ExPolygons for Boost
# lines of outer polygons connect visible points
for my $i (0 .. $#outer) {
foreach my $line (@{$outer[$i]->lines}) {
my $dist = $line->length;
$edges->{$line->a}{$line->b} = $dist;
$edges->{$line->b}{$line->a} = $dist;
}
}
# lines connecting outer polygons are visible
for my $i (0 .. $#outer) {
for my $j (($i+1) .. $#outer) {
for my $m (0 .. $#{$outer[$i]}) {
for my $n (0 .. $#{$outer[$j]}) {
my $line = Slic3r::Line->new($outer[$i][$m], $outer[$j][$n]);
if (!@{Boost::Geometry::Utils::multi_polygon_multi_linestring_intersection([ map $_->pp, @outer_ex ], [$line->pp])}) {
# this line does not cross any polygon
my $dist = $line->length;
$edges->{$outer[$i][$m]}{$outer[$j][$n]} = $dist;
$edges->{$outer[$j][$n]}{$outer[$i][$m]} = $dist;
}
# find pairs of visible points in this area and add them to the graph
for my $i (0 .. $#inner_points) {
for my $j (0 .. $#outer_points) {
my ($a, $b) = ($inner_points[$i], $outer_points[$j]);
my $line = Slic3r::Line->new($a, $b);
# turn $contour into an ExPolygonCollection and use $contour->contains_line()
if (first { $_->encloses_line($line, $self->_tolerance) } @$contour) {
$self->_space->add_edge($i+$o_inner, $j+$o_outer, $line->length * CROSSING_PENALTY);
}
}
}
}
}
# lines connecting inner polygons contours are visible but discouraged
if (!$self->no_internal) {
my @inner = (map $_->contour, map @$_, @{$self->_inner});
my @inner_ex = map Slic3r::ExPolygon->new($_), @inner; # build ExPolygons for Boost
for my $i (0 .. $#inner) {
for my $j (($i+1) .. $#inner) {
for my $m (0 .. $#{$inner[$i]}) {
for my $n (0 .. $#{$inner[$j]}) {
my $line = Slic3r::Line->new($inner[$i][$m], $inner[$j][$n]);
if (!@{Boost::Geometry::Utils::multi_polygon_multi_linestring_intersection([ map $_->pp, @inner_ex ], [$line->pp])}) {
# this line does not cross any polygon
my $dist = $line->length * CROSSING_FACTOR;
$edges->{$inner[$i][$m]}{$inner[$j][$n]} = $dist;
$edges->{$inner[$j][$n]}{$inner[$i][$m]} = $dist;
$crossing_edges->{$inner[$i][$m]}{$inner[$j][$n]} = 1;
$crossing_edges->{$inner[$j][$n]}{$inner[$i][$m]} = 1;
}
}
}
}
}
}
$self->_pointmap({
map +("$_" => $_),
(map @$_, map @$_, map @$_, @{$self->_inner}),
(map @$_, map @$_, @{$self->_outer}),
(map @$_, map @$_, map @$_, @{$self->_contours_ex}),
});
# since Perl has no infinity symbol and we don't want to overcomplicate
# the Dijkstra algorithm with string constants or -1 values
$self->_space->_infinity(10 * (max(map values %$_, values %{$self->_space->edges}) // 0));
if (0) {
my @lines = ();
my %lines = ();
for my $i (keys %{$self->_edges}) {
for my $j (keys %{$self->_edges->{$i}}) {
next if $lines{join '_', sort $i, $j};
push @lines, [ map $self->_pointmap->{$_}, $i, $j ];
$lines{join '_', sort $i, $j} = 1;
}
}
require "Slic3r/SVG.pm";
Slic3r::SVG::output("space.svg",
lines => \@lines,
points => [ values %{$self->_pointmap} ],
no_arrows => 1,
expolygons => $self->islands,
#red_polygons => [ map @{$_->holes}, map @$_, @{$self->_inner} ],
#white_polygons => [ map @$_, @{$self->_outer} ],
lines => $self->_space->get_lines,
points => $self->_space->nodes,
);
printf "%d islands\n", scalar @{$self->islands};
eval "use Devel::Size";
print "MEMORY USAGE:\n";
printf " %-19s = %.1fMb\n", $_, Devel::Size::total_size($self->$_)/1024/1024
for qw(_inner _outer _contours_ex _pointmap _edges _crossing_edges islands last_crossings);
for qw(_space islands);
printf " %-19s = %.1fMb\n", $_, Devel::Size::total_size($self->_space->$_)/1024/1024
for qw(nodes edges);
printf " %-19s = %.1fMb\n", 'self', Devel::Size::total_size($self)/1024/1024;
}
}
# given an expolygon, this subroutine connects all its visible points
sub _add_expolygon {
my $self = shift;
my ($expolygon, $crosses_perimeter) = @_;
my $edges = $self->_edges;
my $crossing_edges = $self->_crossing_edges;
my @points = map @$_, @$expolygon;
for my $i (0 .. $#points) {
for my $j (($i+1) .. $#points) {
my $line = Slic3r::Line->new($points[$i], $points[$j]);
if ($expolygon->encloses_line($line, $self->_tolerance)) {
my $dist = $line->length * ($crosses_perimeter ? CROSSING_FACTOR : 1);
$edges->{$points[$i]}{$points[$j]} = $dist;
$edges->{$points[$j]}{$points[$i]} = $dist;
$crossing_edges->{$points[$i]}{$points[$j]} = 1;
$crossing_edges->{$points[$j]}{$points[$i]} = 1;
}
}
}
}
sub find_node {
my $self = shift;
my ($point, $near_to) = @_;
# for optimal pathing, we should check visibility from $point to all $candidates, and then
# choose the one that is nearest to $near_to among the visible ones; however this is probably too slow
# if we're inside a hole, move to a point on hole;
{
my $polygon = first { $_->encloses_point($point) } (map @{$_->holes}, map @$_, @{$self->_inner});
return $point->nearest_point([ @$polygon ]) if $polygon;
}
# if we're inside an expolygon move to a point on contour or holes
{
my $expolygon = first { $_->encloses_point_quick($point) } (map @$_, @{$self->_inner});
return $point->nearest_point([ map @$_, @$expolygon ]) if $expolygon;
}
{
my $outer_polygon_idx;
if (!$self->no_internal) {
# look for an outer expolygon whose contour contains our point
$outer_polygon_idx = first { first { $_->contour->encloses_point($point) } @{$self->_contours_ex->[$_]} }
0 .. $#{ $self->_contours_ex };
} else {
# # look for an outer expolygon containing our point
$outer_polygon_idx = first { first { $_->encloses_point($point) } @{$self->_outer->[$_]} }
0 .. $#{ $self->_outer };
}
my $candidates = defined $outer_polygon_idx
? [ map @{$_->contour}, @{$self->_inner->[$outer_polygon_idx]} ]
: [ map @$_, map @$_, @{$self->_outer} ];
$candidates = [ map @$_, @{$self->_outer->[$outer_polygon_idx]} ]
if @$candidates == 0;
return $point->nearest_point($candidates);
exit if $self->internal;
}
}
@ -229,62 +134,188 @@ sub shortest_path {
my $self = shift;
my ($from, $to) = @_;
return Slic3r::Polyline->new($from, $to) if !@{$self->islands};
return Slic3r::Polyline->new($from, $to)
if !@{$self->_space->nodes};
# find nearest nodes
my $new_from = $self->find_node($from, $to);
my $new_to = $self->find_node($to, $from);
# create a temporary configuration space
my $space = $self->_space->clone;
my $root = "$new_from";
my $target = "$new_to";
my $edges = $self->_edges;
my %dist = map { $_ => INFINITY } keys %$edges;
$dist{$root} = 0;
my %prev = map { $_ => undef } keys %$edges;
my @unsolved = keys %$edges;
my %crossings = (); # node_idx => bool
# add from/to points to the temporary configuration space
my $node_from = $self->_add_point_to_space($from, $space);
my $node_to = $self->_add_point_to_space($to, $space);
while (@unsolved) {
# sort unsolved by distance from root
# using a sorting option that accounts for infinity
@unsolved = sort {
$dist{$a} eq INFINITY ? +1 :
$dist{$b} eq INFINITY ? -1 :
$dist{$a} <=> $dist{$b};
} @unsolved;
# compute shortest path
my $path = $space->shortest_path($node_from, $node_to);
if (!$path->is_valid) {
Slic3r::debugf "Failed to compute shortest path.\n";
return Slic3r::Polyline->new($from, $to);
}
if (0) {
require "Slic3r/SVG.pm";
Slic3r::SVG::output("path.svg",
no_arrows => 1,
expolygons => $self->islands,
lines => $space->get_lines,
red_points => [$from, $to],
red_polylines => [$path],
);
exit;
}
return $path;
}
# returns the index of the new node
sub _add_point_to_space {
my ($self, $point, $space) = @_;
my $n = $space->nodes_count;
$space->add_nodes($point);
# check whether we are inside an island or outside
my $inside = defined first { $self->islands->[$_]->encloses_point($point) } 0..$#{$self->islands};
# find candidates by checking visibility from $from to them
foreach my $idx (0..$#{$space->nodes}) {
my $line = Slic3r::Line->new($point, $space->nodes->[$idx]);
# if $point is inside an island, it is visible from $idx when island contains their line
# if $point is outside an island, it is visible from $idx when their line does not cross any island
if (
($inside && defined first { $_->encloses_line($line) } @{$self->_inner})
|| (!$inside && !@{Boost::Geometry::Utils::multi_polygon_multi_linestring_intersection(
[ map $_->pp, @{$self->islands} ],
[ $line->pp ],
)})
) {
# $n ($point) and $idx are visible
$space->add_edge($n, $idx, $line->length);
}
}
# if we found no visibility, retry with larger margins
if (!exists $space->edges->{$n} && $inside) {
foreach my $idx (0..$#{$space->nodes}) {
my $line = Slic3r::Line->new($point, $space->nodes->[$idx]);
if (defined first { $_->encloses_line($line) } @{$self->islands}) {
# $n ($point) and $idx are visible
$space->add_edge($n, $idx, $line->length);
}
}
}
warn "Temporary node is not visible from any other node"
if !exists $space->edges->{$n};
return $n;
}
package Slic3r::GCode::MotionPlanner::ConfigurationSpace;
use Moo;
has 'nodes' => (is => 'rw', default => sub { [] }); # [ Point, ... ]
has 'edges' => (is => 'rw', default => sub { {} }); # node_idx => { node_idx => distance, ... }
has '_infinity' => (is => 'rw');
sub clone {
my $self = shift;
return (ref $self)->new(
nodes => [ map $_->clone, @{$self->nodes} ],
edges => { map { $_ => { %{$self->edges->{$_}} } } keys %{$self->edges} },
_infinity => $self->_infinity,
);
}
sub nodes_count {
my $self = shift;
return scalar(@{ $self->nodes });
}
sub add_nodes {
my ($self, @nodes) = @_;
my $offset = $self->nodes_count;
push @{ $self->nodes }, @nodes;
return $offset;
}
sub add_edge {
my ($self, $a, $b, $dist) = @_;
$self->edges->{$a}{$b} = $self->edges->{$b}{$a} = $dist;
}
sub shortest_path {
my ($self, $node_from, $node_to) = @_;
my $edges = $self->edges;
my (%dist, %visited, %prev);
$dist{$_} = $self->_infinity for keys %$edges;
$dist{$node_from} = 0;
my @queue = ($node_from);
while (@queue) {
my $u = -1;
{
# find node in @queue with smallest distance in %dist and has not been visited
my $d = -1;
foreach my $n (@queue) {
next if $visited{$n};
if ($u == -1 || $dist{$n} < $d) {
$u = $n;
$d = $dist{$n};
}
}
}
last if $u == $node_to;
# we'll solve the closest node
last if $dist{$unsolved[0]} eq INFINITY;
my $n = shift @unsolved;
# remove $u from @queue
@queue = grep $_ != $u, @queue;
$visited{$u} = 1;
# stop search
last if $n eq $target;
# now, look at all the nodes connected to n
foreach my $n2 (keys %{$edges->{$n}}) {
# .. and find out if any of their estimated distances
# can be improved if we go through n
if ( ($dist{$n2} eq INFINITY) || ($dist{$n2} > ($dist{$n} + $edges->{$n}{$n2})) ) {
$dist{$n2} = $dist{$n} + $edges->{$n}{$n2};
$prev{$n2} = $n;
$crossings{$n} = 1 if $self->_crossing_edges->{$n}{$n2};
}
# loop through neighbors of $u
foreach my $v (keys %{ $edges->{$u} }) {
my $alt = $dist{$u} + $edges->{$u}{$v};
if ($alt < $dist{$v}) {
$dist{$v} = $alt;
$prev{$v} = $u;
if (!$visited{$v}) {
push @queue, $v;
}
}
}
}
my @points = ();
my $crossings = 0;
{
my $pointmap = $self->_pointmap;
my $u = $target;
while (defined $prev{$u}) {
unshift @points, $pointmap->{$u};
$crossings++ if $crossings{$u};
my $u = $node_to;
while (exists $prev{$u}) {
unshift @points, $self->nodes->[$u];
$u = $prev{$u};
}
unshift @points, $self->nodes->[$node_from];
}
$self->last_crossings($crossings);
return Slic3r::Polyline->new($from, $new_from, @points, $to); # @points already includes $new_to
return Slic3r::Polyline->new(@points);
}
# for debugging purposes
sub get_lines {
my $self = shift;
my @lines = ();
my %lines = ();
for my $i (keys %{$self->edges}) {
for my $j (keys %{$self->edges->{$i}}) {
my $line_id = join '_', sort $i, $j;
next if $lines{$line_id};
$lines{$line_id} = 1;
push @lines, Slic3r::Line->new(map $self->nodes->[$_], $i, $j);
}
}
return [@lines];
}
1;

2
lib/Slic3r/Print.pm
View file

@ -797,7 +797,7 @@ sub write_gcode {
}
$gcodegen->external_mp(Slic3r::GCode::MotionPlanner->new(
islands => union_ex([ map @$_, @islands ]),
no_internal => 1,
internal => 0,
));
}