+ if ($wireframe_p) {
+
+ # Convert faces to lines.
+ # Don't duplicate shared edges.
+
+ foreach my $layer (keys %triangles) {
+ my %dups;
+ my @triangles = @{$triangles{$layer}};
+ while (@triangles) {
+ my $x1 = shift @triangles; # 0
+ my $y1 = shift @triangles; # 1
+ my $z1 = shift @triangles; # 2
+ my $x2 = shift @triangles; # 3
+ my $y2 = shift @triangles; # 4
+ my $z2 = shift @triangles; # 5
+ my $x3 = shift @triangles; # 6
+ my $y3 = shift @triangles; # 7
+ my $z3 = shift @triangles; # 8
+
+ my $p = sub(@) {
+ my ($x1, $y1, $z1, $x2, $y2, $z2) = @_;
+ my $key1 = "$x1, $y1, $z1, $x2, $y2, $z2";
+ my $key2 = "$x2, $y2, $z2, $x1, $y1, $z1";
+ my $dup = $dups{$key1} || $dups{$key2};
+ $dups{$key1} = 1;
+ $dups{$key2} = 1;
+ push @{$lines{$layer}}, @_ unless $dup;
+ }
+ ;
+ $p->($x1, $y1, $z1, $x2, $y2, $z2);
+ $p->($x2, $y2, $z2, $x3, $y3, $z3);
+ $p->($x3, $y3, $z3, $x1, $y1, $z1);
+ }