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sl2/: standalone slicer (WIP)

sfc/slicer.py has troubles with artefacts. It seems that we can do much
better by avoiding the high-level operations and doing all the slicing
"manually".
This commit is contained in:
Werner Almesberger 2015-09-29 10:51:08 -03:00
parent 5c6a81033f
commit 6800f025c1
2 changed files with 131 additions and 0 deletions

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sl2/README Normal file
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Yet another slicer. This one picks up the idea from sfc/slicer.py but
implements it without using FreeCAD. The FreeCAD-based solution turned
out to produce weird artefacts for some reason, e.g., open paths that
were then falsely closed and yielded bogus toolpaths.
This slicer uses very strict conditions for horizontality: all the
points of a horizontal facet must have identical Z coordinates. It
also implicitly ensures that all paths are closed.

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sl2/slicer.pl Executable file
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#!/usr/bin/perl
#
# slicer.pl - Standalone STL to Gnuplot slicer
#
# Written 2015 by Werner Almesberger
# Copyright 2015 by Werner Almesberger
#
# This program//library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
$epsilon = 0.0001;
$flip = 1;
$v_n = 0;
$e_n = 0;
while (<>) {
if (/\bfacet/) {
undef @f;
next;
}
if (/endfacet/) {
if ($f[2] == $f[5] && $f[2] == $f[8]) {
$z_level{$f[2]} = 1;
} else {
push(@m, [ @f ]);
}
next;
}
if (/vertex\s+/) {
my @tmp = split(/\s+/, $');
if ($flip) {
push(@f, -$tmp[0], $tmp[1], -$tmp[2]);
} else {
push(@f, @tmp);
}
next;
}
}
sub cut
{
local ($z, $a, $b, @f) = @_;
if ($f[$a + 2] < $z &&$f[$b + 2] > $z) {
my $dx = $f[$b] - $f[$a];
my $dy = $f[$b + 1] - $f[$a + 1];
my $dz = $f[$b + 2] - $f[$a + 2];
my $f = ($z - $f[$a + 2]) / $dz;
return [ $dx * $f + $f[$a], $dy * $f + $f[$a + 1] ];
}
if ($f[$a + 2] > $z &&$f[$b + 2] < $z) {
return &cut($z, $b, $a, @f);
}
return ();
}
sub remove
{
local ($a, $b) = @_;
#print STDERR "\tremove $b from $a (", join(",", @{ $next{$a} }), "\n";
my @tmp = grep($_ ne $b, @{ $next{$a} });
if ($#tmp == -1) {
delete $next{$a};
} else {
$next{$a} = [ @tmp ];
}
}
for $level (sort keys %z_level) {
my $z = $level + $epsilon;
# print STDERR "level = $level\n";
undef %next;
for (@m) {
my @f = @{ $_ };
my @p = &cut($z, 0, 3, @f);
push(@p, &cut($z, 0, 6, @f));
push(@p, &cut($z, 3, 6, @f));
next if $#p < 1;
die "BAD $#p" if $#p > 1;
my $a = "$p[0][0] $p[0][1]";
my $b = "$p[1][0] $p[1][1]";
push(@{ $next{$a} }, $b);
push(@{ $next{$b} }, $a);
# print STDERR "$z: ($a) to ($b)\n";
}
while (1) {
my @k = keys %next;
last if $#k == -1;
my $p0 = $k[0];
$p = $p0;
while (1) {
my $next = $next{$p}[0];
print "$p $z\n";
# print STDERR "at $p\n";
# print STDERR "\tnext $next\n";
die "open path" unless defined $next;
&remove($p, $next);
&remove($next, $p);
last if $p0 eq $next;
$p = $next;
}
print "$p0 $z\n";
print "\n";
}
}