#!/usr/bin/perl -w
#
# usage:
# ./distort-stl OUTPUT DISTORTION [PARAMS...] ...
#
# DISTORTIONs:
#
# project-cylinder RADIUS
# projects the X-Z plane onto the cylinder of
# radius RADIUS with axis [0, 0, t]
# origin becomes [0, -RADIUS, 0]
# other planes of the input are projected onto smaller
# or larger cylinders accordingly
# probably a bad idea if
# object has any Y > RADIUS
# object has any |X| > tau / RADIUS
# technically, treats input as if it were
# polar-rectangular coords:
# Z' = Z; R' = Y + RADIUS; theta' = X / RADIUS
# and then converts back into cartesian
# honours fa but not fs or fn
#
# set-fa $FA
use strict;
use autodie;
use List::Util;
use POSIX;
use File::Temp ();
use Data::Dumper;
sub TAU () { M_PI * 2; }
our $fa = 10;
our $triangles;
our $output;
sub shift_arg () {
die unless @ARGV;
scalar shift @ARGV;
}
#no warnings qw(recursion);
sub subdivide_triangle ($$) {
my ($t, $fn) = @_;
#print STDERR 'SUBDIV', Dumper($t, $fn);
my @mids;
foreach my $ix (0..2) {
my $jx = ($ix+1) % 3;
my @midp;
foreach my $ci (0..2) {
push @midp, 0.5 * ($t->[$ix][$ci] + $t->[$jx][$ci]);
}
push @mids, \@midp;
}
foreach my $ix (0..2) {
#print STDERR 'SUBDIV IX ', $ix, "\n";
my $kx = ($ix+2) % 3;
$fn->([ $t->[$ix], $mids[$ix], $mids[$kx] ]);
}
#print STDERR 'SUBDIV MID\n';
$fn->(\@mids);
}
sub append_triangle ($) {
my ($t) = @_;
push @$output, $t;
}
#---------- project-cylinder ----------
our $project_cylinder_radius;
our $project_cylinder_max_d_theta;
sub project_cylinder_need_subdivide () {
foreach my $t (@$triangles) {
my @thetas = map { $_->[0] / $project_cylinder_radius } @$t;
foreach my $ix (0..2) {
if (abs($thetas[$ix] - $thetas[($ix+1)%3])
> $project_cylinder_max_d_theta) {
return 1;
}
}
}
return 0;
}
sub project_cylinder_tri {
my ($t) = @_;
#print STDERR 'PROJECT', Dumper($t);
my $radius = $project_cylinder_radius;
my @ot;
foreach my $p (@$t) {
my ($x,$y,$z) = @$p;
my $r = $radius - $y;
my $theta = $x / $radius;
push @ot, [ $r * sin($theta),
-$r * cos($theta),
$z ];
}
append_triangle \@ot;
}
sub op__project_cylinder () {
$project_cylinder_radius = shift_arg;
$project_cylinder_max_d_theta = $fa * TAU/360;
while (project_cylinder_need_subdivide()) {
$output = [];
foreach my $t (@$triangles) {
subdivide_triangle $t, \&append_triangle;
}
$triangles = $output;
}
$output = [];
foreach my $t (@$triangles) {
project_cylinder_tri $t;
}
$triangles = $output;
}
#---------- main program ----------
our $raw;
while (@ARGV && $ARGV[0] =~ m/^-/) {
$_ = shift @ARGV;
last if m/^--$/;
if (s/^--raw$//) {
$raw = 1;
} else {
die "$_ ?";
}
}
my $itmp;
my $otmp;
my $admesh_stdout = '--write-ascii-stl /dev/fd/3 3>&1 >/dev/null';
if ($raw) {
open I, "<& STDIN";
$otmp = *STDOUT;
} else {
$itmp = new File::Temp;
$otmp = new File::Temp;
system "cat >$itmp";
open I, "admesh $admesh_stdout $itmp |";
}
my $triangle;
while () {
s/^\s*//;
if (m/^outer\s+loop/) {
die if $triangle;
$triangle = [];
} elsif (s/^vertex\s+//) {
my $lhs = $&;
s/\s+$//;
my @xyz = split /\s+/, $_;
die unless $triangle;
push @$triangle, \@xyz;
} elsif (m/^endloop/) {
die unless @$triangle == 3;
push @$triangles, $triangle;
undef $triangle;
} elsif (m/^(?:solid|facet\s+normal|endfacet|endsolid)\s/) {
} else {
die "$_ ?";
}
}
close I;
if 0; # suppresses Name "main::I" used only once
while (@ARGV) {
my $op = shift_arg;
$op =~ y/-/_/;
&{ ${*::}{"op__$op"} };
}
select $otmp;
print "solid distort-stl\n";
foreach my $t (@$triangles) {
print " facet normal 0 0 0\n";
print " outer loop\n";
die unless @$t==3;
foreach my $p (@$t) {
die unless @$p==3;
print " vertex";
printf " %.18g", $_ foreach @$p;
print "\n";
}
print " endloop\n";
print " endfacet\n";
}
print "endsolid distort-stl\n";
flush $otmp;
if (!$raw) {
system "admesh --normal-values $admesh_stdout $otmp";
}