distort-stl: wip, does not work because admesh

diff --git a/distort-stl b/distort-stl
new file mode 100755 (executable)
index 0000000..863c8d1
--- /dev/null
+++ b/distort-stl
@@ -0,0 +1,69 @@
+#!/usr/bin/perl -w
+#
+# usage:
+#   ./distort-stl <INPUT >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
+
+use strict;
+use autodie;
+
+sub shift_arg () {
+    die unless @ARGV;
+    scalar shift @ARGV;
+}
+
+sub pointmap_distortion {
+    my ($x,$y,$z) = @_;
+    my $radius = shift_arg;
+    my $r = $y + $radius;
+    my $theta = $x / $radius;
+    return ($r * cos($theta),
+           $r * sin($theta),
+           $z);
+}
+
+if (@ARGV && $ARGV[0] =~ m/^-/) {
+    die "no options supported\n";
+}
+
+my $admesh_pipe = '--write-ascii-stl 3<&0 4>&1 >/dev/null /dev/fd/4 /dev/fd/3';
+
+open I, "admesh $admesh_pipe |";
+open O, "| admesh --normal-values $admesh_pipe";
+
+our @saved_argv = @ARGV;
+
+while (<I>) {
+    if (s/^\s+vertex\s+//) {
+       my $lhs = $&;
+       s/\s+$//;
+       my @xyz = split /\s+/, $_;
+       while (@ARGV) {
+           my $op = shift_arg;
+           @xyz = &{ $::{"pointmap_$op"} }( @xyz );
+       }
+       @xyz = map { sprintf "%.18g", $_ } @xyz;
+       $_ = "$lhs@xyz\n";
+    }
+    print O;
+}
+
+<I>,<O> if 0; # suppresses Name "main::I" used only once
+
+close I;
+close O;