--- /dev/null
+#!/usr/bin/perl -w
+
+use strict;
+use Math::Trig;
+use Math::Vector::Real;
+use IO::File;
+use Data::Dumper;
+use constant tau => pi*2;
+
+my $ellipse = 25 / 2;
+my $circle = 7 / 2;
+my $channelh = 3;
+my $channelw = 4;
+my $xscale = 35 / 25;
+my $N = 180; # around ellipse
+my $M = 80; # around each circle
+my @channeldistprops = (0, 1/3, 2/3);
+
+my $NMdiv = $ENV{'LEMONSTAND_COARSE'} || 1;
+
+$M /= $NMdiv;
+$N /= $NMdiv;
+
+print <<END;
+// -*- C -*-
+// *** AUTOGENERATED - DO NOT EDIT ***
+END
+
+print "torusyup = ", ($circle / sqrt(2)), ";\n";
+
+our @ellipse = map {
+ my $theta = tau * $_ / $N;
+ V( cos($theta) * $ellipse * $xscale, sin($theta) * $ellipse, 0 )
+} 0..($N-1);
+
+#print Dumper(\@ellipse);
+
+our @alongs = map {
+ my $i = $_;
+ $ellipse[ ($i+1) % $N ] - $ellipse[ ($i-1) % $N];
+} 0..($N-1);
+
+our @circles = map {
+ my $i = $_;
+ my $centre = $ellipse[$i];
+ my $axis = $alongs[$i]->versor();
+ my $rad0 = $axis x V(0,0,1);
+ my $rad1 = $rad0 x $axis;
+ [ map {
+ my $theta = tau * $_ / $M;
+ $centre + $circle * ($rad0 * cos($theta) + $rad1 * sin($theta));
+ } 0..($M-1) ];
+} 0..($N-1);
+
+sub scadvec ($) {
+ my ($v) = @_;
+ return "[ ".(join ", ", @$v)." ]"
+}
+
+sub torusy () {
+ print "module Torusy(){ polyhedron(points=[";
+ my $ptix = 0;
+ my @cirpt;
+ foreach my $i (0..$N-1) {
+ foreach my $j (0..$M-1) {
+ print "," if $ptix;
+ print "\n";
+ print " ",(scadvec $circles[$i][$j]);
+ $cirpt[$i][$j] = $ptix++;
+ }
+ }
+ print "\n ],\n";
+
+ print " faces=[";
+ foreach my $i (0..$N-1) {
+ my $i2 = ($i+1) % $N;
+ foreach my $j (0..$M-1) {
+ my $j2 = ($j+1) % $M;
+ print "," if $i || $j;
+ print "\n";
+ print " [ ", (join ", ",
+ $cirpt[ $i ][ $j ],
+ $cirpt[ $i ][ $j2 ],
+ $cirpt[ $i2 ][ $j ],
+ ), " ],";
+ print " [ ", (join ", ",
+ $cirpt[ $i ][ $j2 ],
+ $cirpt[ $i2 ][ $j2 ],
+ $cirpt[ $i2 ][ $j ],
+ ), " ]";
+ }
+ }
+ print "\n ]);\n}\n";
+}
+
+torusy();
+
+
+our @distances;
+push @distances, 0;
+foreach my $i (1..$N) {
+ my $dist = $distances[ $i-1 ];
+ $dist += abs($ellipse[$i % $N] - $ellipse[$i-1]);
+ $distances[$i] = $dist;
+}
+
+sub infodistprop ($) {
+ my ($distprop) = @_;
+ # returns
+ # ( $ellipse_centreline_point,
+ # $along_vector )
+ my $dist = $distprop * $distances[$N];
+ foreach my $i (0..$N-1) {
+ my $prorata =
+ ($dist - $distances[$i]) /
+ ($distances[$i+1] - $distances[$i]);
+ next unless 0 <= $prorata && $prorata <= 1;
+ print "// infodistprop $distprop => #$i=$ellipse[$i] $prorata $ellipse[$i+1]\n";
+ return (
+ (1-$prorata) * $ellipse[$i] + ($prorata) * $ellipse[$i+1],
+ $alongs[$i],
+ );
+ }
+ die "$distprop ?";
+}
+
+sub channels(){
+ print "module Channels(){\n";
+
+ foreach my $cdp (
+ (map { 0.5 * $_ } @channeldistprops),
+ (map { 0.5 * ($_+1) } @channeldistprops),
+ ) {
+ my ($ctr, $along) = infodistprop($cdp);
+ my $angle = atan2(-$along->[0], $along->[1]);
+ print " translate(",scadvec($ctr),")\n";
+ print " rotate([0,0,$angle*360/",tau,"])\n";
+ print " rotate([0,90,0])\n";
+ print " translate([0,0, -2*$circle])\n";
+ print " scale([1, $channelw/$channelh/2, 1])\n";
+ print " rotate([0,0,360/8/2])\n";
+ print " cylinder(r=$channelh, h=4*$circle, \$fn=8);\n";
+ }
+ print "}\n";
+}
+
+channels();
+
+while (<DATA>) { print };
+
+STDOUT->error and die $!;
+STDOUT->flush or die $!;
+
+__DATA__
+module Stand(){
+ difference(){
+ translate([0,0,torusyup])
+ Torusy();
+ Channels();
+ translate([-200,-200,-50])
+ cube([400,400,50]);
+ }
+}
+Stand();