#!/usr/bin/perl -w
#sierpinski1.pl
#Created 22 Jan 2007 by John T. Wodder II
#This code is in the public domain.
use strict;

my $depth = shift || 7;
my $size = shift || 100;
my $file = shift || 'sierpinski.eps';
my $height = $size / 2 * sqrt 3;
my @tris = ([[0, 0], [$size/2, $height], [$size, 0]]);

open(FILE, '>', $file);
select FILE;
print <<EOT;
%!PS-Adobe-3.0 EPSF-3.0
%%BoundingBox: 0 0 $size $height
% $0, depth: $depth, size: $size
newpath 0 0 moveto
$size 2 div dup 3 sqrt mul rlineto
currentpoint -1 mul rlineto
closepath fill
1 setgray\n
EOT

for (1..$depth) {
 my $max = @tris;
 for (1..$max) {
  my $curr = shift @tris;
  my @p0 = (($curr->[1][0]+$curr->[2][0])/2, ($curr->[1][1]+$curr->[2][1])/2);
  my @p1 = (($curr->[0][0]+$curr->[2][0])/2, ($curr->[0][1]+$curr->[2][1])/2);
  my @p2 = (($curr->[1][0]+$curr->[0][0])/2, ($curr->[1][1]+$curr->[0][1])/2);
  print "newpath $p0[0] $p0[1] moveto ", $p1[0]-$p0[0], " ", $p1[1]-$p0[1], " rlineto ", $p2[0]-$p1[0], " ", $p2[1]-$p1[1], " rlineto closepath fill\n";
  push @tris, ([[@{$curr->[0]}], [@p1], [@p2]], [[@{$curr->[1]}], [@p0], [@p2]], [[@{$curr->[2]}], [@p0], [@p1]]);
 }
}
print "showpage";
close(FILE);