#!/bin/perl
use Math::Trig;
# SVG Gosper curve generator by Blotwell
# Released under GFDL

my $x=500, $y=2500, $a=90;
my $ln=100;

printf <<HEREDOC, $x,$y;
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg" version="1.1"
	width="640px" height="640px"
>
<polyline
	stroke="red"
	stroke-width="10"
	fill="none"
	transform="scale(0.1)"
	points="%i,%i
HEREDOC

rg(4);
print <<HEREDOC;
"/>
</svg>
HEREDOC

sub p {printf " %i,%i",$x,$y;}
sub fd {my $n=shift; $x+=$n*cos(deg2rad($a)); $y-=$n*sin(deg2rad($a)); p();}
sub tl {$a+=shift;}
sub rt {$a-=shift;}

sub gl {
	my $st=-1+shift;
	if ($st<0) {
		fd($ln);
		return
	}

	tl(60);  rg($st);
	rt(60);  gl($st); gl($st);
	rt(120); gl($st);
	rt(60);  rg($st);
	tl(120); rg($st);
	tl(60);  gl($st);
}

sub rg {
	my $st=-1+shift;
	if ($st<0) {
		fd($ln);
		return;
	}

	rg($st);
	rt(60);  gl($st);
	rt(120); gl($st);
	tl(60);  rg($st);
	tl(120); rg($st); rg($st);
	tl(60);  gl($st);
	rt(60);
}