use GD;
use strict;

my($width) = 500;
my($height) = 200;

my($image) = new GD::Image($width, $height);

my($white) = $image->colorAllocate(255, 255, 255);
my($black) = $image->colorAllocate(0, 0, 0);       
my($red) = $image->colorAllocate(255, 0, 0);

$image->transparent($white);
$image->interlaced('true');

my($center) = $height/2;
my($grid) = 30;
my($checkline) = 3;

#foreach (1..$width/$grid) {
#	$image->line($_*$grid, 0, $_*$grid, $height, $black);
#	$image->line(0, $_*$grid, $width, $_*$grid, $black);
#}

#$image->line($center, 0, $center, $height, $red);
#$image->line(0, $center, $width, $center, $red);

#&drawgraph;

my($start) = {};
my($end) = {};

$start->{'x'} = 0;
$start->{'y'} = $height-1;

$end->{'x'} = $width-1;
$end->{'y'} = $height-1;

my(@point) = &koch($start, $end);

for (my($i) = 0; $i+1 < @point; $i++) {
	$image->line($point[$i]{'x'}, $point[$i]{'y'}, $point[$i+1]{'x'}, $point[$i+1]{'y'}, $black);
}

open(OUT, "> graph.png");
binmode(OUT);
print OUT $image->png;
close(OUT);

#sub forsize {
#	$elements = @_;
#	@tmp = sort({$a <=> $b} @_);
#	$max = $tmp[0];
#	$min = $tmp[@tmp];
#
#	$w = $elements * 50;
#	$h = 100;
#	return ($w, $h);
#}

# ‹éŒ`”g
sub square {
	my($x) = shift;
	my($r) = 0;

	$x *= 1/2;
	foreach (1..30) {
		$_ = $_*2-1;

		$r += sin($x*$_)/$_;
	}
	$r *= 5;

	return $r;
}

sub drawgraph {
	my(%prev);

	for (my($i) = 0; $i < $width; $i++) {
		my($x) = ($i - $center) / $grid;
		my($y);

		$y = &square($x);
#		$y = $x**$x;

		my($w) = $center + $x * $grid;
		my($h) = $center - $y * $grid;

		if (!%prev) {
			$prev{'w'} = $w;
			$prev{'h'} = $h;
		}

		$image->line($prev{'w'}, $prev{'h'}, $w, $h, $black);

		$prev{'w'} = $w;
		$prev{'h'} = $h;
	}
}

sub koch {
	my($start) = shift;
	my($end) = shift;
	my(@pt);

	if (&dist($start, $end) <= 1) {
		push(@pt, $start);
		push(@pt, $start);
		return @pt;
	}

	my($middle_left) = &pointing($start, $end, 3, 1);
	my($middle_right) = &pointing($start, $end, 3, 2);
	my($top) = &rotate($middle_left, $middle_right);

	push(@pt, &koch($start, $middle_left));
	push(@pt, &koch($middle_left, $top));
	push(@pt, &koch($top, $middle_right));
	push(@pt, &koch($middle_right, $end));
	push(@pt, $end);
	
	return @pt;
}

sub pointing {
	my($st) = shift;
	my($en) = shift;
	my($div) = shift;
	my($rate) = shift;
	my($pt) = {};

	$pt->{'x'} = (($div-$rate)*$st->{'x'} + $rate*$en->{'x'}) / $div;
	$pt->{'y'} = (($div-$rate)*$st->{'y'} + $rate*$en->{'y'}) / $div;

	return $pt;
}

sub dist {
	my($st) = shift;
	my($en) = shift;

	return sqrt(abs($st->{'x'}-$en->{'x'})**2 + abs($en->{'y'}-$en->{'y'})**2);
}

sub rotate {
	my($PI) = 3.1415;
	my($center) = shift;
	my($target) = shift;
	my($pt) = {};

	$pt->{'x'} = $center->{'x'} + cos(-$PI/3)*($target->{'x'}-$center->{'x'}) - sin(-$PI/3)*($target->{'y'}-$center->{'y'});
	$pt->{'y'} = $center->{'y'} + sin(-$PI/3)*($target->{'x'}-$center->{'x'}) + cos(-$PI/3)*($target->{'y'}-$center->{'y'});

	return $pt;
}

sub drawpoint {
	my($pt) = shift;

	$image->setPixel($pt->{'x'}, $pt->{'y'}, $black);
}