<?php

set_time_limit(999);

$maxIterations = 100;

	// Randomize color
	$redColor = abs(255/(rand(1,4)));
	$greenColor = abs(255/(rand(1,4)));
	$blueColor = abs(255/(rand(1,4)));


// Allow the user to specify the image dimensions as the arguments "width" and "height" in the URL
$imgWidth = preg_replace('/[^0-9]/', '', $_GET['width']);
if(empty($imgWidth)){$imgWidth = "700";}
if($imgWidth > 4096){$imgWidth = 4096;}
$imgHeight = preg_replace('/[^0-9]/', '', $_GET['height']);
if(empty($imgHeight)){$imgHeight = "433";}
if($imgHeight > 2160){$imgHeight = 2160;}

$gd = imagecreatetruecolor($imgWidth, $imgHeight);
$black = imagecolorallocate($gd, 0, 0, 0);


// Randomize translation
$K_real = 0.233+((rand(1,8000)/71421));
$K_img = 0.505+((rand(1,9999)/142842));

$zoomFactor = (1-(rand(1,9999)/20000));

$minReal = -1.0*$zoomFactor;
$maxReal = 2.0*$zoomFactor;
$minImg = (-0.9-(rand(0,2)/10))*$zoomFactor;
$maxImg = $minImg + ($maxReal-$minReal)*($imgHeight/$imgWidth);


$c_real = $minReal + $x*($maxReal-$minReal)/($imgWidth-1);
$c_img = $minReal - $y*($maxImg-$minImg)/($imgHeight-1);

$Re_factor = ($maxReal-$minReal)/($imgWidth-1);
$Im_factor = ($maxImg-$minImg)/($imgHeight-1);

for($y=0;$y<$imgHeight;++$y){

	$c_img = $maxImg - $y*$Im_factor;

	for($x=0;$x<$imgWidth;++$x){

		$c_real = $minReal + $x*$Re_factor;

		$Z_real = $c_real;
		$Z_img = $c_img;

		$isInside = 1;
		for($i=0;$i<$maxIterations;++$i){

			$Z_real2 = $Z_real*$Z_real;
			$Z_img2 = $Z_img*$Z_img;
			if(($Z_real2 + $Z_img2)>4){

				$isInside = 0;
				break;
			}

			$Z_img = 2*$Z_real*$Z_img + $K_img;
			$Z_real = $Z_real2 - $Z_img2 + $K_real;
		}


		if($isInside){
			imagesetpixel($gd, $x, $y, $black);
		}
		else{
			$colorSet = imagecolorallocate($gd, ($i*$redColor), ($i*$greenColor), ($i*$blueColor));
			imagesetpixel($gd, $x, $y, $colorSet);
		}
	}
}

header('Content-Type: image/png');
imagepng($gd);

?>