Mandelbrot Generation Class

<?php

// mandelbrot generation class v1.0
// (c) copyright 2006 positive blue <[email protected]>
// some rights reserved

class Mandelbrot
{
	// thats where all step coordinates are stored
	public $coArray = array();
	public $maxiter = 256;
	
	// picture width and height
	public $width = 800;
	public $height = 600;
	
	// palette and colors
	public $palette = array();
	public $colors = 64; // number of colors
	public $set_colors = false;
	
	// steps config
	private $steps;
	
	// this function loads coordinates from the file
	public function loadConfigFile($filename)
	{
		if (file_exists($filename))
		{
			$co = file($filename);
			
			// loop through each line and add coordinates
			foreach ($co as $n => $line)
			{
				// explode
				if (!empty($line))
					$this->coArray[] = explode(" ", trim($line));
			}
			
			$this->steps = count($this->coArray);
			return $this->steps;
		} else {
			// could not load file
			return false;
		}
	}
	
	// prepare image object
	private function initImage()
	{
		return imagecreatetruecolor($this->width, $this->height);
	}
	
	// this allocates palette in image object
	private function createPalette($img)
	{
		for ($i = 0; $i != $this->colors; $i++)
		{
			if (is_array($this->set_colors))
			{
				eval('$c1 = $i' . $this->set_colors[0] . ';');
				eval('$c2 = $i' . $this->set_colors[1] . ';');
				eval('$c3 = $i' . $this->set_colors[2] . ';');
			} else {
				$c1 = $i * 5;
				$c2 = $i + 3;
				$c3 = $i + 6;
			}
			
			$c1 = $c1 > 255 ? 255 : $c1; $c1 = $c1 < 1 ? 1 : $c1;
			$c2 = $c2 > 255 ? 255 : $c2; $c2 = $c2 < 1 ? 1 : $c2;
			$c3 = $c3 > 255 ? 255 : $c3; $c3 = $c3 < 1 ? 1 : $c3;
			
			$this->palette[$i] = imagecolorallocate($img, round($c1), round($c2), round($c3));
			$this->palette[($this->maxiter / 2 + 1) - $i] = $this->palette[$i];
		}
		return $palette;
	}
	
	// this function draws a step
	public function doStep($pic, $step = 0)
	{
		// set our vars
		$xmin = (float) $this->coArray[$step][0];
		$xmax = (float) $this->coArray[$step][1];
		$ymin = (float) $this->coArray[$step][2];
		$ymax = (float) $this->coArray[$step][3];
		
		$dx = ($xmax - $xmin) / $this->width;
 		$dy = ($ymax - $ymin) / $this->height;
		
		$py = 0;
		$y = $ymin;
		
		while ($py < $this->height)
		{
			$px = 0;
			$x = $xmin;
			$py++;
			
			while ($px < $this->width)
			{
				$px++;
				
				$fx = 0;
				$fy = 0;
				$m = 0;
				
				while ((($fx * $fx + $fy * $fy) < 4) && ($m < $this->maxiter))
				{
					$old_x = $fx;
					$fx = ($fx * $fx) - ($fy * $fy) + $x;
					$fy = 2 * $old_x * $fy + $y;
					$m++;
				}
				
				$color = ($m == $this->maxiter + 1) ? 0 : $this->palette[$m % ($this->maxiter / 2 + 1)];
				
				imagesetpixel($pic, $px, $py, $color);
				
				$x += $dx;
			}
			
			$y += $dy;
		}
	}
	
	public function run($output_dir = '.')
	{
		for($i = 0; $i < count($this->coArray); $i++)
		{
			$img = $this->initImage();
			$this->createPalette(& $img);
			$this->doStep(& $img, $i);
			
			imagepng($img, $output_dir . '/img' . ($i + 1) . ".png");
		}
	}
}

set_time_limit(3600);
$m = new Mandelbrot();
$m->width = 320;
$m->height = 240;
$m->maxiter = 64;
$m->set_colors = array('*2', '*2', '*3');
$m->colors = 120;

//$m->loadConfigFile("input.txt");
$m->coArray = array(
	0	=>	array(-1, 1, -1, 1)
);

$m->run('output');

?>