PHP Perlin Noise Class

perlin.php

//This is a port of Ken Perlin's "Improved Noise"
//     http://mrl.nyu.edu/~perlin/noise/

// Originally from http://therandomuniverse.blogspot.com/2007/01/perlin-noise-your-new-best-friend.html
// but the site appears to be down, so here is a mirror of it

class Perlin {
	
	var $p, $permutation, $seed;
	var $_default_size = 64;
	
	function Perlin ($seed=NULL) {
		
		//Initialize the permutation array.
		$this->p = array();
		$this->permutation = array( 151,160,137,91,90,15,
		131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
		190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
		88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
		77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
		102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
		135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
		5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
		223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
		129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
		251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
		49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
		138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180
		);
		
		//Populate it
		for ($i=0; $i < 256 ; $i++) {
			$this->p[256+$i] = $this->p[$i] = $this->permutation[$i]; 
		}
		
		//And set the seed
		if ($seed === NULL) $this->seed = time();
		else $this->seed = $seed;
	}
	
	function noise($x,$y,$z,$size=NULL) {
		
		if ($size == NULL) $size = $this->_default_size;
		
		//Set the initial value and initial size
		$value = 0.0; $initialSize = $size;
		
		//Add finer and finer hues of smoothed noise together
		while($size >= 1) {
	
			$value += $this->smoothNoise($x / $size, $y / $size, $z / $size) * $size;
			$size /= 2.0;

		}
		
		//Return the result over the initial size
		return $value / $initialSize;
	
	}
	
	//This function determines what cube the point passed resides in
	//and determines its value.
	function smoothNoise($x, $y, $z) {
		
		//Offset each coordinate by the seed value
		$x+=$this->seed; $y+=$this->seed; $z+=$this->seed;
		
		$orig_x = $x;
		$orig_y = $y;
		$orig_z = $z;
		
		$X1 = (int)floor($x) & 255;                  // FIND UNIT CUBE THAT
		$Y1 = (int)floor($y) & 255;                  // CONTAINS POINT.
		$Z1 = (int)floor($z) & 255;
		$x -= floor($x);                                // FIND RELATIVE X,Y,Z
		$y -= floor($y);                                // OF POINT IN CUBE.
		$z -= floor($z);
		$u = $this->fade($x);                                // COMPUTE FADE CURVES
		$v = $this->fade($y);                                // FOR EACH OF X,Y,Z.
		$w = $this->fade($z);
		
		$A  = $this->p[$X1]+$Y1;
		$AA = $this->p[$A]+$Z1;
		$AB = $this->p[$A+1]+$Z1;      // HASH COORDINATES OF
		$B  = $this->p[$X1+1]+$Y1;
		$BA = $this->p[$B]+$Z1;
		$BB = $this->p[$B+1]+$Z1;      // THE 8 CUBE CORNERS,
		
		//Interpolate between the 8 points determined
		$result = $this->lerp($w, $this->lerp($v, $this->lerp($u, $this->grad($this->p[$AA  ], $x  , $y  , $z   ),  // AND ADD
																  $this->grad($this->p[$BA  ], $x-1, $y  , $z   )), // BLENDED
												  $this->lerp($u, $this->grad($this->p[$AB  ], $x  , $y-1, $z   ),  // RESULTS
																  $this->grad($this->p[$BB  ], $x-1, $y-1, $z   ))),// FROM  8
								  $this->lerp($v, $this->lerp($u, $this->grad($this->p[$AA+1], $x  , $y  , $z-1 ),  // CORNERS
																  $this->grad($this->p[$BA+1], $x-1, $y  , $z-1 )), // OF CUBE
												  $this->lerp($u, $this->grad($this->p[$AB+1], $x  , $y-1, $z-1 ),
																  $this->grad($this->p[$BB+1], $x-1, $y-1, $z-1 ))));
		
		return $result;
	}
	
	function fade($t) { 
		return $t * $t * $t * ( ( $t * ( ($t * 6) - 15) ) + 10);
	}
	
	function lerp($t, $a, $b) { 
		//Make a weighted interpolaton between points
		return $a + $t * ($b - $a); 
	}
	
	function grad($hash, $x, $y, $z) {
		$h = $hash & 15;                      // CONVERT LO 4 BITS OF HASH CODE
		$u = $h<8 ? $x : $y;                 // INTO 12 GRADIENT DIRECTIONS.
		$v = $h<4 ? $y : ($h==12||$h==14 ? $x : $z);
		
		return (($h&1) == 0 ? $u : -$u) + (($h&2) == 0 ? $v : -$v);
	}
	
	//This function I've added. It creates one dimension of noise.
	function random1D($x) {
   	
		if ($size === NULL) $size = $this->_default_size;
		
		$x += $this->seed;
		
		$value = 0.0; $initialSize = $size = 3;
		
		while($size >= 1){
			$value += $this->smoothNoise($x*3 / $size, 100 / $size, 100 / $size);
			$size--;
		}
		
		if ($value < -1) $value = -1;
		if ($value > 1) $value = 1;
		
		return $value;
   
   }
   
   //Same as random1D() only for 2 dimensions.
   function random2D($x,$y) {
   	
		if ($size === NULL) $size = $this->_default_size;
		
		$x += $this->seed;
		$y += $this->seed;
		
		$value = 0.0; $initialSize = $size = 3;
		
		while($size >= 1) {
			$value += $this->smoothNoise($x*3 / $size, $y*3 / $size, 100 / $size);
			$size--;
		}
		
		if ($value < -1) $value = -1;
		if ($value > 1) $value = 1;
		
		return $value;
   
   }
}

/*
//This is a small test snippet that will output an example with DIV tags.
//Feel free to fiddle with it.
$bob = new Perlin(2000);

$size = 1;
$smooth = 42;
$gridsize = 125;

for($y=0; $y<$gridsize; $y+=1) {
	for($x=0; $x<$gridsize; $x+=1) {
		$num = $bob->noise($x,$y,0,$smooth);
		
		$raw = ($num/2)+.5;
		//if ($num == 0) $raw = 0;
		//else $raw = 1/abs( $num );
		
		//$raw = pow((5*$raw)-4,3)+.5;
		//$raw = 1-pow(50 * ($raw - 1), 2);
		
		//if ($raw > .9) $raw = 1;
		//else $raw = 0;
		if ($raw < 0) $raw = 0;
		
		$num = dechex( $raw*255 );
		
		if (strlen($num) < 2) $num = "0".$num;
		echo '
';
	}
}
//*/

/*
$bob = new Perlin(1);

$place = 0;

//for ($i=0; $i<100000; $i+=100) {
for ($i=0; $i<1000; $i++) {
	$num = round(($bob->random1D($i)/2)+.5,2);
	echo $num.'
';
	echo '';
	$place++;
}
//*/