noise3d/lib/noise/perlin.js

3D Noise

var fade = function(x) {
	return x * x * x * (x * (x * 6 - 15) + 10);
};

var grad = function(hash, x, y, z) {
	var h = hash & 15;
	var u = h < 8 ? x : y;
	var v = h < 4 ? y : h == 12 || h == 14 ? x : z;
	return ((h&1) ? -u : u) + ((h&2) ? -v : v);
};

var perlin = function(params) {
	
	if (typeof params != "object")
		throw new TypeError("params is not an object");
	if (typeof params.interpolation != "function")
		throw new TypeError("params.interpolation is not a function");
	if (!Array.isArray(params.permutation))
		throw new TypeError("params.permutation is not an array");
	if (params.permutation.length != 256)
		throw new Error("params.permutation must have 256 items");
	
	var irp = params.interpolation;
	var p = params.permutation.slice(0);
		
	for (var i = 0; i < 256; i++)
		p[256+i] = p[i];
	
	return function(x, y, z) {
		var fx = Math.floor(x);
		var fy = Math.floor(y);
		var fz = Math.floor(z);
		
		var X = fx & 255;
		var Y = fy & 255;
		var Z = fz & 255;
			
		x -= fx;
		y -= fy;
		z -= fz;
		
		var u = fade(x);
		var v = fade(y);
		var w = fade(z);
			
		var A  = p[X] + Y;
		var AA = p[A] + Z;
		var AB = p[A+1]	+ Z;
		var B  = p[X+1] + Y;
		var BA = p[B] + Z;
		var BB = p[B+1] + Z;
			
		return irp(
			irp(	irp(	grad(p[AA  ], x  , y  , z   ),
							grad(p[BA  ], x-1, y  , z   ),
							u),
					irp(	grad(p[AB  ], x  , y-1, z   ),  
							grad(p[BB  ], x-1, y-1, z   ),
							u),
					v),
			irp(	irp(	grad(p[AA+1], x  , y  , z-1 ),  
							grad(p[BA+1], x-1, y  , z-1 ),
							u), 
					irp(	grad(p[AB+1], x  , y-1, z-1 ),
							grad(p[BB+1], x-1, y-1, z-1 ),
							u),
					v),
			w);
	};
};

module.exports = perlin;