Improved noise by Ken Perlin, optimised for JS

Perlin.js

// Improved noise
// JS version written by Ken Perlin
// http://mrl.nyu.edu/~perlin
// Modified by Omer Shapira
// http://omershapira.com


var perlin = (function() {
    var p = (function() {
      // Perlin's artisanal shuffle
        var p_bootstrap = [ 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 ];
        return new Uint8Array(p_bootstrap.concat(p_bootstrap));
        }
    )();

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

    var lerp = function(t, a, b) { return a + t * (b - a); };

    var grad = function(hash, x, y, z) {
      var h = hash & 15;                      // CONVERT LO 4 BITS OF HASH CODE
      var 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)
    };

    var noisefunc = function(x, y, z) {
      var X = Math.floor(x) & 255, Y = Math.floor(y) & 255, Z = Math.floor(z) & 255;
      x -= Math.floor(x); y -= Math.floor(y); z -= Math.floor(z);
      var u = fade(x), v = fade(y), w = fade(z);
      var A = p[X] + Y, AA = p[A]+Z, AB = p[A+1]+Z,      // HASH COORDINATES OF
          B = p[X+1]+Y, BA = p[B]+Z, BB = p[B+1]+Z;      // THE 8 CUBE CORNERS,
      return lerp(w, lerp(v, lerp(u, grad(p[AA  ], x  , y  , z   ),  // AND ADD
                                     grad(p[BA  ], x-1, y  , z   )), // BLENDED
                             lerp(u, grad(p[AB  ], x  , y-1, z   ),  // RESULTS
                                     grad(p[BB  ], x-1, y-1, z   ))),// FROM  8
                     lerp(v, lerp(u, grad(p[AA+1], x  , y  , z-1 ),  // CORNERS
                                     grad(p[BA+1], x-1, y  , z-1 )), // OF CUBE
                     lerp(u, grad(p[AB+1], x  , y-1, z-1 ),
                         grad(p[BB+1], x-1, y-1, z-1 ))));
    };
    return noisefunc;
})();

var perlin_octaves = function(){
    if (arguments.length){
        var args = Array.prototype.slice.call(arguments, 0);
        var funcs = args.map(
                function(n, i){ 
                return function(x,y,z) { 
                    var pow2 = (1 << i) * 0.05; //FIXME: Maybe shouldn't be power 2?
                    return n * noise(pow2 * x, pow2 * y, pow2 * z); }
                    } 
            );
        return function(x,y,z){ 
            return funcs.reduce(function(prev, f){
                return f(x,y,z) + prev;
            }, 0);
        }
    } else { return noise; }  
};

var perlin_falloff = function(octaves, falloff){
    var a = Array(octaves);
    var f = 1;
    for (var i = 0; i < a.length; i++) {
        a[i] = f;
        f *= falloff;
    };
    return perlin_octaves.apply(this, a);
}