classic-noise.js

define(['app'], function (app) {
    'use strict';

    // Classic Perlin noise in 3D, for comparison

    var grad3 = [[1,1,0], [-1,1,0], [1,-1,0], [-1,-1,0],
    [1,0,1], [-1,0,1], [1,0,-1], [-1,0,-1],
    [0,1,1], [0,-1,1], [0,1,-1], [0,-1,-1]];

    var p = [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];

    var perm = new Array(512);
    for (var i = 0; i < 512; i++) {
        perm[i] = p[i & 255];
    }

    // This method is a *lot* faster than using (int)Math.floor(x)
    function fastfloor (x) {
        //return x > 0 ? (int)x : (int)x-1;
        return Math.floor(x);
    }

    function dot(g, x, y, z) {
        return g[0]*x + g[1]*y + g[2]*z;
    }

    function mix(a, b, t) {
        return (1-t)*a + t*b;
    }

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

    var ClassicNoise = function () {
    };

    ClassicNoise.prototype = {
        noise: function (x, y, z) {
            // Find unit grid cell containing point
            var X = fastfloor(x);
            var Y = fastfloor(y);
            var Z = fastfloor(z);

            // Get relative xyz coordinates of point within that cell
            x = x - X;
            y = y - Y;
            z = z - Z;

            // Wrap the integer cells at 255 (smaller integer period can be introduced here)
            X = X & 255;
            Y = Y & 255;
            Z = Z & 255;

            // Calculate a set of eight hashed gradient indices
            var gi000 = perm[X+perm[Y+perm[Z]]] % 12;
            var gi001 = perm[X+perm[Y+perm[Z+1]]] % 12;
            var gi010 = perm[X+perm[Y+1+perm[Z]]] % 12;
            var gi011 = perm[X+perm[Y+1+perm[Z+1]]] % 12;
            var gi100 = perm[X+1+perm[Y+perm[Z]]] % 12;
            var gi101 = perm[X+1+perm[Y+perm[Z+1]]] % 12;
            var gi110 = perm[X+1+perm[Y+1+perm[Z]]] % 12;
            var gi111 = perm[X+1+perm[Y+1+perm[Z+1]]] % 12;

            // The gradients of each corner are now:
            // g000 = grad3[gi000];
            // g001 = grad3[gi001];
            // g010 = grad3[gi010];
            // g011 = grad3[gi011];
            // g100 = grad3[gi100];
            // g101 = grad3[gi101];
            // g110 = grad3[gi110];
            // g111 = grad3[gi111];

            // Calculate noise contributions from each of the eight corners
            var n000= dot(grad3[gi000], x, y, z);
            var n100= dot(grad3[gi100], x-1, y, z);
            var n010= dot(grad3[gi010], x, y-1, z);
            var n110= dot(grad3[gi110], x-1, y-1, z);
            var n001= dot(grad3[gi001], x, y, z-1);
            var n101= dot(grad3[gi101], x-1, y, z-1);
            var n011= dot(grad3[gi011], x, y-1, z-1);
            var n111= dot(grad3[gi111], x-1, y-1, z-1);

            // Compute the fade curve value for each of x, y, z
            var u = fade(x);
            var v = fade(y);
            var w = fade(z);

            // Interpolate along x the contributions from each of the corners
            var nx00 = mix(n000, n100, u);
            var nx01 = mix(n001, n101, u);
            var nx10 = mix(n010, n110, u);
            var nx11 = mix(n011, n111, u);

            // Interpolate the four results along y
            var nxy0 = mix(nx00, nx10, v);
            var nxy1 = mix(nx01, nx11, v);

            // Interpolate the two last results along z
            var nxyz = mix(nxy0, nxy1, w);

            return nxyz;
        }
    };

    return ClassicNoise;
});