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perlin.js
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perlin.js
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// Ported from Stefan Gustavson's java implementation
// http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
// Read Stefan's excellent paper for details on how this code works.
//
// Sean McCullough [email protected]
// https://gist.github.com/304522
/**
* You can pass in a random number generator object if you like.
* It is assumed to have a random() method.
*/
var ClassicalNoise = exports.ClassicalNoise = function(r) { // Classic Perlin noise in 3D, for comparison
if (r == undefined) r = Math;
this.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]];
this.p = [];
for (var i=0; i<256; i++) {
this.p[i] = Math.floor(r.random()*256);
}
// To remove the need for index wrapping, double the permutation table length
this.perm = [];
for(var i=0; i<512; i++) {
this.perm[i]=this.p[i & 255];
}
};
ClassicalNoise.prototype.dot = function(g, x, y, z) {
return g[0]*x + g[1]*y + g[2]*z;
};
ClassicalNoise.prototype.mix = function(a, b, t) {
return (1.0-t)*a + t*b;
};
ClassicalNoise.prototype.fade = function(t) {
return t*t*t*(t*(t*6.0-15.0)+10.0);
};
// Classic Perlin noise, 3D version
ClassicalNoise.prototype.noise = function(x, y, z) {
// Find unit grid cell containing point
var X = Math.floor(x);
var Y = Math.floor(y);
var Z = Math.floor(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 = this.perm[X+this.perm[Y+this.perm[Z]]] % 12;
var gi001 = this.perm[X+this.perm[Y+this.perm[Z+1]]] % 12;
var gi010 = this.perm[X+this.perm[Y+1+this.perm[Z]]] % 12;
var gi011 = this.perm[X+this.perm[Y+1+this.perm[Z+1]]] % 12;
var gi100 = this.perm[X+1+this.perm[Y+this.perm[Z]]] % 12;
var gi101 = this.perm[X+1+this.perm[Y+this.perm[Z+1]]] % 12;
var gi110 = this.perm[X+1+this.perm[Y+1+this.perm[Z]]] % 12;
var gi111 = this.perm[X+1+this.perm[Y+1+this.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= this.dot(this.grad3[gi000], x, y, z);
var n100= this.dot(this.grad3[gi100], x-1, y, z);
var n010= this.dot(this.grad3[gi010], x, y-1, z);
var n110= this.dot(this.grad3[gi110], x-1, y-1, z);
var n001= this.dot(this.grad3[gi001], x, y, z-1);
var n101= this.dot(this.grad3[gi101], x-1, y, z-1);
var n011= this.dot(this.grad3[gi011], x, y-1, z-1);
var n111= this.dot(this.grad3[gi111], x-1, y-1, z-1);
// Compute the fade curve value for each of x, y, z
var u = this.fade(x);
var v = this.fade(y);
var w = this.fade(z);
// Interpolate along x the contributions from each of the corners
var nx00 = this.mix(n000, n100, u);
var nx01 = this.mix(n001, n101, u);
var nx10 = this.mix(n010, n110, u);
var nx11 = this.mix(n011, n111, u);
// Interpolate the four results along y
var nxy0 = this.mix(nx00, nx10, v);
var nxy1 = this.mix(nx01, nx11, v);
// Interpolate the two last results along z
var nxyz = this.mix(nxy0, nxy1, w);
return nxyz;
};