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noise.js
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noise.js
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/**
* Simplex and Perlin noise.
*
* Copied with small edits from https://github.com/josephg/noisejs which is
* public domain. Originally by Stefan Gustavson ([email protected]) with
* optimizations by Peter Eastman ([email protected]) and converted
* to JavaScript by Joseph Gentle.
*/
(function(global) {
var module = global.noise = {};
function Grad(x, y, z) {
this.x = x;
this.y = y;
this.z = z;
}
Grad.prototype.dot2 = function(x, y) {
return this.x*x + this.y*y;
};
Grad.prototype.dot3 = function(x, y, z) {
return this.x*x + this.y*y + this.z*z;
};
var grad3 = [
new Grad(1,1,0),new Grad(-1,1,0),new Grad(1,-1,0),new Grad(-1,-1,0),
new Grad(1,0,1),new Grad(-1,0,1),new Grad(1,0,-1),new Grad(-1,0,-1),
new Grad(0,1,1),new Grad(0,-1,1),new Grad(0,1,-1),new Grad(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];
// To avoid the need for index wrapping, double the permutation table length
var perm = new Array(512),
gradP = new Array(512);
// This isn't a very good seeding function, but it works okay. It supports
// 2^16 different seed values. Write your own if you need more seeds.
module.seed = function(seed) {
if (seed > 0 && seed < 1) {
// Scale the seed out
seed *= 65536;
}
seed = Math.floor(seed);
if (seed < 256) {
seed |= seed << 8;
}
for (var i = 0; i < 256; i++) {
var v;
if (i & 1) {
v = p[i] ^ (seed & 255);
}
else {
v = p[i] ^ ((seed>>8) & 255);
}
perm[i] = perm[i + 256] = v;
gradP[i] = gradP[i + 256] = grad3[v % 12];
}
};
module.seed(Math.random());
// Skewing and unskewing factors for 2 and 3 dimensions
var F2 = 0.5*(Math.sqrt(3)-1),
G2 = (3-Math.sqrt(3))/6,
F3 = 1/3,
G3 = 1/6;
// 2D simplex noise
module.simplex = function(xin, yin) {
var n0, n1, n2; // Noise contributions from the three corners
// Skew the input space to determine which simplex cell we're in
var s = (xin+yin)*F2; // Hairy factor for 2D
var i = Math.floor(xin+s);
var j = Math.floor(yin+s);
var t = (i+j)*G2;
var x0 = xin-i+t; // The x,y distances from the cell origin, unskewed
var y0 = yin-j+t;
// For the 2D case, the simplex shape is an equilateral triangle.
// Determine which simplex we are in.
var i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords
if (x0 > y0) { // Lower triangle, XY order: (0,0)->(1,0)->(1,1)
i1 = 1; j1 = 0;
}
else { // Upper triangle, YX order: (0,0)->(0,1)->(1,1)
i1 = 0; j1 = 1;
}
// A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
// a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
// c = (3-sqrt(3))/6
var x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
var y1 = y0 - j1 + G2;
var x2 = x0 - 1 + 2 * G2; // Offsets for last corner in (x,y) unskewed coords
var y2 = y0 - 1 + 2 * G2;
// Work out the hashed gradient indices of the three simplex corners
i &= 255;
j &= 255;
var gi0 = gradP[i+perm[j]];
var gi1 = gradP[i+i1+perm[j+j1]];
var gi2 = gradP[i+1+perm[j+1]];
// Calculate the contribution from the three corners
var t0 = 0.5 - x0*x0-y0*y0;
if (t0 < 0) {
n0 = 0;
}
else {
t0 *= t0;
n0 = t0 * t0 * gi0.dot2(x0, y0); // (x,y) of grad3 used for 2D gradient
}
var t1 = 0.5 - x1*x1-y1*y1;
if (t1 < 0) {
n1 = 0;
}
else {
t1 *= t1;
n1 = t1 * t1 * gi1.dot2(x1, y1);
}
var t2 = 0.5 - x2*x2-y2*y2;
if (t2 < 0) {
n2 = 0;
}
else {
t2 *= t2;
n2 = t2 * t2 * gi2.dot2(x2, y2);
}
// Add contributions from each corner to get the final noise value.
// The result is scaled to return values in the interval [-1,1].
return 70 * (n0 + n1 + n2);
};
// ##### Perlin noise stuff
function fade(t) {
return t*t*t*(t*(t*6-15)+10);
}
function lerp(a, b, t) {
return (1-t)*a + t*b;
}
// 2D Perlin Noise
module.perlin = function(x, y) {
// Find unit grid cell containing point
var X = Math.floor(x),
Y = Math.floor(y);
// Get relative xy coordinates of point within that cell
x = x - X;
y = y - Y;
// Wrap the integer cells at 255 (smaller integer period can be introduced here)
X = X & 255;
Y = Y & 255;
// Calculate noise contributions from each of the four corners
var n00 = gradP[X+perm[Y]].dot2(x, y);
var n01 = gradP[X+perm[Y+1]].dot2(x, y-1);
var n10 = gradP[X+1+perm[Y]].dot2(x-1, y);
var n11 = gradP[X+1+perm[Y+1]].dot2(x-1, y-1);
// Compute the fade curve value for x
var u = fade(x);
// Interpolate the four results
return lerp(
lerp(n00, n10, u),
lerp(n01, n11, u),
fade(y)
);
};
})(this);