fast-simplex-noise
Version:
A TypeScript implementation of faster simplex noise
84 lines (83 loc) • 2.9 kB
JavaScript
"use strict";
/*
* Based on example code by Stefan Gustavson (stegu@itn.liu.se).
* Optimisations by Peter Eastman (peastman@drizzle.stanford.edu).
* Better rank ordering method by Stefan Gustavson in 2012.
*
* This code was placed in the public domain by its original author,
* Stefan Gustavson. You may use it as you see fit, but
* attribution is appreciated.
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.makeNoise2D = void 0;
var G2 = (3.0 - Math.sqrt(3.0)) / 6.0;
var Grad = [
[1, 1],
[-1, 1],
[1, -1],
[-1, -1],
[1, 0],
[-1, 0],
[1, 0],
[-1, 0],
[0, 1],
[0, -1],
[0, 1],
[0, -1],
];
function makeNoise2D(random) {
if (random === void 0) { random = Math.random; }
var p = new Uint8Array(256);
for (var i = 0; i < 256; i++)
p[i] = i;
var n;
var q;
for (var i = 255; i > 0; i--) {
n = Math.floor((i + 1) * random());
q = p[i];
p[i] = p[n];
p[n] = q;
}
var perm = new Uint8Array(512);
var permMod12 = new Uint8Array(512);
for (var i = 0; i < 512; i++) {
perm[i] = p[i & 255];
permMod12[i] = perm[i] % 12;
}
return function (x, y) {
// Skew the input space to determine which simplex cell we're in
var s = (x + y) * 0.5 * (Math.sqrt(3.0) - 1.0); // Hairy factor for 2D
var i = Math.floor(x + s);
var j = Math.floor(y + s);
var t = (i + j) * G2;
var X0 = i - t; // Unskew the cell origin back to (x,y) space
var Y0 = j - t;
var x0 = x - X0; // The x,y distances from the cell origin
var y0 = y - Y0;
// Determine which simplex we are in.
var i1 = x0 > y0 ? 1 : 0;
var j1 = x0 > y0 ? 0 : 1;
// Offsets for corners
var x1 = x0 - i1 + G2;
var y1 = y0 - j1 + G2;
var x2 = x0 - 1.0 + 2.0 * G2;
var y2 = y0 - 1.0 + 2.0 * G2;
// Work out the hashed gradient indices of the three simplex corners
var ii = i & 255;
var jj = j & 255;
var g0 = Grad[permMod12[ii + perm[jj]]];
var g1 = Grad[permMod12[ii + i1 + perm[jj + j1]]];
var g2 = Grad[permMod12[ii + 1 + perm[jj + 1]]];
// Calculate the contribution from the three corners
var t0 = 0.5 - x0 * x0 - y0 * y0;
var n0 = t0 < 0 ? 0.0 : Math.pow(t0, 4) * (g0[0] * x0 + g0[1] * y0);
var t1 = 0.5 - x1 * x1 - y1 * y1;
var n1 = t1 < 0 ? 0.0 : Math.pow(t1, 4) * (g1[0] * x1 + g1[1] * y1);
var t2 = 0.5 - x2 * x2 - y2 * y2;
var n2 = t2 < 0 ? 0.0 : Math.pow(t2, 4) * (g2[0] * x2 + g2[1] * 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 70.14805770653952 * (n0 + n1 + n2);
};
}
exports.makeNoise2D = makeNoise2D;