fast-simplex-noise
Version:
A TypeScript implementation of faster simplex noise
187 lines (186 loc) • 6.82 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.makeNoise4D = void 0;
var G4 = (5.0 - Math.sqrt(5.0)) / 20.0;
var Grad = [
[0, 1, 1, 1],
[0, 1, 1, -1],
[0, 1, -1, 1],
[0, 1, -1, -1],
[0, -1, 1, 1],
[0, -1, 1, -1],
[0, -1, -1, 1],
[0, -1, -1, -1],
[1, 0, 1, 1],
[1, 0, 1, -1],
[1, 0, -1, 1],
[1, 0, -1, -1],
[-1, 0, 1, 1],
[-1, 0, 1, -1],
[-1, 0, -1, 1],
[-1, 0, -1, -1],
[1, 1, 0, 1],
[1, 1, 0, -1],
[1, -1, 0, 1],
[1, -1, 0, -1],
[-1, 1, 0, 1],
[-1, 1, 0, -1],
[-1, -1, 0, 1],
[-1, -1, 0, -1],
[1, 1, 1, 0],
[1, 1, -1, 0],
[1, -1, 1, 0],
[1, -1, -1, 0],
[-1, 1, 1, 0],
[-1, 1, -1, 0],
[-1, -1, 1, 0],
[-1, -1, -1, 0],
];
function makeNoise4D(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, z, w) {
// Skew the (x,y,z,w) space to determine which cell of 24 simplices we're in
var s = (x + y + z + w) * (Math.sqrt(5.0) - 1.0) / 4.0; // Factor for 4D skewing
var i = Math.floor(x + s);
var j = Math.floor(y + s);
var k = Math.floor(z + s);
var l = Math.floor(w + s);
var t = (i + j + k + l) * G4; // Factor for 4D unskewing
var X0 = i - t; // Unskew the cell origin back to (x,y,z,w) space
var Y0 = j - t;
var Z0 = k - t;
var W0 = l - t;
var x0 = x - X0; // The x,y,z,w distances from the cell origin
var y0 = y - Y0;
var z0 = z - Z0;
var w0 = w - W0;
// To find out which of the 24 possible simplices we're in, we need to determine the
// magnitude ordering of x0, y0, z0 and w0. Six pair-wise comparisons are performed between
// each possible pair of the four coordinates, and the results are used to rank the numbers.
var rankx = 0;
var ranky = 0;
var rankz = 0;
var rankw = 0;
if (x0 > y0)
rankx++;
else
ranky++;
if (x0 > z0)
rankx++;
else
rankz++;
if (x0 > w0)
rankx++;
else
rankw++;
if (y0 > z0)
ranky++;
else
rankz++;
if (y0 > w0)
ranky++;
else
rankw++;
if (z0 > w0)
rankz++;
else
rankw++;
// simplex[c] is a 4-vector with the numbers 0, 1, 2 and 3 in some order.
// Many values of c will never occur, since e.g. x>y>z>w makes x<z, y<w and x<w
// impossible. Only the 24 indices which have non-zero entries make any sense.
// We use a thresholding to set the coordinates in turn from the largest magnitude.
// Rank 3 denotes the largest coordinate.
var i1 = rankx >= 3 ? 1 : 0;
var j1 = ranky >= 3 ? 1 : 0;
var k1 = rankz >= 3 ? 1 : 0;
var l1 = rankw >= 3 ? 1 : 0;
// Rank 2 denotes the second largest coordinate.
var i2 = rankx >= 2 ? 1 : 0;
var j2 = ranky >= 2 ? 1 : 0;
var k2 = rankz >= 2 ? 1 : 0;
var l2 = rankw >= 2 ? 1 : 0;
// Rank 1 denotes the second smallest coordinate.
var i3 = rankx >= 1 ? 1 : 0;
var j3 = ranky >= 1 ? 1 : 0;
var k3 = rankz >= 1 ? 1 : 0;
var l3 = rankw >= 1 ? 1 : 0;
// The fifth corner has all coordinate offsets = 1, so no need to compute that.
var x1 = x0 - i1 + G4; // Offsets for second corner in (x,y,z,w) coords
var y1 = y0 - j1 + G4;
var z1 = z0 - k1 + G4;
var w1 = w0 - l1 + G4;
var x2 = x0 - i2 + 2.0 * G4; // Offsets for third corner in (x,y,z,w) coords
var y2 = y0 - j2 + 2.0 * G4;
var z2 = z0 - k2 + 2.0 * G4;
var w2 = w0 - l2 + 2.0 * G4;
var x3 = x0 - i3 + 3.0 * G4; // Offsets for fourth corner in (x,y,z,w) coords
var y3 = y0 - j3 + 3.0 * G4;
var z3 = z0 - k3 + 3.0 * G4;
var w3 = w0 - l3 + 3.0 * G4;
var x4 = x0 - 1.0 + 4.0 * G4; // Offsets for last corner in (x,y,z,w) coords
var y4 = y0 - 1.0 + 4.0 * G4;
var z4 = z0 - 1.0 + 4.0 * G4;
var w4 = w0 - 1.0 + 4.0 * G4;
// Work out the hashed gradient indices of the five simplex corners
var ii = i & 255;
var jj = j & 255;
var kk = k & 255;
var ll = l & 255;
var g0 = Grad[perm[ii + perm[jj + perm[kk + perm[ll]]]] %
32];
var g1 = Grad[perm[ii + i1 + perm[jj + j1 + perm[kk + k1 + perm[ll + l1]]]] % 32];
var g2 = Grad[perm[ii + i2 + perm[jj + j2 + perm[kk + k2 + perm[ll + l2]]]] % 32];
var g3 = Grad[perm[ii + i3 + perm[jj + j3 + perm[kk + k3 + perm[ll + l3]]]] % 32];
var g4 = Grad[perm[ii + 1 + perm[jj + 1 + perm[kk + 1 + perm[ll + 1]]]] % 32];
// Calculate the contribution from the five corners
var t0 = 0.5 - x0 * x0 - y0 * y0 - z0 * z0 - w0 * w0;
var n0 = t0 < 0
? 0.0
: Math.pow(t0, 4) * (g0[0] * x0 + g0[1] * y0 + g0[2] * z0 + g0[3] * w0);
var t1 = 0.5 - x1 * x1 - y1 * y1 - z1 * z1 - w1 * w1;
var n1 = t1 < 0
? 0.0
: Math.pow(t1, 4) * (g1[0] * x1 + g1[1] * y1 + g1[2] * z1 + g1[3] * w1);
var t2 = 0.5 - x2 * x2 - y2 * y2 - z2 * z2 - w2 * w2;
var n2 = t2 < 0
? 0.0
: Math.pow(t2, 4) * (g2[0] * x2 + g2[1] * y2 + g2[2] * z2 + g2[3] * w2);
var t3 = 0.5 - x3 * x3 - y3 * y3 - z3 * z3 - w3 * w3;
var n3 = t3 < 0
? 0.0
: Math.pow(t3, 4) * (g3[0] * x3 + g3[1] * y3 + g3[2] * z3 + g3[3] * w3);
var t4 = 0.5 - x4 * x4 - y4 * y4 - z4 * z4 - w4 * w4;
var n4 = t4 < 0
? 0.0
: Math.pow(t4, 4) * (g4[0] * x4 + g4[1] * y4 + g4[2] * z4 + g4[3] * w4);
// Sum up and scale the result to cover the range [-1,1]
return 72.37855765153665 * (n0 + n1 + n2 + n3 + n4);
};
}
exports.makeNoise4D = makeNoise4D;