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simplex.js
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simplex.js
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/**
* A fast javascript implementation of simplex noise based on sources
* of Jonas Wagner. https://github.com/jwagner/simplex-noise.js. Added
* octaves, amplitude, scale and distribution parameters. Good explanation
* of these parameters may be found here: https://www.redblobgames.com/maps/terrain-from-noise.
* Only 3D version + time are implemented. By default all configs === 1
*
* Config:
* scale [0..1] - zoom coefficient. 0 - max zoom, 1 - min zoom
* amplitude [0..1] - means: take all possible height values (1) or only part of it (< 1)
* distrib [0..X] - 0..1 - get values from top, 1..X get values from buttom
* octaves [1..X] - amount of details of a 3D map
* random - reference to random function, which return values between 0..1
*
* Example:
* let simplex = new Simplex();
* let t = 0;
*
* function drawNoise(width, height) {
* for (let x = 0; x < width; x++) {
* for (let y = 0; y < height; y++) {
* z = simplex.noise(x, y, t);
* // draw x,y,z point
* }
* }
* t += .001;
* }
* ...
* drawNoise(128, 128);
*
* @author flatline
*/
const F3 = 1.0 / 3.0;
const G3 = 1.0 / 6.0;
/**
* Creates simplex noise class instance with options
*/
class Simplex {
constructor(cfg) {
cfg = cfg || {};
this.amplitude = cfg.amplitude || 1.0;
this.distrib = cfg.distrib || 1.0;
this.scale = cfg.scale || 1.0;
this.octaves = cfg.octaves || 1;
this.random = cfg.random || Math.random;
this.grad3 = new Float32Array([
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.grad4 = new Float32Array([
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
]);
const p = this.p = this._buildPermutationTable(Math.random);
const perm = this.perm = new Uint8Array(512);
const pMod12 = this.permMod12 = new Uint8Array(512);
for (let i = 0; i < 512; i++) {
perm[i] = p[i & 255];
pMod12[i] = perm[i] % 12;
}
}
/**
* Does simplex noise. Returns height by (x,y) and time (t)
* @param {Number} x X
* @param {Number} y Y
* @param {Number} t Time
*/
noise(x, y, t) {
t = t || 0;
let amplitude = this.amplitude;
let scale = this.scale;
let noise = 0;
for (let i = 0, l = this.octaves; i < l; i++) {
noise += (this.rawNoise(x * scale, y * scale, t) * amplitude);
amplitude *= .5;
scale *= 2;
}
return Math.pow((noise + 1) / 2, this.distrib);
}
rawNoise(xin, yin, tin) {
const permMod12 = this.permMod12;
const perm = this.perm;
const grad3 = this.grad3;
let n0, n1, n2, n3; // Noise contributions from the four corners
// Skew the input space to determine which simplex cell we're in
const s = (xin + yin + tin) * F3; // Very nice and simple skew factor for 3D
const i = Math.floor(xin + s);
const j = Math.floor(yin + s);
const k = Math.floor(tin + s);
const t = (i + j + k) * G3;
const X0 = i - t; // Unskew the cell origin back to (x,y,z) space
const Y0 = j - t;
const Z0 = k - t;
const x0 = xin - X0; // The x,y,z distances from the cell origin
const y0 = yin - Y0;
const z0 = tin - Z0;
// For the 3D case, the simplex shape is a slightly irregular tetrahedron.
// Determine which simplex we are in.
let i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords
let i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords
if (x0 >= y0) {
if (y0 >= z0) {
i1 = 1;
j1 = 0;
k1 = 0;
i2 = 1;
j2 = 1;
k2 = 0;
} // X Y Z order
else if (x0 >= z0) {
i1 = 1;
j1 = 0;
k1 = 0;
i2 = 1;
j2 = 0;
k2 = 1;
} // X Z Y order
else {
i1 = 0;
j1 = 0;
k1 = 1;
i2 = 1;
j2 = 0;
k2 = 1;
} // Z X Y order
}
else { // x0<y0
if (y0 < z0) {
i1 = 0;
j1 = 0;
k1 = 1;
i2 = 0;
j2 = 1;
k2 = 1;
} // Z Y X order
else if (x0 < z0) {
i1 = 0;
j1 = 1;
k1 = 0;
i2 = 0;
j2 = 1;
k2 = 1;
} // Y Z X order
else {
i1 = 0;
j1 = 1;
k1 = 0;
i2 = 1;
j2 = 1;
k2 = 0;
} // Y X Z order
}
// A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
// a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
// a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
// c = 1/6.
const x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
const y1 = y0 - j1 + G3;
const z1 = z0 - k1 + G3;
const x2 = x0 - i2 + 2.0 * G3; // Offsets for third corner in (x,y,z) coords
const y2 = y0 - j2 + 2.0 * G3;
const z2 = z0 - k2 + 2.0 * G3;
const x3 = x0 - 1.0 + 3.0 * G3; // Offsets for last corner in (x,y,z) coords
const y3 = y0 - 1.0 + 3.0 * G3;
const z3 = z0 - 1.0 + 3.0 * G3;
// Work out the hashed gradient indices of the four simplex corners
const ii = i & 255;
const jj = j & 255;
const kk = k & 255;
// Calculate the contribution from the four corners
let t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0;
if (t0 < 0) n0 = 0.0;
else {
const gi0 = permMod12[ii + perm[jj + perm[kk]]] * 3;
t0 *= t0;
n0 = t0 * t0 * (grad3[gi0] * x0 + grad3[gi0 + 1] * y0 + grad3[gi0 + 2] * z0);
}
let t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1;
if (t1 < 0) n1 = 0.0;
else {
const gi1 = permMod12[ii + i1 + perm[jj + j1 + perm[kk + k1]]] * 3;
t1 *= t1;
n1 = t1 * t1 * (grad3[gi1] * x1 + grad3[gi1 + 1] * y1 + grad3[gi1 + 2] * z1);
}
let t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2;
if (t2 < 0) n2 = 0.0;
else {
const gi2 = permMod12[ii + i2 + perm[jj + j2 + perm[kk + k2]]] * 3;
t2 *= t2;
n2 = t2 * t2 * (grad3[gi2] * x2 + grad3[gi2 + 1] * y2 + grad3[gi2 + 2] * z2);
}
let t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3;
if (t3 < 0) n3 = 0.0;
else {
const gi3 = permMod12[ii + 1 + perm[jj + 1 + perm[kk + 1]]] * 3;
t3 *= t3;
n3 = t3 * t3 * (grad3[gi3] * x3 + grad3[gi3 + 1] * y3 + grad3[gi3 + 2] * z3);
}
// Add contributions from each corner to get the final noise value.
// The result is scaled to stay just inside [-1,1]
return 32.0 * (n0 + n1 + n2 + n3);
}
/**
* Initialization method
* @param {Function} random function reference
*/
_buildPermutationTable(random) {
const p = new Uint8Array(256);
for (let i = 0; i < 256; i++) {p[i] = i}
for (let i = 0; i < 255; i++) {
const r = i + ~~(random() * (256 - i));
var aux = p[i];
p[i] = p[r];
p[r] = aux;
}
return p;
}
}