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Code adapted and cleaned up from the C# implementation here http://flafla2.github.io/2014/08/09/perlinnoise.html. Specific changes: conversion to JS, removal of classes and stateful classes.
// Hash lookup table as defined by Ken Perlin. This is a randomly
// arranged array of all numbers from 0-255 inclusive.
const permutation = [ 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
];
const pp = [];
for (let i = 0; i < 512; i++) {
pp[i] = permutation[i % 256];
}
// Source: http://riven8192.blogspot.com/2010/08/calculate-perlinnoise-twice-as-fast.html
function grad(hash, x, y, z) {
switch(hash & 0xF) {
case 0x0: return x + y;
case 0x1: return -x + y;
case 0x2: return x - y;
case 0x3: return -x - y;
case 0x4: return x + z;
case 0x5: return -x + z;
case 0x6: return x - z;
case 0x7: return -x - z;
case 0x8: return y + z;
case 0x9: return -y + z;
case 0xA: return y - z;
case 0xB: return -y - z;
case 0xC: return y + x;
case 0xD: return -y + z;
case 0xE: return y - x;
case 0xF: return -y - z;
default: return 0; // never happens
}
}
// Fade function as defined by Ken Perlin. This eases coordinate values
// so that they will "ease" towards integral values. This ends up smoothing
// the final output.
function fade(t) {
// 6t^5 - 15t^4 + 10t^3
return t * t * t * (t * (t * 6 - 15) + 10);
}
function inc(num, repeat) {
num++;
if (repeat > 0) num %= repeat;
return num;
}
function lerp(a, b, x) {
return a + x * (b - a);
}
// Make sure that x, y, z are within 0-1! Otherwise you will just see 0.5.
export function Perlin(x, y, z, repeat = 0) {
// If we have any repeat on, change the coordinates to their "local" repetitions
if (repeat > 0) {
x = x % repeat;
y = y % repeat;
z = z % repeat;
}
// Calculate the "unit cube" that the point asked will be located in
// The left bound is ( |_x_|,|_y_|,|_z_| ) and the right bound is that
// plus 1. Next we calculate the location (from 0.0 to 1.0) in that cube.
// We also fade the location to smooth the result.
const xi = Math.floor(x) & 255;
const yi = Math.floor(y) & 255;
const zi = Math.floor(z) & 255;
const xf = x - Math.floor(x);
const yf = y - Math.floor(y);
const zf = z - Math.floor(z);
const u = fade(xf);
const v = fade(yf);
const w = fade(zf);
const aaa = pp[pp[pp[xi] + yi] + zi];
const aba = pp[pp[pp[xi] + inc(yi, repeat)] + zi];
const aab = pp[pp[pp[xi] + yi] + inc(zi, repeat)];
const abb = pp[pp[pp[xi] + inc(yi, repeat)] + inc(zi, repeat)];
const baa = pp[pp[pp[inc(xi, repeat)] + yi] + zi];
const bba = pp[pp[pp[inc(xi, repeat)] + inc(yi, repeat)] + zi];
const bab = pp[pp[pp[inc(xi, repeat)] + yi] + inc(zi, repeat)];
const bbb = pp[pp[pp[inc(xi, repeat)] + inc(yi, repeat)] + inc(zi, repeat)];
// The gradient function calculates the dot product between a pseudorandom
// gradient vector and the vector from the input coordinate to the 8
// surrounding points in its unit cube.
// This is all then lerped together as a sort of weighted average based on the faded (u,v,w)
// values we made earlier.
let x1, x2, y1, y2;
x1 = lerp(grad(aaa, xf, yf, zf), grad(baa, xf - 1, yf, zf), u);
x2 = lerp(grad(aba, xf, yf - 1, zf), grad(bba, xf - 1, yf - 1, zf), u);
y1 = lerp(x1, x2, v);
x1 = lerp(grad(aab, xf, yf, zf - 1), grad(bab, xf - 1, yf, zf - 1), u);
x2 = lerp(grad(abb, xf, yf - 1, zf - 1), grad(bbb, xf - 1, yf - 1, zf - 1), u);
y2 = lerp(x1, x2, v);
// For convenience we bound it to 0 - 1 (theoretical min/max before is -1 - 1)
return (lerp (y1, y2, w)+1)/2;
}
// Make sure that x, y, z are within 0-1! Otherwise you will just see 0.5.
export function OctavePerlin(x, y, z, octaves, persistence, repeat=0) {
let total = 0;
let frequency = 1;
let amplitude = 1;
// Used for normalizing result to 0.0 - 1.0
let maxValue = 0;
for(let i = 0; i < octaves; i++) {
total += Perlin(x * frequency, y * frequency, z * frequency, repeat) * amplitude;
maxValue += amplitude;
amplitude *= persistence;
frequency *= 2;
}
return total/maxValue;
}
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