75e51619df
Automated salvage commit — agent session ended (exit 124). Work in progress, may need continuation.
49 lines
1.8 KiB
JavaScript
49 lines
1.8 KiB
JavaScript
// modules/utils/perlin.js — Perlin noise generator
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/**
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* Creates a seeded Perlin noise function.
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* Uses a fixed seed (42) for deterministic terrain generation.
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*
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* @returns {function(x: number, y: number, z?: number): number} noise function
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*/
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export function createPerlinNoise() {
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const p = new Uint8Array(256);
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for (let i = 0; i < 256; i++) p[i] = i;
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let seed = 42;
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function seededRand() {
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seed = (seed * 1664525 + 1013904223) & 0xffffffff;
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return (seed >>> 0) / 0xffffffff;
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}
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for (let i = 255; i > 0; i--) {
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const j = Math.floor(seededRand() * (i + 1));
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const tmp = p[i]; p[i] = p[j]; p[j] = tmp;
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}
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const perm = new Uint8Array(512);
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for (let i = 0; i < 512; i++) perm[i] = p[i & 255];
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function fade(t) { return t * t * t * (t * (t * 6 - 15) + 10); }
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function lerp(a, b, t) { return a + t * (b - a); }
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function grad(hash, x, y, z) {
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const h = hash & 15;
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const u = h < 8 ? x : y;
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const v = h < 4 ? y : (h === 12 || h === 14) ? x : z;
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return ((h & 1) ? -u : u) + ((h & 2) ? -v : v);
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}
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return function noise(x, y, z) {
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z = z || 0;
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const X = Math.floor(x) & 255, Y = Math.floor(y) & 255, Z = Math.floor(z) & 255;
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x -= Math.floor(x); y -= Math.floor(y); z -= Math.floor(z);
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const u = fade(x), v = fade(y), w = fade(z);
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const A = perm[X] + Y, AA = perm[A] + Z, AB = perm[A + 1] + Z;
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const B = perm[X + 1] + Y, BA = perm[B] + Z, BB = perm[B + 1] + Z;
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return lerp(
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lerp(lerp(grad(perm[AA], x, y, z ), grad(perm[BA], x-1, y, z ), u),
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lerp(grad(perm[AB], x, y-1, z ), grad(perm[BB], x-1, y-1, z ), u), v),
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lerp(lerp(grad(perm[AA + 1], x, y, z-1), grad(perm[BA + 1], x-1, y, z-1), u),
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lerp(grad(perm[AB + 1], x, y-1, z-1), grad(perm[BB + 1], x-1, y-1, z-1), u), v),
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w
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);
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};
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}
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