three.js/examples/jsm/math/ImprovedNoise.js

const _p = [ 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 ];

for ( let i = 0; i < 256; i ++ ) {

	_p[ 256 + i ] = _p[ i ];

}

function fade( t ) {

	return t * t * t * ( t * ( t * 6 - 15 ) + 10 );

}

function lerp( t, a, b ) {

	return a + t * ( b - a );

}

function grad( hash, x, y, z ) {

	const h = hash & 15;
	const u = h < 8 ? x : y, v = h < 4 ? y : h == 12 || h == 14 ? x : z;
	return ( ( h & 1 ) == 0 ? u : - u ) + ( ( h & 2 ) == 0 ? v : - v );

}

/**
 * A utility class providing a 3D noise function.
 *
 * The code is based on [IMPROVED NOISE]{@link https://cs.nyu.edu/~perlin/noise/}
 * by Ken Perlin, 2002.
 */
class ImprovedNoise {

	/**
	 * Returns a noise value for the given parameters.
	 *
	 * @param {number} x - The x coordinate.
	 * @param {number} y - The y coordinate.
	 * @param {number} z - The z coordinate.
	 * @return {number} The noise value.
	 */
	noise( x, y, z ) {

		const floorX = Math.floor( x ), floorY = Math.floor( y ), floorZ = Math.floor( z );

		const X = floorX & 255, Y = floorY & 255, Z = floorZ & 255;

		x -= floorX;
		y -= floorY;
		z -= floorZ;

		const xMinus1 = x - 1, yMinus1 = y - 1, zMinus1 = z - 1;

		const u = fade( x ), v = fade( y ), w = fade( z );

		const A = _p[ X ] + Y, AA = _p[ A ] + Z, AB = _p[ A + 1 ] + Z, B = _p[ X + 1 ] + Y, BA = _p[ B ] + Z, BB = _p[ B + 1 ] + Z;

		return lerp( w, lerp( v, lerp( u, grad( _p[ AA ], x, y, z ),
			grad( _p[ BA ], xMinus1, y, z ) ),
		lerp( u, grad( _p[ AB ], x, yMinus1, z ),
			grad( _p[ BB ], xMinus1, yMinus1, z ) ) ),
		lerp( v, lerp( u, grad( _p[ AA + 1 ], x, y, zMinus1 ),
			grad( _p[ BA + 1 ], xMinus1, y, zMinus1 ) ),
		lerp( u, grad( _p[ AB + 1 ], x, yMinus1, zMinus1 ),
			grad( _p[ BB + 1 ], xMinus1, yMinus1, zMinus1 ) ) ) );

	}

}

export { ImprovedNoise };