Noise.java

package com.bitwaffle.spaceguts.util;

/**
 * Perlin noise generator, taken from <a href="http://cs.nyu.edu/~perlin/noise/">Improved Noise reference implementation by Ken Perlin</a>
 * @author TranquilMarmot
 *
 */
public class Noise {
	/**
	 * JAVA REFERENCE IMPLEMENTATION OF IMPROVED NOISE - COPYRIGHT 2002 KEN
	 * PERLIN.
	 * 
	 * @param x
	 *            X value
	 * @param y
	 *            Y value
	 * @param z
	 *            Z value
	 * @return A value between 0 and 1
	 */
	public static double noise(double x, double y, double z) {
		int X = (int) Math.floor(x) & 255, // FIND UNIT CUBE THAT
		Y = (int) Math.floor(y) & 255, // CONTAINS POINT.
		Z = (int) Math.floor(z) & 255;
		x -= Math.floor(x); // FIND RELATIVE X,Y,Z
		y -= Math.floor(y); // OF POINT IN CUBE.
		z -= Math.floor(z);
		double u = fade(x), // COMPUTE FADE CURVES
		v = fade(y), // FOR EACH OF X,Y,Z.
		w = fade(z);
		int A = p[X] + Y, AA = p[A] + Z, AB = p[A + 1] + Z, // HASH COORDINATES
															// OF
		B = p[X + 1] + Y, BA = p[B] + Z, BB = p[B + 1] + Z; // THE 8 CUBE
															// CORNERS,

		return lerp(w,
				lerp(v, lerp(u, grad(p[AA], x, y, z), // AND ADD
						grad(p[BA], x - 1, y, z)), // BLENDED
						lerp(u, grad(p[AB], x, y - 1, z), // RESULTS
								grad(p[BB], x - 1, y - 1, z))),// FROM 8
				lerp(v,
						lerp(u, grad(p[AA + 1], x, y, z - 1), // CORNERS
								grad(p[BA + 1], x - 1, y, z - 1)), // OF CUBE
						lerp(u, grad(p[AB + 1], x, y - 1, z - 1),
								grad(p[BB + 1], x - 1, y - 1, z - 1))));
	}

	static double fade(double t) {
		return t * t * t * (t * (t * 6 - 15) + 10);
	}

	static double lerp(double t, double a, double b) {
		return a + t * (b - a);
	}

	static double grad(int hash, double x, double y, double z) {
		int h = hash & 15; // CONVERT LO 4 BITS OF HASH CODE
		double u = h < 8 ? x : y, // INTO 12 GRADIENT DIRECTIONS.
		v = h < 4 ? y : h == 12 || h == 14 ? x : z;
		return ((h & 1) == 0 ? u : -u) + ((h & 2) == 0 ? v : -v);
	}

	static final int p[] = new int[512], 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 };
	static {
		for (int i = 0; i < 256; i++)
			p[256 + i] = p[i] = permutation[i];
	}
}