Added a Perlin and Simplex noise generator for utils

3 files changed, 843 insertions, 0 deletions

diff --git a/src/main/java/org/bukkit/util/noise/NoiseGenerator.java b/src/main/java/org/bukkit/util/noise/NoiseGenerator.java
new file mode 100644
index 00000000..823528fc
--- /dev/null
+++ b/src/main/java/org/bukkit/util/noise/NoiseGenerator.java
@@ -0,0 +1,120 @@
+
+package org.bukkit.util.noise;
+
+/**
+ * Base class for all noise generators
+ */
+public abstract class NoiseGenerator {
+    protected final int perm[] = new int[512];
+    protected double offsetX;
+    protected double offsetY;
+    protected double offsetZ;
+
+    /**
+     * Speedy floor, faster than (int)Math.floor(x)
+     * 
+     * @param x Value to floor
+     * @return Floored value
+     */
+    public static int floor(double x) {
+        return (int)Math.floor(x);
+    }
+
+    protected static double fade(double x) {
+        return x * x * x * (x * (x * 6 - 15) + 10);
+    }
+
+    protected static double lerp(double x, double y, double z) {
+        return y + x * (z - y);
+    }
+
+    protected static double grad(int hash, double x, double y, double z) {
+        hash &= 15;
+        double u = hash < 8 ? x : y;
+        double v = hash < 4 ? y : hash == 12 || hash == 14 ? x : z;
+        return ((hash & 1) == 0 ? u : -u) + ((hash & 2) == 0 ? v : -v);
+    }
+
+    /**
+     * Computes and returns the 1D noise for the given coordinate in 1D space
+     *
+     * @param x X coordinate
+     * @return Noise at given location, from range -1 to 1
+     */
+    public double noise(double x) {
+        return noise(x, 0, 0);
+    }
+
+    /**
+     * Computes and returns the 2D noise for the given coordinates in 2D space
+     *
+     * @param x X coordinate
+     * @param y Y coordinate
+     * @return Noise at given location, from range -1 to 1
+     */
+    public double noise(double x, double y) {
+        return noise(x, y, 0);
+    }
+
+    /**
+     * Computes and returns the 3D noise for the given coordinates in 3D space
+     *
+     * @param x X coordinate
+     * @param y Y coordinate
+     * @param z Z coordinate
+     * @return Noise at given location, from range -1 to 1
+     */
+    public abstract double noise(double x, double y, double z);
+
+    /**
+     * Generates noise for the 1D coordinates using the specified number of octaves and parameters
+     *
+     * @param x X-coordinate
+     * @param octaves Number of octaves to use
+     * @param frequency How much to alter the frequency by each octave
+     * @param amplitude How much to alter the amplitude by each octave
+     * @return Resulting noise
+     */
+    public double noise(double x, int octaves, double frequency, double amplitude) {
+        return noise(x, 0, 0, octaves, frequency, amplitude);
+    }
+
+    /**
+     * Generates noise for the 2D coordinates using the specified number of octaves and parameters
+     *
+     * @param x X-coordinate
+     * @param y Y-coordinate
+     * @param octaves Number of octaves to use
+     * @param frequency How much to alter the frequency by each octave
+     * @param amplitude How much to alter the amplitude by each octave
+     * @return Resulting noise
+     */
+    public double noise(double x, double y, int octaves, double frequency, double amplitude) {
+        return noise(x, y, 0, octaves, frequency, amplitude);
+    }
+
+    /**
+     * Generates noise for the 3D coordinates using the specified number of octaves and parameters
+     *
+     * @param x X-coordinate
+     * @param y Y-coordinate
+     * @param z Z-coordinate
+     * @param octaves Number of octaves to use
+     * @param frequency How much to alter the frequency by each octave
+     * @param amplitude How much to alter the amplitude by each octave
+     * @return Resulting noise
+     */
+    public double noise(double x, double y, double z, int octaves, double frequency, double amplitude) {
+        double result = 0;
+        double amp = 1;
+        double freq = 1;
+
+        for (int i = 0; i < octaves; i++) {
+            result += noise(x * freq, y * freq, z * freq) * amp;
+            freq *= frequency;
+            amp *= amplitude;
+        }
+
+        return result;
+    }
+}
diff --git a/src/main/java/org/bukkit/util/noise/PerlinNoiseGenerator.java b/src/main/java/org/bukkit/util/noise/PerlinNoiseGenerator.java
new file mode 100644
index 00000000..1ac77420
--- /dev/null
+++ b/src/main/java/org/bukkit/util/noise/PerlinNoiseGenerator.java
@@ -0,0 +1,210 @@
+package org.bukkit.util.noise;
+
+import java.util.Random;
+import org.bukkit.World;
+
+/**
+ * Generates noise using the "classic" perlin generator
+ * 
+ * @see SimplexNoiseGenerator "Improved" and faster version with slighly different results
+ */
+public class PerlinNoiseGenerator extends NoiseGenerator {
+    protected static final int grad3[][] = {{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}};
+    private static final PerlinNoiseGenerator instance = new PerlinNoiseGenerator();
+
+    protected PerlinNoiseGenerator() {
+        int 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 (int i = 0; i < 512; i++) {
+            perm[i] = p[i & 255];
+        }
+    }
+
+    /**
+     * Creates a seeded perlin noise generator for the given world
+     *
+     * @param world World to construct this generator for
+     */
+    public PerlinNoiseGenerator(World world) {
+        this(new Random(world.getSeed()));
+    }
+
+    /**
+     * Creates a seeded perlin noise generator for the given seed
+     *
+     * @param seed Seed to construct this generator for
+     */
+    public PerlinNoiseGenerator(long seed) {
+        this(new Random(seed));
+    }
+
+    /**
+     * Creates a seeded perlin noise generator with the given Random
+     *
+     * @param rand Random to construct with
+     */
+    public PerlinNoiseGenerator(Random rand) {
+        offsetX = rand.nextDouble() * 256;
+        offsetY = rand.nextDouble() * 256;
+        offsetZ = rand.nextDouble() * 256;
+
+        for (int i = 0; i < 256; i++) {
+            perm[i] = i;
+        }
+
+        for (int i = 0; i < 256; i++) {
+            int pos = rand.nextInt(256 - i) + i;
+            int old = perm[i];
+
+            perm[i] = perm[pos];
+            perm[pos] = old;
+            perm[i + 256] = perm[i];
+        }
+    }
+
+    /**
+     * Computes and returns the 1D unseeded perlin noise for the given coordinates in 1D space
+     *
+     * @param x X coordinate
+     * @return Noise at given location, from range -1 to 1
+     */
+    public static double getNoise(double x) {
+        return instance.noise(x);
+    }
+
+    /**
+     * Computes and returns the 2D unseeded perlin noise for the given coordinates in 2D space
+     *
+     * @param x X coordinate
+     * @param y Y coordinate
+     * @return Noise at given location, from range -1 to 1
+     */
+    public static double getNoise(double x, double y) {
+        return instance.noise(x, y);
+    }
+
+    /**
+     * Computes and returns the 3D unseeded perlin noise for the given coordinates in 3D space
+     *
+     * @param x X coordinate
+     * @param y Y coordinate
+     * @param z Z coordinate
+     * @return Noise at given location, from range -1 to 1
+     */
+    public static double getNoise(double x, double y, double z) {
+        return instance.noise(x, y, z);
+    }
+
+    /**
+     * Gets the singleton unseeded instance of this generator
+     *
+     * @return Singleton
+     */
+    public static PerlinNoiseGenerator getInstance() {
+        return instance;
+    }
+
+    @Override
+    public double noise(double x, double y, double z) {
+        x += offsetX;
+        y += offsetY;
+        z += offsetZ;
+
+        int floorX = floor(x);
+        int floorY = floor(y);
+        int floorZ = floor(z);
+
+        // Find unit cube containing the point
+        int X = floorX & 255;
+        int Y = floorY & 255;
+        int Z = floorZ & 255;
+
+        // Get relative xyz coordinates of the point within the cube
+        x -= floorX;
+        y -= floorY;
+        z -= floorZ;
+
+        // Compute fade curves for xyz
+        double fX = fade(x);
+        double fY = fade(y);
+        double fZ = fade(z);
+
+        // Hash coordinates of the cube corners
+        int A = perm[X] + Y;
+        int AA = perm[A] + Z;
+        int AB = perm[A + 1] + Z;
+        int B = perm[X + 1] + Y;
+        int BA = perm[B] + Z;
+        int BB = perm[B + 1] + Z;
+
+        return lerp(fZ, lerp(fY, lerp(fX, grad(perm[AA], x, y, z),
+                        grad(perm[BA], x - 1, y, z)),
+                    lerp(fX, grad(perm[AB], x, y - 1, z),
+                        grad(perm[BB], x - 1, y - 1, z))),
+                lerp(fY, lerp(fX, grad(perm[AA + 1], x, y, z - 1),
+                        grad(perm[BA + 1], x - 1, y, z - 1)),
+                    lerp(fX, grad(perm[AB + 1], x, y - 1, z - 1),
+                        grad(perm[BB + 1], x - 1, y - 1, z - 1))));
+    }
+
+    /**
+     * Generates noise for the 1D coordinates using the specified number of octaves and parameters
+     *
+     * @param x X-coordinate
+     * @param octaves Number of octaves to use
+     * @param frequency How much to alter the frequency by each octave
+     * @param amplitude How much to alter the amplitude by each octave
+     * @return Resulting noise
+     */
+    public static double getNoise(double x, int octaves, double frequency, double amplitude) {
+        return instance.noise(x, octaves, frequency, amplitude);
+    }
+
+    /**
+     * Generates noise for the 2D coordinates using the specified number of octaves and parameters
+     *
+     * @param x X-coordinate
+     * @param y Y-coordinate
+     * @param octaves Number of octaves to use
+     * @param frequency How much to alter the frequency by each octave
+     * @param amplitude How much to alter the amplitude by each octave
+     * @return Resulting noise
+     */
+    public double getNoise(double x, double y, int octaves, double frequency, double amplitude) {
+        return instance.noise(x, y, octaves, frequency, amplitude);
+    }
+
+    /**
+     * Generates noise for the 3D coordinates using the specified number of octaves and parameters
+     *
+     * @param x X-coordinate
+     * @param y Y-coordinate
+     * @param z Z-coordinate
+     * @param octaves Number of octaves to use
+     * @param frequency How much to alter the frequency by each octave
+     * @param amplitude How much to alter the amplitude by each octave
+     * @return Resulting noise
+     */
+    public double getNoise(double x, double y, double z, int octaves, double frequency, double amplitude) {
+        return instance.noise(x, y, z, octaves, frequency, amplitude);
+    }
+}
diff --git a/src/main/java/org/bukkit/util/noise/SimplexNoiseGenerator.java b/src/main/java/org/bukkit/util/noise/SimplexNoiseGenerator.java
new file mode 100644
index 00000000..c5e5781c
--- /dev/null
+++ b/src/main/java/org/bukkit/util/noise/SimplexNoiseGenerator.java
@@ -0,0 +1,513 @@
+package org.bukkit.util.noise;
+
+import java.util.Random;
+import org.bukkit.World;
+
+/**
+ * Generates simplex-based noise.
+ *
+ * This is a modified version of the freely published version in the paper by
+ * Stefan Gustavson at http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
+ */
+public class SimplexNoiseGenerator extends PerlinNoiseGenerator {
+    protected static final double SQRT_3 = Math.sqrt(3);
+    protected static final double SQRT_5 = Math.sqrt(5);
+    protected static final double F2 = 0.5 * (SQRT_3 - 1);
+    protected static final double G2 = (3 - SQRT_3) / 6;
+    protected static final double G22 = G2 * 2.0 - 1;
+    protected static final double F3 = 1.0 / 3.0;
+    protected static final double G3 = 1.0 / 6.0;
+    protected static final double F4 = (SQRT_5 - 1.0) / 4.0;
+    protected static final double G4 = (5.0 - SQRT_5) / 20.0;
+    protected static final double G42 = G4 * 2.0;
+    protected static final double G43 = G4 * 3.0;
+    protected static final double G44 = G4 * 4.0 - 1.0;
+    protected static final int grad4[][] = {{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}};
+    protected static final int simplex[][] = {
+        {0, 1, 2, 3}, {0, 1, 3, 2}, {0, 0, 0, 0}, {0, 2, 3, 1}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {1, 2, 3, 0},
+        {0, 2, 1, 3}, {0, 0, 0, 0}, {0, 3, 1, 2}, {0, 3, 2, 1}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {1, 3, 2, 0},
+        {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0},
+        {1, 2, 0, 3}, {0, 0, 0, 0}, {1, 3, 0, 2}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {2, 3, 0, 1}, {2, 3, 1, 0},
+        {1, 0, 2, 3}, {1, 0, 3, 2}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {2, 0, 3, 1}, {0, 0, 0, 0}, {2, 1, 3, 0},
+        {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0},
+        {2, 0, 1, 3}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {3, 0, 1, 2}, {3, 0, 2, 1}, {0, 0, 0, 0}, {3, 1, 2, 0},
+        {2, 1, 0, 3}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {3, 1, 0, 2}, {0, 0, 0, 0}, {3, 2, 0, 1}, {3, 2, 1, 0}};
+    protected static double offsetW;
+    private static final SimplexNoiseGenerator instance = new SimplexNoiseGenerator();
+
+    protected SimplexNoiseGenerator() {
+        super();
+    }
+
+    /**
+     * Creates a seeded simplex noise generator for the given world
+     *
+     * @param world World to construct this generator for
+     */
+    public SimplexNoiseGenerator(World world) {
+        this(new Random(world.getSeed()));
+    }
+
+    /**
+     * Creates a seeded simplex noise generator for the given seed
+     *
+     * @param seed Seed to construct this generator for
+     */
+    public SimplexNoiseGenerator(long seed) {
+        this(new Random(seed));
+    }
+
+    /**
+     * Creates a seeded simplex noise generator with the given Random
+     *
+     * @param rand Random to construct with
+     */
+    public SimplexNoiseGenerator(Random rand) {
+        super(rand);
+        offsetW = rand.nextDouble() * 256;
+    }
+
+    protected static double dot(int g[], double x, double y) {
+        return g[0] * x + g[1] * y;
+    }
+
+    protected static double dot(int g[], double x, double y, double z) {
+        return g[0] * x + g[1] * y + g[2] * z;
+    }
+
+    protected static double dot(int g[], double x, double y, double z, double w) {
+        return g[0] * x + g[1] * y + g[2] * z + g[3] * w;
+    }
+
+    /**
+     * Computes and returns the 1D unseeded simplex noise for the given coordinates in 1D space
+     *
+     * @param xin X coordinate
+     * @return Noise at given location, from range -1 to 1
+     */
+    public static double getNoise(double xin) {
+        return instance.noise(xin);
+    }
+
+    /**
+     * Computes and returns the 2D unseeded simplex noise for the given coordinates in 2D space
+     *
+     * @param xin X coordinate
+     * @param yin Y coordinate
+     * @return Noise at given location, from range -1 to 1
+     */
+    public static double getNoise(double xin, double yin) {
+        return instance.noise(xin, yin);
+    }
+
+    /**
+     * Computes and returns the 3D unseeded simplex noise for the given coordinates in 3D space
+     *
+     * @param xin X coordinate
+     * @param yin Y coordinate
+     * @param zin Z coordinate
+     * @return Noise at given location, from range -1 to 1
+     */
+    public static double getNoise(double xin, double yin, double zin) {
+        return instance.noise(xin, yin, zin);
+    }
+
+    /**
+     * Computes and returns the 4D simplex noise for the given coordinates in 4D space
+     *
+     * @param x X coordinate
+     * @param y Y coordinate
+     * @param z Z coordinate
+     * @param w W coordinate
+     * @return Noise at given location, from range -1 to 1
+     */
+    public static double getNoise(double x, double y, double z, double w) {
+        return instance.noise(x, y, z, w);
+    }
+
+    @Override
+    public double noise(double xin, double yin, double zin) {
+        xin += offsetX;
+        yin += offsetY;
+        zin += offsetZ;
+
+        double n0, n1, n2, n3; // Noise contributions from the four corners
+
+        // Skew the input space to determine which simplex cell we're in
+        double s = (xin + yin + zin) * F3; // Very nice and simple skew factor for 3D
+        int i = floor(xin + s);
+        int j = floor(yin + s);
+        int k = floor(zin + s);
+        double t = (i + j + k) * G3;
+        double X0 = i - t; // Unskew the cell origin back to (x,y,z) space
+        double Y0 = j - t;
+        double Z0 = k - t;
+        double x0 = xin - X0; // The x,y,z distances from the cell origin
+        double y0 = yin - Y0;
+        double z0 = zin - Z0;
+
+        // For the 3D case, the simplex shape is a slightly irregular tetrahedron.
+
+        // Determine which simplex we are in.
+        int i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords
+        int 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.
+        double x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
+        double y1 = y0 - j1 + G3;
+        double z1 = z0 - k1 + G3;
+        double x2 = x0 - i2 + 2.0 * G3; // Offsets for third corner in (x,y,z) coords
+        double y2 = y0 - j2 + 2.0 * G3;
+        double z2 = z0 - k2 + 2.0 * G3;
+        double x3 = x0 - 1.0 + 3.0 * G3; // Offsets for last corner in (x,y,z) coords
+        double y3 = y0 - 1.0 + 3.0 * G3;
+        double z3 = z0 - 1.0 + 3.0 * G3;
+
+        // Work out the hashed gradient indices of the four simplex corners
+        int ii = i & 255;
+        int jj = j & 255;
+        int kk = k & 255;
+        int gi0 = perm[ii + perm[jj + perm[kk]]] % 12;
+        int gi1 = perm[ii + i1 + perm[jj + j1 + perm[kk + k1]]] % 12;
+        int gi2 = perm[ii + i2 + perm[jj + j2 + perm[kk + k2]]] % 12;
+        int gi3 = perm[ii + 1 + perm[jj + 1 + perm[kk + 1]]] % 12;
+
+        // Calculate the contribution from the four corners
+        double t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0;
+        if (t0 < 0) {
+            n0 = 0.0;
+        } else {
+            t0 *= t0;
+            n0 = t0 * t0 * dot(grad3[gi0], x0, y0, z0);
+        }
+
+        double t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1;
+        if (t1 < 0) {
+            n1 = 0.0;
+        } else {
+            t1 *= t1;
+            n1 = t1 * t1 * dot(grad3[gi1], x1, y1, z1);
+        }
+
+        double t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2;
+        if (t2 < 0) {
+            n2 = 0.0;
+        } else {
+            t2 *= t2;
+            n2 = t2 * t2 * dot(grad3[gi2], x2, y2, z2);
+        }
+
+        double t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3;
+        if (t3 < 0) {
+            n3 = 0.0;
+        } else {
+            t3 *= t3;
+            n3 = t3 * t3 * dot(grad3[gi3], x3, y3, 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);
+    }
+
+    @Override
+    public double noise(double xin, double yin) {
+        xin += offsetX;
+        yin += offsetY;
+
+        double n0, n1, n2; // Noise contributions from the three corners
+
+        // Skew the input space to determine which simplex cell we're in
+        double s = (xin + yin) * F2; // Hairy factor for 2D
+        int i = floor(xin + s);
+        int j = floor(yin + s);
+        double t = (i + j) * G2;
+        double X0 = i - t; // Unskew the cell origin back to (x,y) space
+        double Y0 = j - t;
+        double x0 = xin - X0; // The x,y distances from the cell origin
+        double y0 = yin - Y0;
+
+        // For the 2D case, the simplex shape is an equilateral triangle.
+
+        // Determine which simplex we are in.
+        int i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords
+        if (x0 > y0) {
+            i1 = 1;
+            j1 = 0;
+        } // lower triangle, XY order: (0,0)->(1,0)->(1,1)
+        else {
+            i1 = 0;
+            j1 = 1;
+        } // upper triangle, YX order: (0,0)->(0,1)->(1,1)
+
+        // A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
+        // a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
+        // c = (3-sqrt(3))/6
+
+        double x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
+        double y1 = y0 - j1 + G2;
+        double x2 = x0 + G22; // Offsets for last corner in (x,y) unskewed coords
+        double y2 = y0 + G22;
+
+        // Work out the hashed gradient indices of the three simplex corners
+        int ii = i & 255;
+        int jj = j & 255;
+        int gi0 = perm[ii + perm[jj]] % 12;
+        int gi1 = perm[ii + i1 + perm[jj + j1]] % 12;
+        int gi2 = perm[ii + 1 + perm[jj + 1]] % 12;
+
+        // Calculate the contribution from the three corners
+        double t0 = 0.5 - x0 * x0 - y0 * y0;
+        if (t0 < 0) {
+            n0 = 0.0;
+        } else {
+            t0 *= t0;
+            n0 = t0 * t0 * dot(grad3[gi0], x0, y0); // (x,y) of grad3 used for 2D gradient
+        }
+
+        double t1 = 0.5 - x1 * x1 - y1 * y1;
+        if (t1 < 0) {
+            n1 = 0.0;
+        } else {
+            t1 *= t1;
+            n1 = t1 * t1 * dot(grad3[gi1], x1, y1);
+        }
+
+        double t2 = 0.5 - x2 * x2 - y2 * y2;
+        if (t2 < 0) {
+            n2 = 0.0;
+        } else {
+            t2 *= t2;
+            n2 = t2 * t2 * dot(grad3[gi2], x2, y2);
+        }
+
+        // Add contributions from each corner to get the final noise value.
+        // The result is scaled to return values in the interval [-1,1].
+        return 70.0 * (n0 + n1 + n2);
+    }
+
+    /**
+     * Computes and returns the 4D simplex noise for the given coordinates in 4D space
+     *
+     * @param xin X coordinate
+     * @param yin Y coordinate
+     * @param zin Z coordinate
+     * @param win W coordinate
+     * @return Noise at given location, from range -1 to 1
+     */
+    public double noise(double x, double y, double z, double w) {
+        x += offsetX;
+        y += offsetY;
+        z += offsetZ;
+        w += offsetW;
+
+        double n0, n1, n2, n3, n4; // Noise contributions from the five corners
+
+        // Skew the (x,y,z,w) space to determine which cell of 24 simplices we're in
+        double s = (x + y + z + w) * F4; // Factor for 4D skewing
+        int i = floor(x + s);
+        int j = floor(y + s);
+        int k = floor(z + s);
+        int l = floor(w + s);
+
+        double t = (i + j + k + l) * G4; // Factor for 4D unskewing
+        double X0 = i - t; // Unskew the cell origin back to (x,y,z,w) space
+        double Y0 = j - t;
+        double Z0 = k - t;
+        double W0 = l - t;
+        double x0 = x - X0; // The x,y,z,w distances from the cell origin
+        double y0 = y - Y0;
+        double z0 = z - Z0;
+        double w0 = w - W0;
+
+        // For the 4D case, the simplex is a 4D shape I won't even try to describe.
+        // To find out which of the 24 possible simplices we're in, we need to
+        // determine the magnitude ordering of x0, y0, z0 and w0.
+        // The method below is a good way of finding the ordering of x,y,z,w and
+        // then find the correct traversal order for the simplex we’re in.
+        // First, six pair-wise comparisons are performed between each possible pair
+        // of the four coordinates, and the results are used to add up binary bits
+        // for an integer index.
+        int c1 = (x0 > y0) ? 32 : 0;
+        int c2 = (x0 > z0) ? 16 : 0;
+        int c3 = (y0 > z0) ? 8 : 0;
+        int c4 = (x0 > w0) ? 4 : 0;
+        int c5 = (y0 > w0) ? 2 : 0;
+        int c6 = (z0 > w0) ? 1 : 0;
+        int c = c1 + c2 + c3 + c4 + c5 + c6;
+        int i1, j1, k1, l1; // The integer offsets for the second simplex corner
+        int i2, j2, k2, l2; // The integer offsets for the third simplex corner
+        int i3, j3, k3, l3; // The integer offsets for the fourth simplex corner
+
+        // simplex[c] is a 4-vector with the numbers 0, 1, 2 and 3 in some order.
+        // Many values of c will never occur, since e.g. x>y>z>w makes x<z, y<w and x<w
+        // impossible. Only the 24 indices which have non-zero entries make any sense.
+        // We use a thresholding to set the coordinates in turn from the largest magnitude.
+
+        // The number 3 in the "simplex" array is at the position of the largest coordinate.
+        i1 = simplex[c][0] >= 3 ? 1 : 0;
+        j1 = simplex[c][1] >= 3 ? 1 : 0;
+        k1 = simplex[c][2] >= 3 ? 1 : 0;
+        l1 = simplex[c][3] >= 3 ? 1 : 0;
+
+        // The number 2 in the "simplex" array is at the second largest coordinate.
+        i2 = simplex[c][0] >= 2 ? 1 : 0;
+        j2 = simplex[c][1] >= 2 ? 1 : 0;
+        k2 = simplex[c][2] >= 2 ? 1 : 0;
+        l2 = simplex[c][3] >= 2 ? 1 : 0;
+
+        // The number 1 in the "simplex" array is at the second smallest coordinate.
+        i3 = simplex[c][0] >= 1 ? 1 : 0;
+        j3 = simplex[c][1] >= 1 ? 1 : 0;
+        k3 = simplex[c][2] >= 1 ? 1 : 0;
+        l3 = simplex[c][3] >= 1 ? 1 : 0;
+
+        // The fifth corner has all coordinate offsets = 1, so no need to look that up.
+
+        double x1 = x0 - i1 + G4; // Offsets for second corner in (x,y,z,w) coords
+        double y1 = y0 - j1 + G4;
+        double z1 = z0 - k1 + G4;
+        double w1 = w0 - l1 + G4;
+
+        double x2 = x0 - i2 + G42; // Offsets for third corner in (x,y,z,w) coords
+        double y2 = y0 - j2 + G42;
+        double z2 = z0 - k2 + G42;
+        double w2 = w0 - l2 + G42;
+
+        double x3 = x0 - i3 + G43; // Offsets for fourth corner in (x,y,z,w) coords
+        double y3 = y0 - j3 + G43;
+        double z3 = z0 - k3 + G43;
+        double w3 = w0 - l3 + G43;
+
+        double x4 = x0 + G44; // Offsets for last corner in (x,y,z,w) coords
+        double y4 = y0 + G44;
+        double z4 = z0 + G44;
+        double w4 = w0 + G44;
+
+        // Work out the hashed gradient indices of the five simplex corners
+        int ii = i & 255;
+        int jj = j & 255;
+        int kk = k & 255;
+        int ll = l & 255;
+
+        int gi0 = perm[ii + perm[jj + perm[kk + perm[ll]]]] % 32;
+        int gi1 = perm[ii + i1 + perm[jj + j1 + perm[kk + k1 + perm[ll + l1]]]] % 32;
+        int gi2 = perm[ii + i2 + perm[jj + j2 + perm[kk + k2 + perm[ll + l2]]]] % 32;
+        int gi3 = perm[ii + i3 + perm[jj + j3 + perm[kk + k3 + perm[ll + l3]]]] % 32;
+        int gi4 = perm[ii + 1 + perm[jj + 1 + perm[kk + 1 + perm[ll + 1]]]] % 32;
+
+        // Calculate the contribution from the five corners
+        double t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0 - w0 * w0;
+        if (t0 < 0) {
+            n0 = 0.0;
+        } else {
+            t0 *= t0;
+            n0 = t0 * t0 * dot(grad4[gi0], x0, y0, z0, w0);
+        }
+
+        double t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1 - w1 * w1;
+        if (t1 < 0) {
+            n1 = 0.0;
+        } else {
+            t1 *= t1;
+            n1 = t1 * t1 * dot(grad4[gi1], x1, y1, z1, w1);
+        }
+
+        double t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2 - w2 * w2;
+        if (t2 < 0) {
+            n2 = 0.0;
+        } else {
+            t2 *= t2;
+            n2 = t2 * t2 * dot(grad4[gi2], x2, y2, z2, w2);
+        }
+
+        double t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3 - w3 * w3;
+        if (t3 < 0) {
+            n3 = 0.0;
+        } else {
+            t3 *= t3;
+            n3 = t3 * t3 * dot(grad4[gi3], x3, y3, z3, w3);
+        }
+
+        double t4 = 0.6 - x4 * x4 - y4 * y4 - z4 * z4 - w4 * w4;
+        if (t4 < 0) {
+            n4 = 0.0;
+        } else {
+            t4 *= t4;
+            n4 = t4 * t4 * dot(grad4[gi4], x4, y4, z4, w4);
+        }
+
+        // Sum up and scale the result to cover the range [-1,1]
+        return 27.0 * (n0 + n1 + n2 + n3 + n4);
+    }
+
+    /**
+     * Gets the singleton unseeded instance of this generator
+     *
+     * @return Singleton
+     */
+    public static SimplexNoiseGenerator getInstance() {
+        return instance;
+    }
+}