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https://github.com/VolmitSoftware/Iris.git
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377 lines
8.7 KiB
Java
377 lines
8.7 KiB
Java
package com.volmit.iris.noise;
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import java.util.Random;
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/**
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* A speed-improved simplex noise algorithm.
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*
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* <p>
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* Based on example code by Stefan Gustavson (stegu@itn.liu.se). Optimisations
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* by Peter Eastman (peastman@drizzle.stanford.edu). Better rank ordering method
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* by Stefan Gustavson in 2012.
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*
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* <p>
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* This could be sped up even further, but it's useful as is.
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*/
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public class SNG extends PerlinNoise
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{
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protected static final double SQRT_3 = 1.7320508075688772; // Math.sqrt(3)
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protected static final double F2 = 0.5 * (SQRT_3 - 1);
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protected static final double G2 = (3 - SQRT_3) / 6;
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protected static final double G22 = G2 * 2.0 - 1;
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protected static final double F3 = 1.0 / 3.0;
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protected static final double G3 = 1.0 / 6.0;
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protected static final double G32 = G3 * 2.0;
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protected static final double G33 = G3 * 3.0 - 1.0;
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private static Grad[] grad3 = {new Grad(1, 1, 0), new Grad(-1, 1, 0), new Grad(1, -1, 0), new Grad(-1, -1, 0), new Grad(1, 0, 1), new Grad(-1, 0, 1), new Grad(1, 0, -1), new Grad(-1, 0, -1), new Grad(0, 1, 1), new Grad(0, -1, 1), new Grad(0, 1, -1), new Grad(0, -1, -1)};
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protected final int[] permMod12 = new int[512];
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/**
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* Creates a simplex noise generator.
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*
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* @param rand
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* the PRNG to use
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*/
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public SNG(Random rand)
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{
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super(rand);
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for(int i = 0; i < 512; i++)
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{
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permMod12[i] = perm[i] % 12;
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}
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}
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public static int floor(double x)
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{
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return x > 0 ? (int) x : (int) x - 1;
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}
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protected static double dot(Grad g, double x, double y)
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{
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return g.x * x + g.y * y;
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}
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protected static double dot(Grad g, double x, double y, double z)
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{
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return g.x * x + g.y * y + g.z * z;
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}
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@Override
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protected double[] get2dNoise(double[] noise, double x, double z, int sizeX, int sizeY, double scaleX, double scaleY, double amplitude)
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{
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int index = 0;
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for(int i = 0; i < sizeY; i++)
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{
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double zin = offsetY + (z + i) * scaleY;
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for(int j = 0; j < sizeX; j++)
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{
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double xin = offsetX + (x + j) * scaleX;
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noise[index++] += simplex2D(xin, zin) * amplitude;
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}
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}
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return noise;
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}
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@Override
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protected double[] get3dNoise(double[] noise, double x, double y, double z, int sizeX, int sizeY, int sizeZ, double scaleX, double scaleY, double scaleZ, double amplitude)
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{
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int index = 0;
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for(int i = 0; i < sizeZ; i++)
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{
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double zin = offsetZ + (z + i) * scaleZ;
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for(int j = 0; j < sizeX; j++)
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{
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double xin = offsetX + (x + j) * scaleX;
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for(int k = 0; k < sizeY; k++)
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{
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double yin = offsetY + (y + k) * scaleY;
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noise[index++] += simplex3D(xin, yin, zin) * amplitude;
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}
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}
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}
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return noise;
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}
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@Override
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public double noise(double xin, double yin)
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{
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xin += offsetX;
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yin += offsetY;
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return simplex2D(xin, yin);
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}
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@Override
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public double noise(double xin, double yin, double zin)
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{
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xin += offsetX;
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yin += offsetY;
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zin += offsetZ;
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return simplex3D(xin, yin, zin);
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}
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private double simplex2D(double xin, double yin)
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{
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// Skew the input space to determine which simplex cell we're in
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double s = (xin + yin) * F2; // Hairy factor for 2D
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int i = floor(xin + s);
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int j = floor(yin + s);
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double t = (i + j) * G2;
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double dx0 = i - t; // Unskew the cell origin back to (x,y) space
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double dy0 = j - t;
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double x0 = xin - dx0; // The x,y distances from the cell origin
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double y0 = yin - dy0;
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// For the 2D case, the simplex shape is an equilateral triangle.
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// Determine which simplex we are in.
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int i1; // Offsets for second (middle) corner of simplex in (i,j) coords
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int j1;
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if(x0 > y0)
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{
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i1 = 1; // lower triangle, XY order: (0,0)->(1,0)->(1,1)
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j1 = 0;
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}
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else
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{
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i1 = 0; // upper triangle, YX order: (0,0)->(0,1)->(1,1)
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j1 = 1;
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}
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// A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
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// a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
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// c = (3-sqrt(3))/6
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double x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
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double y1 = y0 - j1 + G2;
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double x2 = x0 + G22; // Offsets for last corner in (x,y) unskewed coords
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double y2 = y0 + G22;
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// Work out the hashed gradient indices of the three simplex corners
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int ii = i & 255;
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int jj = j & 255;
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int gi0 = permMod12[ii + perm[jj]];
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int gi1 = permMod12[ii + i1 + perm[jj + j1]];
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int gi2 = permMod12[ii + 1 + perm[jj + 1]];
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// Calculate the contribution from the three corners
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double t0 = 0.5 - x0 * x0 - y0 * y0;
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double n0;
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if(t0 < 0)
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{
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n0 = 0.0;
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}
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else
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{
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t0 *= t0;
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n0 = t0 * t0 * dot(grad3[gi0], x0, y0); // (x,y) of grad3 used for 2D gradient
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}
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double t1 = 0.5 - x1 * x1 - y1 * y1;
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double n1;
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if(t1 < 0)
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{
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n1 = 0.0;
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}
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else
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{
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t1 *= t1;
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n1 = t1 * t1 * dot(grad3[gi1], x1, y1);
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}
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double t2 = 0.5 - x2 * x2 - y2 * y2;
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double n2;
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if(t2 < 0)
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{
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n2 = 0.0;
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}
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else
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{
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t2 *= t2;
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n2 = t2 * t2 * dot(grad3[gi2], x2, y2);
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}
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// Add contributions from each corner to get the final noise value.
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// The result is scaled to return values in the interval [-1,1].
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return 70.0 * (n0 + n1 + n2);
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}
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private double simplex3D(double xin, double yin, double zin)
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{
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// Skew the input space to determine which simplex cell we're in
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double s = (xin + yin + zin) * F3; // Very nice and simple skew factor for 3D
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int i = floor(xin + s);
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int j = floor(yin + s);
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int k = floor(zin + s);
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double t = (i + j + k) * G3;
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double dx0 = i - t; // Unskew the cell origin back to (x,y,z) space
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double dy0 = j - t;
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double dz0 = k - t;
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// For the 3D case, the simplex shape is a slightly irregular tetrahedron.
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int i1; // Offsets for second corner of simplex in (i,j,k) coords
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int j1;
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int k1;
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int i2; // Offsets for third corner of simplex in (i,j,k) coords
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int j2;
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int k2;
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double x0 = xin - dx0; // The x,y,z distances from the cell origin
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double y0 = yin - dy0;
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double z0 = zin - dz0;
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// Determine which simplex we are in
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if(x0 >= y0)
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{
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if(y0 >= z0)
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{
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i1 = 1; // X Y Z order
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j1 = 0;
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k1 = 0;
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i2 = 1;
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j2 = 1;
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k2 = 0;
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}
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else if(x0 >= z0)
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{
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i1 = 1; // X Z Y order
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j1 = 0;
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k1 = 0;
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i2 = 1;
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j2 = 0;
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k2 = 1;
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}
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else
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{
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i1 = 0; // Z X Y order
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j1 = 0;
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k1 = 1;
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i2 = 1;
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j2 = 0;
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k2 = 1;
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}
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}
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else
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{ // x0<y0
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if(y0 < z0)
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{
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i1 = 0; // Z Y X order
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j1 = 0;
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k1 = 1;
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i2 = 0;
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j2 = 1;
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k2 = 1;
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}
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else if(x0 < z0)
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{
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i1 = 0; // Y Z X order
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j1 = 1;
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k1 = 0;
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i2 = 0;
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j2 = 1;
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k2 = 1;
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}
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else
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{
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i1 = 0; // Y X Z order
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j1 = 1;
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k1 = 0;
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i2 = 1;
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j2 = 1;
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k2 = 0;
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}
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}
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// A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
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// a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
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// a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
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// c = 1/6.
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double x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
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double y1 = y0 - j1 + G3;
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double z1 = z0 - k1 + G3;
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double x2 = x0 - i2 + G32; // Offsets for third corner in (x,y,z) coords
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double y2 = y0 - j2 + G32;
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double z2 = z0 - k2 + G32;
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// Work out the hashed gradient indices of the four simplex corners
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int ii = i & 255;
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int jj = j & 255;
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int kk = k & 255;
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int gi0 = permMod12[ii + perm[jj + perm[kk]]];
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int gi1 = permMod12[ii + i1 + perm[jj + j1 + perm[kk + k1]]];
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int gi2 = permMod12[ii + i2 + perm[jj + j2 + perm[kk + k2]]];
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int gi3 = permMod12[ii + 1 + perm[jj + 1 + perm[kk + 1]]];
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// Calculate the contribution from the four corners
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double t0 = 0.5 - x0 * x0 - y0 * y0 - z0 * z0;
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double n0; // Noise contributions from the four corners
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if(t0 < 0)
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{
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n0 = 0.0;
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}
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else
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{
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t0 *= t0;
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n0 = t0 * t0 * dot(grad3[gi0], x0, y0, z0);
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}
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double t1 = 0.5 - x1 * x1 - y1 * y1 - z1 * z1;
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double n1;
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if(t1 < 0)
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{
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n1 = 0.0;
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}
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else
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{
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t1 *= t1;
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n1 = t1 * t1 * dot(grad3[gi1], x1, y1, z1);
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}
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double t2 = 0.5 - x2 * x2 - y2 * y2 - z2 * z2;
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double n2;
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if(t2 < 0)
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{
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n2 = 0.0;
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}
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else
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{
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t2 *= t2;
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n2 = t2 * t2 * dot(grad3[gi2], x2, y2, z2);
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}
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double x3 = x0 + G33; // Offsets for last corner in (x,y,z) coords
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double y3 = y0 + G33;
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double z3 = z0 + G33;
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double t3 = 0.5 - x3 * x3 - y3 * y3 - z3 * z3;
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double n3;
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if(t3 < 0)
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{
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n3 = 0.0;
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}
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else
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{
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t3 *= t3;
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n3 = t3 * t3 * dot(grad3[gi3], x3, y3, z3);
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}
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// Add contributions from each corner to get the final noise value.
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// The result is scaled to stay just inside [-1,1]
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return 32.0 * (n0 + n1 + n2 + n3);
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}
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// Inner class to speed up gradient computations
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// (array access is a lot slower than member access)
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private static class Grad
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{
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public double x;
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public double y;
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public double z;
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Grad(double x, double y, double z)
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{
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this.x = x;
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this.y = y;
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this.z = z;
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}
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}
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} |