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- package net.buddat.dynamic.map.gen;
- import java.util.Random;
- public class SimplexNoise {
- private static 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 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};
- // To remove the need for index wrapping, double the permutation table length
- private static int perm[] = new int[512];
- static {
- for(int i = 0; i < 512; i++)
- perm[i] = p[i & 255];
- }
- // This method is a *lot* faster than using (int)Math.floor(x)
- private static int fastfloor(double x) {
- return x > 0 ? (int)x : (int)x - 1;
- }
- private static double dot(int g[], double x, double y) {
- return g[0] * x + g[1] * y;
- }
- // 2D simplex noise
- public static double noise(double xin, double yin) {
- double n0, n1, n2;
- final double F2 = 0.5 * (Math.sqrt(3.0) - 1.0);
- double s = (xin + yin) * F2;
- int i = fastfloor(xin + s);
- int j = fastfloor(yin + s);
- final double G2 = (3.0 - Math.sqrt(3.0)) / 6.0;
- double t = (i + j) * G2;
- double X0 = i - t;
- double Y0 = j - t;
- double x0 = xin - X0;
- double y0 = yin - Y0;
- int i1, j1;
- if (x0 > y0) {
- i1=1;
- j1=0;
- } else {
- i1 = 0;
- j1 = 1;
- }
- double x1 = x0 - i1 + G2;
- double y1 = y0 - j1 + G2;
- double x2 = x0 - 1.0 + 2.0 * G2;
- double y2 = y0 - 1.0 + 2.0 * G2;
- 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;
- 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);
- }
- 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);
- }
- return 70.0 * (n0 + n1 + n2);
- }
- public static void genGrad(long seed) {
- Random rnd = new Random(seed);
- for(int i = 0; i < 255; i++)
- p[i] = i;
- for(int i = 0; i < 255; i++) {
- int j = rnd.nextInt(255);
- int nSwap = p[i];
- p[i] = p[j];
- p[j] = nSwap;
- }
- for(int i = 0; i < 512; i++)
- perm[i] = p[i & 255];
- }
- }
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