SimplexNoise

package com.hypixel.hytale.procedurallib.logic;

import com.hypixel.hytale.procedurallib.NoiseFunction;
import javax.annotation.Nonnull;

public class SimplexNoise implements NoiseFunction {
   public static final SimplexNoise INSTANCE = new SimplexNoise();
   private static final double F2 = 0.5;
   private static final double P1_F2 = -0.5;
   private static final double G2 = 0.25;
   private static final double F3 = 0.3333333333333333;
   private static final double G3 = 0.16666666666666666;
   private static final double G33 = -0.5;

   private SimplexNoise() {
   }

   @Override
   public double get(int seed, int offsetSeed, double x, double y) {
      double t = (x + y) * 0.5;
      int i = GeneralNoise.fastFloor(x + t);
      int j = GeneralNoise.fastFloor(y + t);
      t = (double)(i + j) * 0.25;
      double X0 = (double)i - t;
      double Y0 = (double)j - t;
      double x0 = x - X0;
      double y0 = y - Y0;
      int i1;
      int j1;
      if (x0 > y0) {
         i1 = 1;
         j1 = 0;
      } else {
         i1 = 0;
         j1 = 1;
      }

      t = 0.5 - x0 * x0 - y0 * y0;
      double n0;
      if (t < 0.0) {
         n0 = 0.0;
      } else {
         t *= t;
         n0 = t * t * GeneralNoise.gradCoord2D(offsetSeed, i, j, x0, y0);
      }

      double x1 = x0 - (double)i1 + 0.25;
      double y1 = y0 - (double)j1 + 0.25;
      t = 0.5 - x1 * x1 - y1 * y1;
      double n1;
      if (t < 0.0) {
         n1 = 0.0;
      } else {
         t *= t;
         n1 = t * t * GeneralNoise.gradCoord2D(offsetSeed, i + i1, j + j1, x1, y1);
      }

      double x2 = x0 + -0.5;
      double y2 = y0 + -0.5;
      t = 0.5 - x2 * x2 - y2 * y2;
      double n2;
      if (t < 0.0) {
         n2 = 0.0;
      } else {
         t *= t;
         n2 = t * t * GeneralNoise.gradCoord2D(offsetSeed, i + 1, j + 1, x2, y2);
      }

      return 50.0 * (n0 + n1 + n2);
   }

   @Override
   public double get(int seed, int offsetSeed, double x, double y, double z) {
      double t = (x + y + z) * 0.3333333333333333;
      int i = GeneralNoise.fastFloor(x + t);
      int j = GeneralNoise.fastFloor(y + t);
      int k = GeneralNoise.fastFloor(z + t);
      t = (double)(i + j + k) * 0.16666666666666666;
      double x0 = x - ((double)i - t);
      double y0 = y - ((double)j - t);
      double z0 = z - ((double)k - t);
      int i1;
      int j1;
      int k1;
      int i2;
      int j2;
      int k2;
      if (x0 >= y0) {
         if (y0 >= z0) {
            i1 = 1;
            j1 = 0;
            k1 = 0;
            i2 = 1;
            j2 = 1;
            k2 = 0;
         } else if (x0 >= z0) {
            i1 = 1;
            j1 = 0;
            k1 = 0;
            i2 = 1;
            j2 = 0;
            k2 = 1;
         } else {
            i1 = 0;
            j1 = 0;
            k1 = 1;
            i2 = 1;
            j2 = 0;
            k2 = 1;
         }
      } else if (y0 < z0) {
         i1 = 0;
         j1 = 0;
         k1 = 1;
         i2 = 0;
         j2 = 1;
         k2 = 1;
      } else if (x0 < z0) {
         i1 = 0;
         j1 = 1;
         k1 = 0;
         i2 = 0;
         j2 = 1;
         k2 = 1;
      } else {
         i1 = 0;
         j1 = 1;
         k1 = 0;
         i2 = 1;
         j2 = 1;
         k2 = 0;
      }

      double x1 = x0 - (double)i1 + 0.16666666666666666;
      double y1 = y0 - (double)j1 + 0.16666666666666666;
      double z1 = z0 - (double)k1 + 0.16666666666666666;
      double x2 = x0 - (double)i2 + 0.3333333333333333;
      double y2 = y0 - (double)j2 + 0.3333333333333333;
      double z2 = z0 - (double)k2 + 0.3333333333333333;
      double x3 = x0 + -0.5;
      double y3 = y0 + -0.5;
      double z3 = z0 + -0.5;
      t = 0.6 - x0 * x0 - y0 * y0 - z0 * z0;
      double n0;
      if (t < 0.0) {
         n0 = 0.0;
      } else {
         t *= t;
         n0 = t * t * GeneralNoise.gradCoord3D(offsetSeed, i, j, k, x0, y0, z0);
      }

      t = 0.6 - x1 * x1 - y1 * y1 - z1 * z1;
      double n1;
      if (t < 0.0) {
         n1 = 0.0;
      } else {
         t *= t;
         n1 = t * t * GeneralNoise.gradCoord3D(offsetSeed, i + i1, j + j1, k + k1, x1, y1, z1);
      }

      t = 0.6 - x2 * x2 - y2 * y2 - z2 * z2;
      double n2;
      if (t < 0.0) {
         n2 = 0.0;
      } else {
         t *= t;
         n2 = t * t * GeneralNoise.gradCoord3D(offsetSeed, i + i2, j + j2, k + k2, x2, y2, z2);
      }

      t = 0.6 - x3 * x3 - y3 * y3 - z3 * z3;
      double n3;
      if (t < 0.0) {
         n3 = 0.0;
      } else {
         t *= t;
         n3 = t * t * GeneralNoise.gradCoord3D(offsetSeed, i + 1, j + 1, k + 1, x3, y3, z3);
      }

      return 32.0 * (n0 + n1 + n2 + n3);
   }

   @Nonnull
   @Override
   public String toString() {
      return "SimplexNoise{}";
   }
}