package net.comcraft.src;

import java.util.Random;

/*
 * A speed-improved simplex noise algorithm for 2D, 3D and 4D in Java.
 *
 * Based on example code by Stefan Gustavson (stegu@itn.liu.se).
 * Optimisations by Peter Eastman (peastman@drizzle.stanford.edu).
 * Better rank ordering method by Stefan Gustavson in 2012.
 *
 * This could be speeded up even further, but it's useful as it is.
 *
 * Version 2012-03-09
 *
 * This code was placed in the public domain by its original author,
 * Stefan Gustavson. You may use it as you see fit, but
 * attribution is appreciated.
 *
 */
public class SimplexNoise {  // Simplex noise in 2D, 3D and 4D

    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)};
    private static Grad grad4[] = {new Grad(0, 1, 1, 1), new Grad(0, 1, 1, -1), new Grad(0, 1, -1, 1), new Grad(0, 1, -1, -1),
        new Grad(0, -1, 1, 1), new Grad(0, -1, 1, -1), new Grad(0, -1, -1, 1), new Grad(0, -1, -1, -1),
        new Grad(1, 0, 1, 1), new Grad(1, 0, 1, -1), new Grad(1, 0, -1, 1), new Grad(1, 0, -1, -1),
        new Grad(-1, 0, 1, 1), new Grad(-1, 0, 1, -1), new Grad(-1, 0, -1, 1), new Grad(-1, 0, -1, -1),
        new Grad(1, 1, 0, 1), new Grad(1, 1, 0, -1), new Grad(1, -1, 0, 1), new Grad(1, -1, 0, -1),
        new Grad(-1, 1, 0, 1), new Grad(-1, 1, 0, -1), new Grad(-1, -1, 0, 1), new Grad(-1, -1, 0, -1),
        new Grad(1, 1, 1, 0), new Grad(1, 1, -1, 0), new Grad(1, -1, 1, 0), new Grad(1, -1, -1, 0),
        new Grad(-1, 1, 1, 0), new Grad(-1, 1, -1, 0), new Grad(-1, -1, 1, 0), new Grad(-1, -1, -1, 0)};
    private short p[] = new short[256];
    // To remove the need for index wrapping, double the permutation table length
    private short perm[] = new short[512];
    private short permMod12[] = new short[512];
    // Skewing and unskewing factors for 2, 3, and 4 dimensions
    private static final double F2 = 0.5 * (Math.sqrt(3.0) - 1.0);
    private static final double G2 = (3.0 - Math.sqrt(3.0)) / 6.0;
    private static final double F3 = 1.0 / 3.0;
    private static final double G3 = 1.0 / 6.0;
    private static final double F4 = (Math.sqrt(5.0) - 1.0) / 4.0;
    private static final double G4 = (5.0 - Math.sqrt(5.0)) / 20.0;

    public SimplexNoise(Random random) {
        for (int i = 0; i < p.length; ++i) {
            p[i] = (short) random.nextInt(256);
        }

        for (int i = 0; i < 512; i++) {
            perm[i] = p[i & 255];
            permMod12[i] = (short) (perm[i] % 12);
        }
    }

    // This method is a *lot* faster than using (int)Math.floor(x)
    private static int fastfloor(double x) {
        int xi = (int) x;
        return x < xi ? xi - 1 : xi;
    }

    private static double dot(Grad g, double x, double y) {
        return g.x * x + g.y * y;
    }

    private static double dot(Grad g, double x, double y, double z) {
        return g.x * x + g.y * y + g.z * z;
    }

    private static double dot(Grad g, double x, double y, double z, double w) {
        return g.x * x + g.y * y + g.z * z + g.w * w;
    }

    public double noise2DAdvanced(double x, double y, double persistence, int octaves) {
        double total = 0;

        for (int i = 0; i < octaves; ++i) {
            double frequency = MathHelper.pow(2, i);
            double amplitude = MathHelper.pow(persistence, i);
            
            total += noise2D(x * frequency, y * frequency) * amplitude;
        }

        return total;
    }

    // 2D simplex noise
    public double noise2D(double xin, double yin) {
        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 = fastfloor(xin + s);
        int j = fastfloor(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 - 1.0 + 2.0 * G2; // Offsets for last corner in (x,y) unskewed coords
        double y2 = y0 - 1.0 + 2.0 * G2;
        // Work out the hashed gradient indices of the three simplex corners
        int ii = i & 255;
        int jj = j & 255;
        int gi0 = permMod12[ii + perm[jj]];
        int gi1 = permMod12[ii + i1 + perm[jj + j1]];
        int gi2 = permMod12[ii + 1 + perm[jj + 1]];
        // 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);
    }

    // 3D simplex noise
    public double noise3D(double xin, double yin, double zin) {
        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 = fastfloor(xin + s);
        int j = fastfloor(yin + s);
        int k = fastfloor(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 = permMod12[ii + perm[jj + perm[kk]]];
        int gi1 = permMod12[ii + i1 + perm[jj + j1 + perm[kk + k1]]];
        int gi2 = permMod12[ii + i2 + perm[jj + j2 + perm[kk + k2]]];
        int gi3 = permMod12[ii + 1 + perm[jj + 1 + perm[kk + 1]]];
        // 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);
    }

    // 4D simplex noise, better simplex rank ordering method 2012-03-09
    public double noise4D(double x, double y, double z, double w) {

        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 = fastfloor(x + s);
        int j = fastfloor(y + s);
        int k = fastfloor(z + s);
        int l = fastfloor(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.
        // Six pair-wise comparisons are performed between each possible pair
        // of the four coordinates, and the results are used to rank the numbers.
        int rankx = 0;
        int ranky = 0;
        int rankz = 0;
        int rankw = 0;
        if (x0 > y0) {
            rankx++;
        } else {
            ranky++;
        }
        if (x0 > z0) {
            rankx++;
        } else {
            rankz++;
        }
        if (x0 > w0) {
            rankx++;
        } else {
            rankw++;
        }
        if (y0 > z0) {
            ranky++;
        } else {
            rankz++;
        }
        if (y0 > w0) {
            ranky++;
        } else {
            rankw++;
        }
        if (z0 > w0) {
            rankz++;
        } else {
            rankw++;
        }
        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.
        // Rank 3 denotes the largest coordinate.
        i1 = rankx >= 3 ? 1 : 0;
        j1 = ranky >= 3 ? 1 : 0;
        k1 = rankz >= 3 ? 1 : 0;
        l1 = rankw >= 3 ? 1 : 0;
        // Rank 2 denotes the second largest coordinate.
        i2 = rankx >= 2 ? 1 : 0;
        j2 = ranky >= 2 ? 1 : 0;
        k2 = rankz >= 2 ? 1 : 0;
        l2 = rankw >= 2 ? 1 : 0;
        // Rank 1 denotes the second smallest coordinate.
        i3 = rankx >= 1 ? 1 : 0;
        j3 = ranky >= 1 ? 1 : 0;
        k3 = rankz >= 1 ? 1 : 0;
        l3 = rankw >= 1 ? 1 : 0;
        // The fifth corner has all coordinate offsets = 1, so no need to compute that.
        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 + 2.0 * G4; // Offsets for third corner in (x,y,z,w) coords
        double y2 = y0 - j2 + 2.0 * G4;
        double z2 = z0 - k2 + 2.0 * G4;
        double w2 = w0 - l2 + 2.0 * G4;
        double x3 = x0 - i3 + 3.0 * G4; // Offsets for fourth corner in (x,y,z,w) coords
        double y3 = y0 - j3 + 3.0 * G4;
        double z3 = z0 - k3 + 3.0 * G4;
        double w3 = w0 - l3 + 3.0 * G4;
        double x4 = x0 - 1.0 + 4.0 * G4; // Offsets for last corner in (x,y,z,w) coords
        double y4 = y0 - 1.0 + 4.0 * G4;
        double z4 = z0 - 1.0 + 4.0 * G4;
        double w4 = w0 - 1.0 + 4.0 * G4;
        // 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);
    }

    // Inner class to speed upp gradient computations
    // (array access is a lot slower than member access)
    private static class Grad {

        double x, y, z, w;

        Grad(double x, double y, double z) {
            this.x = x;
            this.y = y;
            this.z = z;
        }

        Grad(double x, double y, double z, double w) {
            this.x = x;
            this.y = y;
            this.z = z;
            this.w = w;
        }
    }
}