package com.voxel.engine.core.Noise;

/**
 * Simplex Noise in 2D, 3D and 4D. Based on the example code of this paper:
 * http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
 *
 * @author Stefan Gustavson, Linkping University, Sweden (stegu at itn dot liu
 *         dot se)
 *
 *         Slight optimizations & restructuring by
 * @author Karsten Schmidt (info at toxi dot co dot uk)
 *
 */
public class SimplexNoise {

    private static final double SQRT3 = Math.sqrt(3.0);

    private static final double SQRT5 = Math.sqrt(5.0);

    private static final double F2 = 0.5 * (SQRT3 - 1.0);
    private static final double G2 = (3.0 - SQRT3) / 6.0;
    private static final double G22 = G2 * 2.0 - 1.0;
    private static final double F3 = 1.0 / 3.0;
    private static final double G3 = 1.0 / 6.0;
    private static final double G32 = G3 * 2.0;
    private static final double G33 = G3 * 3.0 - 1.0;
    private static final double F4 = (SQRT5 - 1.0) / 4.0;
    private static final double G4 = (5.0 - SQRT5) / 20.0;
    private static final double G42 = G4 * 2.0;
    private static final double G43 = G4 * 2.0;
    private static final double G44 = G4 * 4.0 - 1.0;

    private 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 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}, {0, -1, -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}};

    private static final 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 };

    private static int perm[] = new int[0x200];
    static {
        for(int i = 0;i < 0x100;i++){
            perm[i] = p[i & 0xff];
        }
    }

    private 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 } };

    private static final 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;
    }

    private static double dot(int g[], double x, double y, double z){
        return g[0] * x + g[1] * y + g[2] * z;
    }

    private 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;
    }

    public static double noise(double x, double y){
        double n0, n1, n2;
        double s = (x + y) * F2;
        int i = fastFloor(x + s);
        int j = fastFloor(y + s);
        double t = (i + j) * G2;

        double x0 = x - (i - t);
        double y0 = y - ( i - t);

        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 + G22;
        double y2 = y0 + G22;

        int ii = i & 0xff;
        int jj = j & 0xff;

        double t0 = 0.5 - x0 * x0 - y0 * y0;
        if(t0 < 0){
            n0 = 0.0;
        }else{
            t0 *= t0;
            int gi0 = perm[ii + perm[jj]] % 12;
            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;
            int gi1 = perm[ii + i1 + perm[jj + j1]] % 12;
            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;
            int gi2 = perm[ii + 1 + perm[jj + 1]] % 12;
            n2 = t2 * t2 * dot(grad3[gi2], x2, y2);
        }
        return 70.0 * (n0 + n1 + n2);
    }

    public static double noise(double x, double y, double z){
        double n0, n1, n2, n3;
        double s = (x + y + z) * F3;

        int i = fastFloor(x + s);
        int j = fastFloor(y + s);
        int k = fastFloor(z + s);

        double t = (i + j + k) * G3;
        double x0 = x - (i - t);
        double y0 = y - (j - t);
        double z0 = z - (k - t);

        int i1, j1, k1;
        int i2, j2, k2;

        if(x0 >= y0){
            if(y0 >= z0){
                i1 = 1;
                j1 = 0;
                k1 = 0;
                i2 = 1;
                j2 = 1;
                k2 = 0;
            }else if(x0 >= z0){
                i1 = 0;
                j1 = 0;
                k1 = 1;
                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 = 1;
                k1 = 0;
                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 - i1 + G3;
        double y1 = y0 - j1 + G3;
        double z1 = z0 - k1 + G3;
        double x2 = x0 - i2 + G3;
        double y2 = y0 - j2 + G32;
        double z2 = z0 - k2 + G32;
        double x3 = x0 + G33;
        double y3 = y0 + G33;
        double z3 = z0 + G33;

        int ii = i & 0xff;
        int jj = j & 0xff;
        int kk = k & 0xff;

        double t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0;
        if(t0 < 0){
            n0 = 0.0;
        }else{
            t0 *= t0;
            int gi0 = perm[ii + perm[jj + perm[kk]]] % 12;
            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;
            int gi1 = perm[ii + i1 + perm[jj + j1 + perm[kk + k1]]] % 12;
            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;
            int gi2 = perm[ii + i2 + perm[jj + j2 + perm[kk + k2]]] % 12;
            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;
            int gi3 = perm[ii + 1 + perm[jj + 1 + perm[kk + 1]]] % 12;
            n3 = t3 * t3 * dot(grad3[gi3], x3, y3, z3);
        }

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

    public static double noise(double x, double y, double z, double w) {
        double n0, n1, n2, n3, n4;

        double s = (x + y + z + w) * F4;

        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;

        double x0 = x - (i - t);
        double y0 = y - (j - t);
        double z0 = z - (k - t);
        double w0 = w - (l - t);

        int c = 0;
        if (x0 > y0){
            c = 0x20;
        }
        if (x0 > z0){
            c |= 0x10;
        }
        if (y0 > z0){
            c |= 0x08;
        }
        if (x0 > w0){
            c |= 0x04;
        }
        if (y0 > w0){
            c |= 0x02;
        }
        if (z0 > w0){
            c |= 0x01;
        }

        int i1, j1, k1, l1;
        int i2, j2, k2, l2;
        int i3, j3, k3, l3;

        int[] sc = simplex[c];

        i1 = sc[0] >= 3 ? 1 : 0;
        j1 = sc[1] >= 3 ? 1 : 0;
        k1 = sc[2] >= 3 ? 1 : 0;
        l1 = sc[3] >= 3 ? 1 : 0;

        i2 = sc[0] >= 2 ? 1 : 0;
        j2 = sc[1] >= 2 ? 1 : 0;
        k2 = sc[2] >= 2 ? 1 : 0;
        l2 = sc[3] >= 2 ? 1 : 0;

        i3 = sc[0] >= 1 ? 1 : 0;
        j3 = sc[1] >= 1 ? 1 : 0;
        k3 = sc[2] >= 1 ? 1 : 0;
        l3 = sc[3] >= 1 ? 1 : 0;

        double x1 = x0 - i1 + G4;

        double y1 = y0 - j1 + G4;
        double z1 = z0 - k1 + G4;
        double w1 = w0 - l1 + G4;
        double x2 = x0 - i2 + G42;

        double y2 = y0 - j2 + G42;
        double z2 = z0 - k2 + G42;
        double w2 = w0 - l2 + G42;
        double x3 = x0 - i3 + G43;

        double y3 = y0 - j3 + G43;
        double z3 = z0 - k3 + G43;
        double w3 = w0 - l3 + G43;
        double x4 = x0 - 1.0 + G44;

        double y4 = y0 + G44;
        double z4 = z0 + G44;
        double w4 = w0 + G44;

        int ii = i & 255;
        int jj = j & 255;
        int kk = k & 255;
        int ll = l & 255;

        double t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0 - w0 * w0;
        if (t0 < 0){
            n0 = 0.0;
        }else {
            t0 *= t0;
            int gi0 = perm[ii + perm[jj + perm[kk + perm[ll]]]] % 32;
            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;
            int gi1 = perm[ii + i1
                    + perm[jj + j1 + perm[kk + k1 + perm[ll + l1]]]] % 32;
            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;
            int gi2 = perm[ii + i2
                    + perm[jj + j2 + perm[kk + k2 + perm[ll + l2]]]] % 32;
            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;
            int gi3 = perm[ii + i3
                    + perm[jj + j3 + perm[kk + k3 + perm[ll + l3]]]] % 32;
            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;
            int gi4 = perm[ii + 1 + perm[jj + 1 + perm[kk + 1 + perm[ll + 1]]]] % 32;
            n4 = t4 * t4 * dot(grad4[gi4], x4, y4, z4, w4);
        }

        return 27.0 * (n0 + n1 + n2 + n3 + n4);
    }
}