/*

Coherent noise function over 1, 2 or 3 dimensions

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 Inc. may be used to endorse or promote products derived from the Apple

 Software without specific prior written permission from Apple.  Except

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 The Apple Software is provided by Apple on an "AS IS" basis.  APPLE

 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

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 FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND

 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

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 (copyright Ken Perlin)

*/

#include <stdio.h>

#include <stdlib.h>

#include <math.h>

#include <OpenGL/gl.h>

#include "Noise3DTexture.h"

void init3DNoiseTexture(int texSize, GLubyte* texPtr);

void make3DNoiseTexture();

int Noise3DTexSize = 64;

GLubyte* Noise3DTexPtr;

#define MAXB 0x100

#define N 0x1000

#define NP 12   // 2^N

#define NM 0xfff

#define s_curve(t) ( t * t * (3. - 2. * t) )

#define lerp(t, a, b) ( a + t * (b - a) )

#define setup(i, b0, b1, r0, r1)\

        t = vec[i] + N;\

        b0 = ((int)t) & BM;\

        b1 = (b0+1) & BM;\

        r0 = t - (int)t;\

        r1 = r0 - 1.;

#define at2(rx, ry) ( rx * q[0] + ry * q[1] )

#define at3(rx, ry, rz) ( rx * q[0] + ry * q[1] + rz * q[2] )

static void initNoise();

static int p[MAXB + MAXB + 2];

static double g3[MAXB + MAXB + 2][3];

static double g2[MAXB + MAXB + 2][2];

static double g1[MAXB + MAXB + 2];

int start;

int B;

int BM;

void SetNoiseFrequency(int frequency)

{

    start = 1;

    B = frequency;

    BM = B-1;

}

double noise1(double arg)

{

    int bx0, bx1;

    double rx0, rx1, sx, t, u, v, vec[1];

    vec[0] = arg;

    if (start)

    {

        start = 0;

        initNoise();

    }

    setup(0, bx0, bx1, rx0, rx1);

    sx = s_curve(rx0);

    u = rx0 * g1[p[bx0]];

    v = rx1 * g1[p[bx1]];

    return(lerp(sx, u, v));

}

double noise2(double vec[2])

{

    int bx0, bx1, by0, by1, b00, b10, b01, b11;

    double rx0, rx1, ry0, ry1, *q, sx, sy, a, b, t, u, v;

    int i, j;

    if (start)

    {

        start = 0;

        initNoise();

    }

    setup(0, bx0, bx1, rx0, rx1);

    setup(1, by0, by1, ry0, ry1);

    i = p[bx0];

    j = p[bx1];

    b00 = p[i + by0];

    b10 = p[j + by0];

    b01 = p[i + by1];

    b11 = p[j + by1];

    sx = s_curve(rx0);

    sy = s_curve(ry0);

    q = g2[b00]; u = at2(rx0, ry0);

    q = g2[b10]; v = at2(rx1, ry0);

    a = lerp(sx, u, v);

    q = g2[b01]; u = at2(rx0, ry1);

    q = g2[b11]; v = at2(rx1, ry1);

    b = lerp(sx, u, v);

    return lerp(sy, a, b);

}

double noise3(double vec[3])

{

    int bx0, bx1, by0, by1, bz0, bz1, b00, b10, b01, b11;

    double rx0, rx1, ry0, ry1, rz0, rz1, *q, sy, sz, a, b, c, d, t, u, v;

    int i, j;

    if (start)

    {

        start = 0;

        initNoise();

    }

    setup(0, bx0, bx1, rx0, rx1);

    setup(1, by0, by1, ry0, ry1);

    setup(2, bz0, bz1, rz0, rz1);

    i = p[bx0];

    j = p[bx1];

    b00 = p[i + by0];

    b10 = p[j + by0];

    b01 = p[i + by1];

    b11 = p[j + by1];

    t  = s_curve(rx0);

    sy = s_curve(ry0);

    sz = s_curve(rz0);

    q = g3[b00 + bz0]; u = at3(rx0, ry0, rz0);

    q = g3[b10 + bz0]; v = at3(rx1, ry0, rz0);

    a = lerp(t, u, v);

    q = g3[b01 + bz0]; u = at3(rx0, ry1, rz0);

    q = g3[b11 + bz0]; v = at3(rx1, ry1, rz0);

    b = lerp(t, u, v);

    c = lerp(sy, a, b);

    q = g3[b00 + bz1]; u = at3(rx0, ry0, rz1);

    q = g3[b10 + bz1]; v = at3(rx1, ry0, rz1);

    a = lerp(t, u, v);

    q = g3[b01 + bz1]; u = at3(rx0, ry1, rz1);

    q = g3[b11 + bz1]; v = at3(rx1, ry1, rz1);

    b = lerp(t, u, v);

    d = lerp(sy, a, b);

    return lerp(sz, c, d);

}

void normalize2(double v[2])

{

    double s;

    s = sqrt(v[0] * v[0] + v[1] * v[1]);

    v[0] = v[0] / s;

    v[1] = v[1] / s;

}

void normalize3(double v[3])

{

    double s;

    s = sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);

    v[0] = v[0] / s;

    v[1] = v[1] / s;

    v[2] = v[2] / s;

}

void init3DNoiseTexture(int texSize, GLubyte* texPtr)

{

    glTexParameterf(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_REPEAT);

    glTexParameterf(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_REPEAT);

    glTexParameterf(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_REPEAT);

    glTexParameterf(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glTexParameterf(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

    glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA8, texSize, texSize, texSize, 0, GL_RGBA, GL_UNSIGNED_BYTE, texPtr);

    free(texPtr);

}

void initNoise()

{

    int i, j, k;

    srand(30757);

    for (i = 0; i < B; i++)

    {

        p[i] = i;

        g1[i] = (double)((rand() % (B + B)) - B) / B;

        for (j = 0; j < 2; j++)

            g2[i][j] = (double)((rand() % (B + B)) - B) / B;

        normalize2(g2[i]);

        for (j = 0; j < 3; j++)

            g3[i][j] = (double)((rand() % (B + B)) - B) / B;

        normalize3(g3[i]);

    }

    while (--i)

    {

        k = p[i];

        p[i] = p[j = rand() % B];

        p[j] = k;

    }

    for (i = 0; i < B + 2; i++)

    {

        p[B + i] = p[i];

        g1[B + i] = g1[i];

        for (j = 0; j < 2; j++)

            g2[B + i][j] = g2[i][j];

        for (j = 0; j < 3; j++)

            g3[B + i][j] = g3[i][j];

    }

}

// My harmonic summing functions - PDB

//

// In what follows "alpha" is the weight when the sum is formed.

// Typically it is 2, As this approaches 1 the function is noisier.

// "beta" is the harmonic scaling/spacing, typically 2.

//

double PerlinNoise1D(double x,double alpha,double beta,int n)

{

    int i;

    double val,sum = 0;

    double p,scale = 1;

    p = x;

    for (i = 0; i < n; i++)

    {

        val = noise1(p);

        sum += val / scale;

        scale *= alpha;

        p *= beta;

    }

    return(sum);

}

double PerlinNoise2D(double x, double y, double alpha, double beta, int n)

{

    int i;

    double val, sum = 0;

    double p[2], scale = 1;

    p[0] = x;

    p[1] = y;

    for (i = 0; i < n; i++)

    {

        val = noise2(p);

        sum += val / scale;

        scale *= alpha;

        p[0] *= beta;

        p[1] *= beta;

    }

    return(sum);

    }

double PerlinNoise3D(double x, double y, double z, double alpha, double beta, int n)

{

    int i;

    double val,sum = 0;

    double p[3],scale = 1;

    p[0] = x;

    p[1] = y;

    p[2] = z;

    for (i = 0; i < n; i++)

    {

        val = noise3(p);

        sum += val / scale;

        scale *= alpha;

        p[0] *= beta;

        p[1] *= beta;

        p[2] *= beta;

    }

    return(sum);

}

void make3DNoiseTexture()

{

    int f, i, j, k, inc;

    int startFrequency = 4;

    int numOctaves = 4;

    double ni[3];

    double inci, incj, inck;

    int frequency = startFrequency;

    GLubyte* ptr;

    double amp = 0.5;

    Noise3DTexPtr = (GLubyte*) malloc(Noise3DTexSize * Noise3DTexSize * Noise3DTexSize * 4);

    for (f = 0, inc = 0; f < numOctaves; ++f, frequency *= 2, ++inc, amp *= 0.5)

    {

        SetNoiseFrequency(frequency);

        ptr = Noise3DTexPtr;

        ni[0] = ni[1] = ni[2] = 0;

        inci = 1.0 / (Noise3DTexSize / frequency);

        for (i = 0; i < Noise3DTexSize; ++i, ni[0] += inci)

        {

            incj = 1.0 / (Noise3DTexSize / frequency);

            for (j = 0; j < Noise3DTexSize; ++j, ni[1] += incj)

            {

                inck = 1.0 / (Noise3DTexSize / frequency);

                for (k = 0; k < Noise3DTexSize; ++k, ni[2] += inck, ptr += 4)

                    *(ptr + inc) = (GLubyte) (((noise3(ni) + 1.0) * amp) * 128.0);

            }

        }

    }

}

void CreateNoise3D()

{

    make3DNoiseTexture();

    init3DNoiseTexture(Noise3DTexSize, Noise3DTexPtr);

}