/**
 * @file noise.h
 * @brief Perlin noise routines for procedural textures, etc
 *
 * $LicenseInfo:firstyear=2000&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#ifndef LL_NOISE_H
#define LL_NOISE_H

#include "llmath.h"

F32 turbulence2(F32 *v, F32 freq);
F32 turbulence3(float *v, float freq);
F32 clouds3(float *v, float freq);
F32 noise2(float *vec);
F32 noise3(float *vec);

inline F32 bias(F32 a, F32 b)
{
    return (F32)pow(a, (F32)(log(b) / log(0.5f)));
}

inline F32 gain(F32 a, F32 b)
{
    F32 p = (F32) (log(1.f - b) / log(0.5f));

    if (a < .001f)
        return 0.f;
    else if (a > .999f)
        return 1.f;
    if (a < 0.5f)
        return (F32)(pow(2 * a, p) / 2.f);
    else
        return (F32)(1.f - pow(2 * (1.f - a), p) / 2.f);
}

inline F32 turbulence2(F32 *v, F32 freq)
{
    F32 t, vec[2];

    for (t = 0.f ; freq >= 1.f ; freq *= 0.5f) {
        vec[0] = freq * v[0];
        vec[1] = freq * v[1];
        t += noise2(vec)/freq;
    }
    return t;
}

inline F32 turbulence3(F32 *v, F32 freq)
{
    F32 t, vec[3];

    for (t = 0.f ; freq >= 1.f ; freq *= 0.5f) {
        vec[0] = freq * v[0];
        vec[1] = freq * v[1];
        vec[2] = freq * v[2];
        t += noise3(vec)/freq;
//      t += fabs(noise3(vec)) / freq;              // Like snow - bubbly at low frequencies
//      t += sqrt(fabs(noise3(vec))) / freq;        // Better at low freq
//      t += (noise3(vec)*noise3(vec)) / freq;
    }
    return t;
}

inline F32 clouds3(F32 *v, F32 freq)
{
    F32 t, vec[3];

    for (t = 0.f ; freq >= 1.f ; freq *= 0.5f) {
        vec[0] = freq * v[0];
        vec[1] = freq * v[1];
        vec[2] = freq * v[2];
        //t += noise3(vec)/freq;
//      t += fabs(noise3(vec)) / freq;              // Like snow - bubbly at low frequencies
//      t += sqrt(fabs(noise3(vec))) / freq;        // Better at low freq
        t += (noise3(vec)*noise3(vec)) / freq;
    }
    return t;
}

/* noise functions over 1, 2, and 3 dimensions */

#define B 0x100
#define BM 0xff

#define N 0x1000
#define NF32 (4096.f)
#define NP 12   /* 2^N */
#define NM 0xfff

extern S32 p[B + B + 2];
extern F32 g3[B + B + 2][3];
extern F32 g2[B + B + 2][2];
extern F32 g1[B + B + 2];
extern S32 gNoiseStart;

static void init(void);

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

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

#define setup_noise(i,b0,b1,r0,r1)\
    t = vec[i] + N;\
    b0 = (lltrunc(t)) & BM;\
    b1 = (b0+1) & BM;\
    r0 = t - lltrunc(t);\
    r1 = r0 - 1.f;


inline void fast_setup(F32 vec, U8 &b0, U8 &b1, F32 &r0, F32 &r1)
{
    S32 t_S32;

    r1  = vec + NF32;
    t_S32 = lltrunc(r1);
    b0 = (U8)t_S32;
    b1 = b0 + 1;
    r0 = r1 - t_S32;
    r1 = r0 - 1.f;
}

inline F32 noise1(const F32 arg)
{
    int bx0, bx1;
    F32 rx0, rx1, sx, t, u, v, vec[1];

    vec[0] = arg;
    if (gNoiseStart) {
        gNoiseStart = 0;
        init();
    }

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

    sx = s_curve(rx0);

    u = rx0 * g1[ p[ bx0 ] ];
    v = rx1 * g1[ p[ bx1 ] ];

    return lerp_m(sx, u, v);
}

inline F32 fast_at2(F32 rx, F32 ry, F32 *q)
{
    return rx * (*q) + ry * (*(q + 1));
}



inline F32 fast_at3(F32 rx, F32 ry, F32 rz, F32 *q)
{
    return rx * (*q) + ry * (*(q + 1)) + rz * (*(q + 2));
}



inline F32 noise3(F32 *vec)
{
    U8 bx0, bx1, by0, by1, bz0, bz1;
    S32 b00, b10, b01, b11;
    F32 rx0, rx1, ry0, ry1, rz0, rz1, *q, sy, sz, a, b, c, d, t, u, v;
    S32 i, j;

    if (gNoiseStart) {
        gNoiseStart = 0;
        init();
    }

    fast_setup(*vec, bx0,bx1, rx0,rx1);
    fast_setup(*(vec + 1), by0,by1, ry0,ry1);
    fast_setup(*(vec + 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 = fast_at3(rx0,ry0,rz0,q);
    q = g3[ b10 + bz0 ];
    v = fast_at3(rx1,ry0,rz0,q);
    a = lerp_m(t, u, v);

    q = g3[ b01 + bz0 ];
    u = fast_at3(rx0,ry1,rz0,q);
    q = g3[ b11 + bz0 ];
    v = fast_at3(rx1,ry1,rz0,q);
    b = lerp_m(t, u, v);

    c = lerp_m(sy, a, b);

    q = g3[ b00 + bz1 ];
    u = fast_at3(rx0,ry0,rz1,q);
    q = g3[ b10 + bz1 ];
    v = fast_at3(rx1,ry0,rz1,q);
    a = lerp_m(t, u, v);

    q = g3[ b01 + bz1 ];
    u = fast_at3(rx0,ry1,rz1,q);
    q = g3[ b11 + bz1 ];
    v = fast_at3(rx1,ry1,rz1,q);
    b = lerp_m(t, u, v);

    d = lerp_m(sy, a, b);

    return lerp_m(sz, c, d);
}


/*
F32 noise3(F32 *vec)
{
    int bx0, bx1, by0, by1, bz0, bz1, b00, b10, b01, b11;
    F32 rx0, rx1, ry0, ry1, rz0, rz1, *q, sy, sz, a, b, c, d, t, u, v;
    S32 i, j;

    if (gNoiseStart) {
        gNoiseStart = 0;
        init();
    }

    setup_noise(0, bx0,bx1, rx0,rx1);
    setup_noise(1, by0,by1, ry0,ry1);
    setup_noise(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);

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

    q = g3[ b00 + bz0 ] ; u = at3(rx0,ry0,rz0);
    q = g3[ b10 + bz0 ] ; v = at3(rx1,ry0,rz0);
    a = lerp_m(t, u, v);

    q = g3[ b01 + bz0 ] ; u = at3(rx0,ry1,rz0);
    q = g3[ b11 + bz0 ] ; v = at3(rx1,ry1,rz0);
    b = lerp_m(t, u, v);

    c = lerp_m(sy, a, b);

    q = g3[ b00 + bz1 ] ; u = at3(rx0,ry0,rz1);
    q = g3[ b10 + bz1 ] ; v = at3(rx1,ry0,rz1);
    a = lerp_m(t, u, v);

    q = g3[ b01 + bz1 ] ; u = at3(rx0,ry1,rz1);
    q = g3[ b11 + bz1 ] ; v = at3(rx1,ry1,rz1);
    b = lerp_m(t, u, v);

    d = lerp_m(sy, a, b);

    return lerp_m(sz, c, d);
}
*/

static void normalize2(F32 v[2])
{
    F32 s;

    s = 1.f/(F32)sqrt(v[0] * v[0] + v[1] * v[1]);
    v[0] = v[0] * s;
    v[1] = v[1] * s;
}

static void normalize3(F32 v[3])
{
    F32 s;

    s = 1.f/(F32)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;
}

static void init(void)
{
    // we want repeatable noise (e.g. for stable terrain texturing), so seed with known value
    srand(42);
    int i, j, k;

    for (i = 0 ; i < B ; i++) {
        p[i] = i;

        g1[i] = (F32)((rand() % (B + B)) - B) / B;

        for (j = 0 ; j < 2 ; j++)
            g2[i][j] = (F32)((rand() % (B + B)) - B) / B;
        normalize2(g2[i]);

        for (j = 0 ; j < 3 ; j++)
            g3[i][j] = (F32)((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];
    }

    // reintroduce entropy
    srand(time(NULL));      // Flawfinder: ignore
}

#undef B
#undef BM
#undef N
#undef NF32
#undef NP
#undef NM

#endif // LL_NOISE_