noise.h

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#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)
{
        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];
        }
}

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

#endif // LL_NOISE_

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