/ray/src/lib/numerics/noise/perlin.cc

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/*
 * lib/numerics/perlin.cc
 * 
 * Perlins famous noise function. 
 * 
 * Copyright (c) 2004 by Klaus Sausen (nicolasius § users.sourceforge.net)
 *                   and Wolfgang Wieser ] wwieser (a) gmx <*> de [. 
 * 
 * This implementation of the "Perlin noise" is a modification of Ken 
 * Perlin's original implementation as available on his homepage. 
 * 
 * This file may be distributed and/or modified under the terms of the 
 * GNU General Public License version 2 as published by the Free Software 
 * Foundation. (See COPYING.GPL for details.)
 * 
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 * 
 */

#include "perlin.h"


namespace NUM  // numerics
{

template<typename T>void NoiseGenerator_Perlin<T>::_init()
{
    int i,j;

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

        //g1[i] = (T)((rand() % (B + B)) - B) / B;
        g1[i] = (T)((rand() & (2*B-1)) - B) / B;

        for(j=0 ; j<2 ; j++)
            g2[i][j] = (T)((rand() & (2*B-1)) - B) / B;
            //g2[i][j] = (T)((rand() % (B + B)) - B)) / B;

        // Normalize g2[i]:
        T s = T(1.0)/hypot(g2[i][0],g2[i][1]);
        g2[i][0] *= s;
        g2[i][1] *= s;

        for(j=0 ; j<3 ; j++)
            g3[i][j] = (T)((rand() & (2*B-1)) - B) / B;
            //g3[i][j] = (T)(((rand() % (B + B)) - B) / B);

        // Normalize g3[i]: 
        s = T(1.0)/sqrt(sqr(g3[i][0]) + sqr(g3[i][1]) + sqr(g3[i][2]));
        g3[i][0] *= s;
        g3[i][1] *= s;
        g3[i][2] *= s;
    }

    // Permutate p[]...
    while(--i)
    {
        int k = p[i];
        //p[i] = p[j = rand() % B];
        p[i] = p[j = rand() & (B-1)];
        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];
    }
}


#define s_curve(t)   ( t * t * (T(3.0) - T(2.0) * t) )

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

#define setup(i,b0,b1,r0,r1)\
    t = vc[i] + N;\
    b0 = ((int)t) & (B-1);\
    b1 = (b0+1) & (B-1);\
    r0 = t - (int)t;\
    r1 = r0 - 1.;


template<typename T>T NoiseGenerator_Perlin<T>::noise1(T arg) const
{
    int bx0, bx1;
    T rx0, rx1, sx, t, u, v, vc[1];
    
    vc[0] = arg;
    
    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);
}


template<typename T>T NoiseGenerator_Perlin<T>::noise2(const T *vc) const
{
    int bx0, bx1, by0, by1, b00, b10, b01, b11;
    T rx0, rx1, ry0, ry1, sx, sy, a, b, t, u, v;
    const T *q;
    register int i, j;
    
//#define setup(i,b0,b1,r0,r1)
//  setup(0, bx0,bx1, rx0,rx1);
//  setup(1, by0,by1, ry0,ry1);

    t = vc[0] + N;
    bx0 = ((int)t) & (B-1);
    bx1 = (bx0+1) & (B-1);
    rx0 = t - (int)t;
    rx1 = rx0 - T(1.0);

    t = vc[1] + N;
    by0 = ((int)t) & (B-1);
    by1 = (by0+1) & (B-1);
    ry0 = t - (int)t;
    ry1 = ry0 - T(1.0);

    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);

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

    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 T(lerp(sy, a, b));
}


template<typename T>T NoiseGenerator_Perlin<T>::noise3(const T *vc) const
{
    int bx0, bx1, by0, by1, bz0, bz1, b00, b10, b01, b11;
    T rx0, rx1, ry0, ry1, rz0, rz1, sy, sz, a, b, c, d, t, u, v;
    const T *q;
    register int i, j;

//  setup(0, bx0,bx1, rx0,rx1);
//  setup(1, by0,by1, ry0,ry1);
//  setup(2, bz0,bz1, rz0,rz1);
    t = vc[0] + N;
    bx0 = ((int)t) & (B-1);
    bx1 = (bx0+1) & (B-1);
    rx0 = t - (int)t;
    rx1 = rx0 - T(1.0);

    t = vc[1] + N;
    by0 = ((int)t) & (B-1);
    by1 = (by0+1) & (B-1);
    ry0 = t - (int)t;
    ry1 = ry0 - T(1.0);

    t = vc[2] + N;
    bz0 = ((int)t) & (B-1);
    bz1 = (bz0+1) & (B-1);
    rz0 = t - (int)t;
    rz1 = rz0 - T(1.0);

    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(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 T(lerp(sz, c, d));
}


void _NoiseGenerator_PerlinInstantiationDummy()
{
    {
        NoiseGenerator_Perlin<dbl> p;
        p.noise1(0);
        p.noise2(NULL);
        p.noise3(NULL);
    }
    {
        NoiseGenerator_Perlin<flt> p;
        p.noise1(0);
        p.noise2(NULL);
        p.noise3(NULL);
    }
}

}  // end of namespace NUM

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