math_geom_inline.c

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/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: some of this file.
 *
 * ***** END GPL LICENSE BLOCK *****
 * */

#include "BLI_math.h"

#ifndef BLI_MATH_GEOM_INLINE_H
#define BLI_MATH_GEOM_INLINE_H

/****************************** Spherical Harmonics **************************/

MINLINE void zero_sh(float r[9])
{
    memset(r, 0, sizeof(float)*9);
}

MINLINE void copy_sh_sh(float r[9], const float a[9])
{
    memcpy(r, a, sizeof(float)*9);
}

MINLINE void mul_sh_fl(float r[9], const float f)
{
    int i;

    for(i=0; i<9; i++)
        r[i] *= f;
}

MINLINE void add_sh_shsh(float r[9], const float a[9], const float b[9])
{
    int i;

    for(i=0; i<9; i++)
        r[i]= a[i] + b[i];
}

MINLINE float dot_shsh(float a[9], float b[9])
{
    float r= 0.0f;
    int i;

    for(i=0; i<9; i++)
        r += a[i]*b[i];
    
    return r;
}

MINLINE float diffuse_shv3(float sh[9], const float v[3])
{
    /* See formula (13) in:
       "An Efficient Representation for Irradiance Environment Maps" */
    static const float c1 = 0.429043f, c2 = 0.511664f, c3 = 0.743125f;
    static const float c4 = 0.886227f, c5 = 0.247708f;
    float x, y, z, sum;

    x= v[0];
    y= v[1];
    z= v[2];

    sum= c1*sh[8]*(x*x - y*y);
    sum += c3*sh[6]*z*z;
    sum += c4*sh[0];
    sum += -c5*sh[6];
    sum += 2.0f*c1*(sh[4]*x*y + sh[7]*x*z + sh[5]*y*z);
    sum += 2.0f*c2*(sh[3]*x + sh[1]*y + sh[2]*z);

    return sum;
}

MINLINE void vec_fac_to_sh(float r[9], const float v[3], const float f)
{
    /* See formula (3) in:
       "An Efficient Representation for Irradiance Environment Maps" */
    float sh[9], x, y, z;

    x= v[0];
    y= v[1];
    z= v[2];

    sh[0]= 0.282095f;

    sh[1]= 0.488603f*y;
    sh[2]= 0.488603f*z;
    sh[3]= 0.488603f*x;
    
    sh[4]= 1.092548f*x*y;
    sh[5]= 1.092548f*y*z;
    sh[6]= 0.315392f*(3.0f*z*z - 1.0f);
    sh[7]= 1.092548f*x*z;
    sh[8]= 0.546274f*(x*x - y*y);

    mul_sh_fl(sh, f);
    copy_sh_sh(r, sh);
}

MINLINE float eval_shv3(float sh[9], const float v[3])
{
    float tmp[9];

    vec_fac_to_sh(tmp, v, 1.0f);
    return dot_shsh(tmp, sh);
}

MINLINE void madd_sh_shfl(float r[9], const float sh[3], const float f)
{
    float tmp[9];

    copy_sh_sh(tmp, sh);
    mul_sh_fl(tmp, f);
    add_sh_shsh(r, r, tmp);
}

#endif /* BLI_MATH_GEOM_INLINE_H */