source: downloads/openal-0.0.8/src/al_vector.c @ 17

#include "al_siteconfig.h"

#include <AL/al.h>
#include <math.h>
#include <stdlib.h>

#include "al_debug.h"
#include "al_main.h"
#include "al_vector.h"

#ifndef M_PI
#define M_PI            3.14159265358979323846  /* pi */
#endif /* M_PI */


/*
 * _alVectorMagnitude( const ALfloat *origin, const ALfloat *v2 )
 *
 * Returns magnitude of v2 with origin at origin.
 *
 * FIXME: please check my math
 */
ALfloat _alVectorMagnitude( const ALfloat *origin, const ALfloat *v2 ) {
        ALfloat lsav[3];
        ALfloat retval;

        _alVectorDistance( lsav, origin, v2 );

        retval = sqrt( lsav[0] * lsav[0] +
                       lsav[1] * lsav[1] +
                       lsav[2] * lsav[2] );

        retval = fabs( retval );

        return retval;

}

/*
 * _alVectorNormalize( ALfloat *d, const ALfloat *s)
 *
 * Normalizes s, placing result in d.
 */
void _alVectorNormalize( ALfloat *d, const ALfloat *s) {
        ALfloat mag;

        mag = _alVectorMagnitudeAtZero( s );

        if( mag == 0 ) {
                d[0] = 0.0; d[1] = 0.0; d[2] = 0.0;

                return;
        }

        d[0] = s[0] / mag;
        d[1] = s[1] / mag;
        d[2] = s[2] / mag;

        return;
}

/*
 * _alVectorAngleBetween( const ALfloat *origin, const ALfloat *v1,
 *                       const ALfloat *v2 )
 *
 * Returns the angle between two vectors, with origins at origin.
 *
 * FIXME: please check my math
 */
ALfloat _alVectorAngleBetween( const ALfloat *origin, const ALfloat *v1,
                              const ALfloat *v2 ) {
        ALfloat m1;     /* |v2| */
        ALfloat m2;     /* |v1| */
        ALfloat mt;     /* |v1| * |v2| */
        ALfloat dp;    /*  dot product */
        ALfloat mag;

        m1  = _alVectorMagnitude( origin, v1 );
        m2  = _alVectorMagnitude( origin, v2 );
        dp  = _alVectorDotp( origin, v1, v2 );

        mt = m1 * m2;
        if(mt == 0.0f) {
                return M_PI / 2.0f;
        }

        mag = acos( dp / mt );

        return mag;
}

/*
 * _alVectorDotp( const ALfloat *origin, const ALfloat *v1,
 *              const ALfloat *v2 )
 *
 * Returns dot product between v1 and v2, with origin at origin.
 */
ALfloat _alVectorDotp( const ALfloat *origin, const ALfloat *v1,
                       const ALfloat *v2 ) {
        ALfloat o_inverse[3];
        ALfloat v1_trans[3];
        ALfloat v2_trans[3];
        ALfloat retval = 0.0f;

        _alVectorInverse( o_inverse, origin );

        _alVectorTranslate( v1_trans, v1, o_inverse );
        _alVectorTranslate( v2_trans, v2, o_inverse );

        retval += v1_trans[0] * v2_trans[0];
        retval += v1_trans[1] * v2_trans[1];
        retval += v1_trans[2] * v2_trans[2];

        return retval;
}