Function intersect_triangle

src/Util/Raytracer.cpp:92–156

}

int intersect_triangle(double orig[3], double dir[3], double vert0[3], double vert1[3], double vert2[3], double *t,
                       double *u, double *v) {
    double edge1[3], edge2[3], tvec[3], pvec[3], qvec[3];
    double det, inv_det;


#define CROSS(dest, v1, v2) \
          dest[0]=v1[1]*v2[2]-v1[2]*v2[1]; \
          dest[1]=v1[2]*v2[0]-v1[0]*v2[2]; \
          dest[2]=v1[0]*v2[1]-v1[1]*v2[0];
#define DOT(v1, v2) (v1[0]*v2[0]+v1[1]*v2[1]+v1[2]*v2[2])

#define SUB(dest, v1, v2) \
          dest[0]=v1[0]-v2[0]; \
          dest[1]=v1[1]-v2[1]; \
          dest[2]=v1[2]-v2[2];


    /* find vectors for two edges sharing vert0 */
    SUB(edge1, vert1, vert0);
    SUB(edge2, vert2, vert0);

    /* begin calculating determinant - also used to calculate U parameter */
    CROSS(pvec, dir, edge2);

    /* if determinant is near zero, ray lies in plane of triangle */
    det = DOT(edge1, pvec);

    /* calculate distance from vert0 to ray origin */
    SUB(tvec, orig, vert0);
    inv_det = 1.0 / det;

    CROSS(qvec, tvec, edge1);

    if (det > EPSILON) {
        *u = DOT(tvec, pvec);
        if (*u < 0.0 || *u > det)
            return 0;

        /* calculate V parameter and test bounds */
        *v = DOT(dir, qvec);
        if (*v < 0.0 || *u + *v > det)
            return 0;

    }
        /*else if(det < -EPSILON)
        {
           // calculate U parameter and test bounds
           *u = DOT(tvec, pvec);
           if (*u > 0.0 || *u < det)
          return 0;

           // calculate V parameter and test bounds
           *v = DOT(dir, qvec) ;
           if (*v > 0.0 || *u + *v < det)
          return 0;
        }*/
    else return 0;  /* ray is parallell to the plane of the triangle */