double gauss_height_fn(char *data,double x,double z)
{
gauss_info *gi = (gauss_info *) data;
dyv *xdyv = mk_dyv_2(x,z);
double result = gauss_eval(xdyv,gi->mu,gi->cov_inv,gi->cov_determinant);
free_dyv(xdyv);
return result;
}
/*
* Given a seg which participates in the partition we are shading evaluate
* the transmission on the path
*/
static double
eval_seg(struct application *ap, struct reg_db_internals *dbint, struct seg *seg_p)
{
double span;
point_t pt;
struct rt_ell_internal *ell_p = (struct rt_ell_internal *)dbint->ip.idb_ptr;
double optical_density = 0.0;
double step_dist;
double dist;
int steps;
/* XXX Should map the ray into the coordinate system of the ellipsoid
* here, so that all computations are done in an axis-aligned system
* with the axes being the gaussian dimensions
*/
span = seg_p->seg_out.hit_dist - seg_p->seg_in.hit_dist;
steps = (int)(span / 100.0 + 0.5);
if (steps < 2) steps = 2;
step_dist = span / (double)steps;
if (rdebug&RDEBUG_SHADE) {
bu_log("Evaluating Segment:\n");
bu_log("dist_in:%g dist_out:%g span:%g step_dist:%g steps:%d\n",
seg_p->seg_in.hit_dist,
seg_p->seg_out.hit_dist,
span, step_dist, steps);
}
for (dist=seg_p->seg_in.hit_dist; dist < seg_p->seg_out.hit_dist; dist += step_dist) {
VJOIN1(pt, ap->a_ray.r_pt, dist, ap->a_ray.r_dir);
optical_density += gauss_eval(pt, ell_p->v, dbint->one_sigma);
}
return optical_density;
}
