/**
* Algorithm -
*
* From the four corners of the surface, return the two parts split by
* the diagonal from the first and third corner point making sure
* Homogeneous points are divided.
*/
struct rt_nurb_poly *
rt_nurb_to_poly(struct face_g_snurb *srf)
{
int coords = srf->pt_type;
fastf_t * p1, *p2, *p3, *p4;
fastf_t uv1[2], uv2[2], uv3[2], uv4[2];
struct rt_nurb_poly *p, *p_head;
/* Extract the four corners from the mesh */
p1 = srf->ctl_points;
p2 = srf->ctl_points + coords * srf->s_size[1];
p3 = srf->ctl_points + (coords * srf->s_size[1] *
(srf->s_size[0] - 1)) +
((srf->s_size[1] - 1) * coords);
p4 = srf->ctl_points + (coords * srf->s_size[1] *
(srf->s_size[0] - 1));
/* If the point is rational then divide out the w component */
if (RT_NURB_IS_PT_RATIONAL(srf->pt_type)) {
int w_index;
if (RT_NURB_EXTRACT_PT_TYPE(srf->pt_type) == RT_NURB_PT_XY)
w_index = 2;
else if (RT_NURB_EXTRACT_PT_TYPE(srf->pt_type) == RT_NURB_PT_UV)
w_index = 2;
else if (RT_NURB_EXTRACT_PT_TYPE(srf->pt_type) == RT_NURB_PT_XYZ)
w_index = 3;
else /* assume the forth coordinate */
w_index = 3;
p1[0] = p1[0] / p1[w_index];
p2[0] = p2[0] / p1[w_index];
p3[0] = p3[0] / p1[w_index];
p4[0] = p4[0] / p1[w_index];
}
uv1[0] = srf->u.knots[0];
uv1[1] = srf->v.knots[0];
uv2[0] = srf->u.knots[srf->u.k_size -1];
uv2[1] = srf->v.knots[0];
uv3[0] = srf->u.knots[srf->u.k_size -1];
uv3[1] = srf->v.knots[srf->v.k_size -1];
uv4[0] = srf->u.knots[0];
uv4[1] = srf->v.knots[srf->v.k_size -1];
p = rt_nurb_mk_poly(p1, p2, p3, uv1, uv2, uv3);
p_head = p;
p = rt_nurb_mk_poly(p3, p4, p1, uv3, uv4, uv1);
p->next = p_head;
p_head = p;
return p_head;
}
void
rt_nurb_print_pt_type(int c)
{
int rat;
rat = RT_NURB_IS_PT_RATIONAL(c);
if (RT_NURB_EXTRACT_PT_TYPE(c) == RT_NURB_PT_XY)
bu_log("Point Type = RT_NURB_PT_XY");
else
if (RT_NURB_EXTRACT_PT_TYPE(c) == RT_NURB_PT_XYZ)
bu_log("Point Type = RT_NURB_PT_XYX");
else
if (RT_NURB_EXTRACT_PT_TYPE(c) == RT_NURB_PT_UV)
bu_log("Point Type = RT_NURB_PT_UV");
if (rat)
bu_log("W\n");
else
bu_log("\n");
}
