// this function calculates the normal using the local coordinates;
SbVec3f Cone::calculate_normal(SbVec3f *starting_position, SbVec3f *ray_direction, float t){
SbVec3f poi, normal;
poi = point_of_intersection( starting_position, ray_direction, t);
normal[0] = -1 * poi[0];//(sp + (t *(rd))); //ntc
normal[1] = 1 * poi[1];
normal[2] = 1 * poi[2];
return normal;
}
/**
* @brief given a quad, this function applies linear regression to the points
* between each of the vertices to improve the estimate of where the
* vertices actually are
*
* @param quad the \c koki_quad_t* that should be refined
*/
void koki_quad_refine_vertices(koki_quad_t *quad)
{
koki_point2Df_t vects[4][2];
float vals[4][2];
koki_point2Df_t avgs[4];
GSList *start, *end;
if (quad == NULL)
return;
/* perform PCA on edges between vertices */
koki_debug(KOKI_DEBUG_INFO, "PCA on quad\n");
koki_debug(KOKI_DEBUG_INFO, "-----------\n");
/* side 0 (v0 --> v1) */
get_centre_section(quad->links[0], quad->links[1], &start, &end);
koki_pca(start, end, vects[0], vals[0], &avgs[0]);
pca_output_debug(vects[0], vals[0], avgs[0], 0);
/* side 1 (v1 --> v2) */
get_centre_section(quad->links[1], quad->links[2], &start, &end);
koki_pca(start, end, vects[1], vals[1], &avgs[1]);
pca_output_debug(vects[1], vals[1], avgs[1], 1);
/* side 2 (v2 --> v3) */
get_centre_section(quad->links[2], quad->links[3], &start, &end);
koki_pca(start, end, vects[2], vals[2], &avgs[2]);
pca_output_debug(vects[2], vals[2], avgs[2], 2);
/* side 3 (v3 --> [end]) */
get_centre_section(quad->links[3], NULL, &start, &end);
koki_pca(start, end, vects[3], vals[3], &avgs[3]);
pca_output_debug(vects[3], vals[3], avgs[3], 3);
/* set vertex positions based on the intersection of PCA's
significant eigen vectors */
/* vertex 0 (intersection of e3 and e0) */
quad->vertices[0]
= point_of_intersection(avgs[3],
significant_eigen_vector(vects[3], vals[3]),
avgs[0],
significant_eigen_vector(vects[0], vals[0]));
/* vertex 1 (intersection of e0 and e1) */
quad->vertices[1]
= point_of_intersection(avgs[0],
significant_eigen_vector(vects[0], vals[0]),
avgs[1],
significant_eigen_vector(vects[1], vals[1]));
/* vertex 2 (intersection of e1 and e2) */
quad->vertices[2]
= point_of_intersection(avgs[1],
significant_eigen_vector(vects[1], vals[1]),
avgs[2],
significant_eigen_vector(vects[2], vals[2]));
/* vertex 3 (intersection of e2 and e3) */
quad->vertices[3]
= point_of_intersection(avgs[2],
significant_eigen_vector(vects[2], vals[2]),
avgs[3],
significant_eigen_vector(vects[3], vals[3]));
}
