CGAL users discussion list

["Wesley Smith" <>]

I peresonally found this operation in CGAL a bit lacking, so I use the
code from Tomas Moller:
http://www.cs.lth.se/home/Tomas_Akenine_Moller/raytri/raytri.c

You can google their paper describing the method.  It gives values (t,
u, v) where t is the distance along the ray to the intersection point
and u and v are barycentric coordinates of the intersection on the
triangle.

Sample usage:

void ray_mesh_intersction(vector<Facet> &facets, const Ray &r)
{
        Point o = r.source();
        Direction d = r.direction();
        
        double orig[] = {o.x(), o.y(), o.z()};
        double dir[] = {d.dx(), d.dy(), d.dz()};
        
        for(int f = 0; f < facets.size(); f++) {
                Triangle tri = V->dual().triangle(facets[f]);
                
                double vert0[] = {tri.vertex(0).x(), tri.vertex(0).y(), 
tri.vertex(0).z()};
                double vert1[] = {tri.vertex(1).x(), tri.vertex(1).y(), 
tri.vertex(1).z()};
                double vert2[] = {tri.vertex(2).x(), tri.vertex(2).y(), 
tri.vertex(2).z()};
                double t, u, v;

                if(intersect_triangle2(orig, dir, vert0, vert1, vert2, &t, 
&u, &v)) {
                        if(t > 0) {
                                //printf("intersect: %f %f %f\n", t, u, v);
                                //intersect point is Point(t*dir[0]+orig[0], 
t*dir[1]+orig[1],
t*dir[2]+orig[2]);
                        }
                }
        }
}