CGAL users discussion list

[Stephane Tayeb <>]

 wrote:
> Hi,
> I was wondering if it is possible to set an order evaluating intersections
> by means of the AABB Tree algorithm. In the documentation I find that "No
> particular order is guaranteed over the tree traversal, such that, e.g,
> the primitive returned is not necessarily the closest from the source
> point of a ray query". The algorithm follows the given order of the input
> primitives calculating intersections (for example a list of triangles
> composing tetrahedra)? Conversely I would like to follow a ray crossing a
> 3D object represented as a 3D complex ( for example a tetrahedron mesh in
> 3D mesh generation) and I need to control two consecutive ("couples" of
> closest intersected points) intersections and their relative distance.
> Thank in advance!

Hi,

I'm not sure to fully understand your concern but maybe this could help. 
There is a function which allows you to retrieve all the intersections 
between a ray and the primitives contained in the tree (named 
all_intersections).
Then you should be able to sort those intersection points along the ray 
to get what you want.

Concerning the order there is no way to specify it, it follows the 
internal tree structure.

Regards,
Stéphane.

--
Stephane Tayeb
Software engineer - INRIA Sophia Antipolis
Geometrica Project-Team