Add possibility to handle multiple intersections

[Sheol27]

Hi! Right now there is the function intersect_1, but as the name says it returns only the first intersection. It would be awesome if we could have all the intersections of the ray, like it happens in the python library. Is it possible to add this feature ?

[psytrx]

Hi!

If I remember correctly, embree only supports intersections for packets of size 2^n, up to 16 at most. For these sizes it should be straightforward to implement.

For finding all intersections, we'd have to repeatedly call intersect_16 (while increasing tnear) until the result set is empty.
I can see this being a feature, but am currently unable to look into the details.
Some thoughts: We should be able to do this in parallel. This may turn out as a challenge though, since we're handling raw pointers under the hood. Also, an upper bound may be known by the developer - this could improve performance if we're choosing a sensible approach (don't allocate unnecessarily large packets, etc).

Can you provider a link to the Python library your are referring to?

As noted, I'm currently unable to look into it in the short term, but open to suggestions or PRs!