Many triangles!

[kaanaksit]

The example, test/test_learn_ray_intersect_w_a_triangle.py, deals with a ray and a batch of rays. However, objects represented with triangles are typically described with many triangles but not one. Given the information, we challenge readers to create a new function inside odak.learn.raytracing submodule named intersect_w_mesh. This new function has to be able to work with multiple triangles (meshes) and has to be aware of "occlusions" (e.g., a triangle blocking another triangle). In addition, a new unit test, test/test_learn_ray_intersect_w_mesh.py, has to adopt this new function. To add these to odak, you can rely on the pull request feature on GitHub. You can also create a new engineering note for arbitrary surfaces in docs/notes/raytracing_meshes.md.