Raytracing and pointsprites do not work well together

[mwestphal]

Describe the bug
Raytracing and pointsprites do not work well together and eventually hangs F3D

To Reproduce
Steps to reproduce the behavior:

1. Open the file using f3d --dry-run cow.vtp -ro
2. Rendering is incorrect, should show point sprites in raytracing, only show raytracing

Expected behavior
Correct rendering at all steps

[mwestphal]

@Meakk do you know if this could ever work ? It (kinda) work in ParaView at least.

[Meakk]

We could I guess by just using the regular polydata mapper instead of point gaussian with the "render point only" option?

[mwestphal]

Not great imo. Lets wontfix this for now.

[mwestphal]

Still present in 3.0