grid do not work with raytracing

[mwestphal]

Describe the bug
grid do not work with raytracing

To Reproduce
Steps to reproduce the behavior:

1. Open the file using f3d --dry-run -rng
2. Rendering is incorrect

Expected behavior
Like this but raytracing:

System Information:

• OS: Archlinux

F3D Information
1.3.1

Additional context
Interactively disabling and enabling raytracing makes the filenames appears. Grid never appears.

[mwestphal]

@Meakk any idea if we can ever fix that for the grid ?

Text actor will be fixed once we have #1077

[Meakk]

I think I already fixed the text actor by running OSPRay pass for 3D objects only and have another OpenGL pass for the overlay.
Regarding the grid, it might be possible if we can retrieve the depth buffer from OSPRay and composite the grid on top of it.

[mwestphal]

I think I already fixed the text actor by running OSPRay pass for 3D objects

Indeed!