Bug: Brush-lightmapped entities are not affected by csm.

[Unusuario2]

Describe the bug

When making a Brush-lightmapped entity like func_tracktrain, func_brush, etc... and you parent the entity, csm does not overwrite the lightmap lighting as it does in prop_dymanics. See the video:

https://github.com/user-attachments/assets/d066238e-18d1-4ef3-b779-2a8d7f81473e

To Reproduce

1. Download the map example.
2. Compile & run the map.
3. See the behaviour.

Issue Map

enginetest.zip

Expected Behavior

Brush-lightmapped entities are not affected by csm

Operating System

Windows 10

[MyGamepedia]

This is so, because csm is baked on world geometry and bmodels, using lightmap alpha mask. You can use Propper or Propper++ to workaround it by converting your bmodel.