Make volumetric fog GI Inject take LightmapGI into account

[atirut-w]

Describe the project you are working on

N/A

Describe the problem or limitation you are having in your project

As of currently, only real-time GI and ambient lighting effects volumetric fog. It would be nice if baked GI can also effect VF, since some games might not want completely real-time lighting. A good example of this are competitive shooting games.

Describe the feature / enhancement and how it helps to overcome the problem or limitation

This helps VF look more realistic in games with baked GI that does not make use of real-time GI techniques.

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

No idea.

If this enhancement will not be used often, can it be worked around with a few lines of script?

Probably not.

Is there a reason why this should be core and not an add-on in the asset library?

See above.

[Calinou]

Lightmaps can optionally store probes for dynamic object lighting, but I don't think sampling this data in volumetric fog would be efficient.

If you really want to use LightmapGI with volumetric fog using GI Inject, use VoxelGI and LightmapGI at the same time. VoxelGI will not affect surfaces that receive baked lighting, so this will be faster to render compared to only using VoxelGI. This also allows dynamic objects to receive high-quality reflections.

[clayjohn]

I have a feeling sampling the probes may be similar performance wise to sampling VoxelGI. It would be nice to reduce the memory footprint if users are already using baked lightmaps.

This is certainly worth exploring as I don't think it will be very hard to get a proof of concept going.