Tile lighting problems appears when using unreasonable lights and subsurface scattering

[Revmatek]

Is there an existing issue for this?

• I have searched the existing issues.

Have you checked the documentation to resolve your problem?

• I have read the linked documentation and could not resolve my issue.

Current Behavior

If I manually add a bunch of lights to the main scene, it seems to affect the ocean tiles negatively as one or more tiles will become over saturated/brightly lit. I allow players to add lights to boats in various unreasonable configurations. Making large lights seems to be the key factor here (500 meter range).

Expected Behavior

Adding lights should not affect the ocean tiles revealing an obvious tile pattern.

Steps To Reproduce

1. Open main scene
2. Create a light source near the surface with a range of 500
3. Duplicate it 20 times
4. Disable foam on the ocean material (makes it easier to see)
5. Observe some sort of lighting artifacts are appearing on tiles
6. Disable subsurface scattering on the ocean material
7. Observe lighting artifacts now disappear

Workaround

I think I may be able to fix / ignore this by simply not having the lights affect the water layer.

Unity Version

2021.3.26f1

Crest Version

4.21.4

Render Pipeline

Built-In

Editor or Standalone

Standalone, Editor (Edit Mode), Editor (Play Mode)

Environment

- OS:Windows 11

Anything else?

I was under the impression the point lights were not supported at all so I was surprised it had an effect on the tiles, but I assume this is coming from some pass associated with subsurface scatting and lighting.

It definitely seems related to subsurface scatting because turning it off makes the tile lighting disappear. Having several large lights in one location can also make tiles below more reasonable light sources appear bright / different even if they are far away, but more so the closer they are to the large sources.

There are lots of lights that I should/could be restricting in some way, but it still seems like a bug.

[magenta404]

I had a look and the tiling is caused by spherical harmonics which we use for ambient lighting. This is likely a bug or limitation with Unity.

As a workaround. Enable Shader API on the UnderwaterRenderer, and return _CrestAmbientLighting in the following instead of SH:

crest/crest/Assets/Crest/Crest/Shaders/OceanLightingHelpers.hlsl

Line 27 in 364fc03

return half3(unity_SHAr.w, unity_SHAg.w, unity_SHAb.w);

This should lock ambient lighting to one source. And it appears not to pick up the additional lights.