Bug Missing bounce lighting on GPU instanced object with custom shader

Take a look at the following image:


All objects are statically lit. However, the ones that use a custom (shadergraph as I'm using URP) shader and use a second UV channel for their lightmaps don't produce bounce lighting at all. It doesn't matter if that second UV channel is authored externally (as for the meshes on the right) or generated with the "Auto generate lightmaps" option.

This happens with both the CPU and GPU lightmapper.

I've already submitted a bug report with this scene, but since it can take a while for those to get fixed, I'm hoping someone else might have encountered this too and found a workaround. It is especially worrisome in WebGL (which I'm working in) as the SRP batcher is not supported there and GPU instancing is one of the few tools you can use to reduce drawcalls.

 

This looks extremely similar to the problem I reported here: https://forum.unity.com/threads/inc...with-shadergraph-and-auto-lightmap-uv.901214/

 

They indeed look similar. Both can be explained by an erroneous black albedo from the GI perspective. Shame that it has been known for a while and not addressed though :/

 

Thanks, just received confirmation that it was added to the issuetracker:

https://issuetracker.unity3d.com/product/unity/issues/guid/1253185

Hope it gets resolved soon!

 

The bug does not exist in 2019.4 LTS?

"
Found in

2019.3
2019.3.13f1
"

 

It does, the testers probably only tried that version as it is the one I used for my reproduction scene, but it happens in 2019.4 too.

 

So basically baked lighting is wrong if a scenes has material with a Shadergraph material?

 

Yes, although you can work around it by using a single UV channel for both the main texture and the lightmap, though that is obviously quite limiting and undesirable in a lot of cases.

 

That's really a horrible bug. No words from Unity?