Modifying the VisibleLight List and Remapping Light Indices

Hey all,

I have a question concerning the general usage of these APIs:

https://docs.unity3d.com/ScriptReference/Rendering.CullingResults.GetLightIndexMap.html
and
https://docs.unity3d.com/ScriptReference/Rendering.CullingResults.SetLightIndexMap.html

If I wanted to sort the VisibleLight array by something like distance-to-Camera, what is the correct behaviour for dealing with the index map?

Currently I have this scenario (in psuedo code)

Code (CSharp):

1. // swap 2 Light's position in the array
2. VisibleLight tempLight = visibleLights[l];
3. visibleLights[l] = visibleLights[r];
4. visibleLights[r] = tempLight;
5.  
6. // swap the indices in the index map
7. int tempIndex = lightIndexMap[l];
8. lightIndexMap[l] = lightIndexMap[r];
9. lightIndexMap[r] = tempIndex;
10.  
11. cullingResults.SetLightIndexMap(lightIndexMap);
12.  

At this point, whether I do the custom sort or not (and assuming I'm understanding the API correctly), I'd assume that the Per-Object light culling result would be the same since it does its sorting/culling based on Unity's internal heuristics. However the result I receive is different based on whether or not I do my custom sort. The sort itself works as intended, so my suspicion is that I am misusing the aforementioned API.

Any help would be greatly appreciated!

Cheers,
==

 

I think the SRP not support change culling results directly now.

 

But we really need do some custom culling or resort things after engine's culling.
That really sucks , we can not inject culling things.

 

The API is in use here, so it does actually do *something* https://github.com/Unity-Technologi...lines.universal/Runtime/ForwardLights.cs#L326

 

I think we need more custom ability with Culling things.

 

Thanks Felipe! I've got it working correctly now.

I now see how I was misinterpreting the API. I was assuming that I needed to

GetLightIndexMap

, reorder it based on my sort and then pass it back immediately after the sort. That doesn't seem to be the case, as reflected in your sample. I was thinking the index map corresponded to where the Light exists in Unity's internal "all the lights in the scene" array, not the original indices of the

VisibleLight

array handed to us by the

CullingResults

. All the same, it does seem like this could be made easier if VisibleLight just had a member that was the index it originally had, no? I may be missing something though.

In regards to an API for doing the sort outside of Managed Code, I certainly wouldn't be opposed to it, but I'm personally fine without it. I could see it being useful in a broader scope to be able to provide

ScriptableCullingParameters

an enum or flags for heuristics on how Lights get sorted on cull. That would probably be able to hit a majority of cases. But personally I want the absolute control to sort however I like.

Thanks again!