How to support multiple render pipelines?

[mlavik1]

I'd like to add proper support for Unity's Unified Render Pipeline, and maybe also the High Definition Render Pipeline.
However, there are some challenges I'm not sure about how to solve:

• A lot of people seem to use this project by adding it as a subdirectory to their project, or by including it as a git submodule. I don't want to require these users to have URP (and maybe HDRP too) included in their project, if they are not going to use it.
• I want to avoid having to generate one unitypackage for each RP. This will easily scale badly (if I want to package with/without SimpleITK included as well, we need to provide 2x3=6 packages!).

I've looked around to see what others do, and I've seen two approaches:

• Expect users to have URP available. If they don't, they will get some errors when they open it, and have some assets with "missing script" (RP assets).
• Same as above for main repository, but provide separate unitypackages for each RP (also legacy). Not sure what to do with the Unity Asset Store version though?

Neither of these sound like a good solution to me though.. What I would prefer is to be able to write shaders (and maybe create materials) for each RP (legacy, URP, maybe HDRP), and in code determine which to use depending on the active RP. However, there doesn't seem to be a way to make Unity "ignore" assets based on the availability of another package (URP, HDRP).

Maybe I'm missing something, but if anyone has some suggestions please let me know! :)

[mlavik1]

Update: Got a reply: https://forum.unity.com/threads/urp-hdrp-as-optional-dependencies.1364844/

My suggestion:

• Remove all materials, and create them from code instead.
• Create shaders for all RP
• Add UNITY_HDRP / UNITY_URP defines (as suggested in forum answer linked above) to HDRP/URP-related code.