Resolved VR performance URP

I see a lot of people complaining about VR performance in the URP, especially on android (which is almost all standalone VR hardware).

Are there plans to fix this? It mostly comes from the lit shader according to CloudWalker.
This is limiting a lot of devs to 2020, so they will miss the 2021 and 2022 features

There is 1 issue fixed, 1 issue marked as duplicate falsly and 1 recent bug report which got through.

Info page:
https://forum.unity.com/threads/quest-2-performance-loss-2020-3-2021-3.1297833/#post-8446736

Bug reports:
https://issuetracker.unity3d.com/is...ot-2-and-trunk-shows-significant-gpu-increase

https://issuetracker.unity3d.com/is...-slower-than-2021-dot-3-when-built-on-quest-2

https://issuetracker.unity3d.com/issues/meta-quest-performance-loss-between-urp-versions-when-built

 

Thought it was just me! That performance regression when updating to 2021 is not fixed, no matter what those closed bug reports on the issue tracker suggest.

 

Anyone from the team?

 

This doesn't address the main issue (performance regression in newer versions), but I would say it's a little surprising that people are using URP/Lit instead of URP/SimpleLit or something custom on Quest 2. The XR2 on Quest 2 is not low-end mobile hardware by any means, but it has to render a lot more pixels than most phones.

It would be good to hear which shader Unity expects devs to use in mobile VR. Maybe they're not using URP/Lit in their own tests.

 

In the duplicate issue which wasn't duplicate I used lit shaders. Not sure about the other repro projects

 

but surely the whole point of the URP was that it was going to be mobile friendly?...
With specific reference to Quest2, I totally get needing to steer clear of screen space effects because of the tiled rendering but lit shaders... really? Personally I'm finding @jbooth 's BetterLitShaders to work great. My point is that porting a project with no changes from 2020 to 2021 should not lose me 3ms. With a frame budget of only 13.7ms for 72Hz (I usually like to aim for more) that's too much of a hit to swallow. I just went straight back to 2020.

 

Interesting to use custom lighting. Might look into it for some objects in our game!

 

The VRChat crowd have been big on matcap materials for a good reason

 

Maybe this is a miscommunication issue as well. I would view using URP/Lit for mobile VR the same as using Standard in built-in; not recommended unless you have a particularly simple scene.

URP/Lit is certainly more performant than Standard, especially when it comes to real-time lights, but it's still a PBR shader and you're always going to pay a performance tax to do physically based rendering.

So, URP/SimpleLit should be used on Quest, or if you want to squeeze as much performance and quality as you can, a custom shader tailor-made for your game is always going to be better than a general purpose one.

 

Totally agree, SimpleLit is the way, but what was being suggested was Unlit. Not everyone has the knowhow to write their own (performant) shaders so we rely on the engine team, or third party sellers.

 

One of the biggest performance issues for mobile VR is texture bandwidth, and the standard lit shader is terrible here. You can pack a full PBR material down to as little as 2 textures, but the URP lit shader uses 5. I'm sure that was done to make it use the same layout as BiRP, so that switching would be easier, but it does hurt performance. (Also there are quality downsides to doing this from compression, but even so a better layout like the one HDRP uses would have been nice)

 

Any updates from the XR team?

 

Sounds good!
If people comment on performance issues I always recommend them to submit the project in a bug report to have a repro project

 

The Oculus Integration update (47) seems to have fixed this for me. It came out yesterday.

 

Nice! Unity 2021.3.14 and newer also have good performance improvements