Question URP RendererFeatures and stereo cameras

Hi all,

I'm trying to adapt our fog and outline image effects to work in VR, but so far it's been just shooting in the dark.

The image effects are implemented as RendererFeature with a `ScrptableRenderPass`. Both fog and the outline effects use the opaque and depth maps in the HLSL shaders. Both effects work in the multi-pass VR mode, but give incorrect results in the single-pass mode.

I've looked at other URP's RendererFeatures - the SSAO and post-processing, but couldn't reverse engineer what's going on there with the XR stereo cameras support.

Is there any documentation how to handle the stereo rendering with RendererFeature? Any help is greatly appreciated.

 

Thank you Thomas,

Is there a reason the temporary buffers are rendered as a fullscreen quad as opposed to using

commandBuffer.Blit()

?

 

Another question, is world position reconstruction needed for image-space depth/normal-based edge detection in single-pass stereo? Can I sample the depth texture using

SampleSceneDepth()

or do I need this code as well?

 

Thanks for the references but I really feel like Unity should provide some bare bones examples for these instead of making the users decipher larger built-in URP effects. Would be a lot nicer to get example on how to make some naive effect using RendererFeatures that works in URP VR with SPI, for example simple desaturation example would be fine.

A good example is how HDRP custom PP does this on their docs, they provide a simple snippet that works and gives entry point for users digging into these things:
https://docs.unity3d.com/Packages/c...finition@12.0/manual/Custom-Post-Process.html

Making everyone go through the hard way is bit silly IMHO especially considering how huge painpoint URP VR is for everyone doing custom effects atm. Just look at the Asset Store where practically no 3rd party asset currently works in URP VR using recent URP versions. Simple examples go a long way in cases like these.

 

I agree. Alternatively to adding a new sample, Unity can at least update this one (which doesn't work with single-pass XR): https://github.com/Unity-Technologies/UniversalRenderingExamples.

 

+1. We're really unable to do any URP SPI work with VR when it comes to image effects. Really need an example for us to understand this better.

 

I put together a simple saturation effect made with URP Renderer Feature:
https://github.com/0lento/URP_RendererFeature_SPI_Example

Tested with both SPI + Multipass on MockHDM, OculusXR and OpenXR.

Do ignore the console error spam while using MockHMD, it's not related to this project but to MockHMD issue with new Input System (https://forum.unity.com/threads/att...eature-type-id-1-while-using-mockhmd.1021825/)

Edit: Updated the repo to have separate commits for old cmd.Blit and cmd.DrawMesh approaches so you can see what needs to change from the commit diff. Added also extra branch where I put similar RT handling as what Unity does on SSAO, wanted to keep this separate as it makes the overall change look bit more complicated than what it is.

 

I see Unity is now adding simpler Depth debug example to official URP docs (PR still draft / not final)

https://github.com/Unity-Technologies/Graphics/pull/5395

Thanks @ThomasZeng

 

This is great @rz_0lento. But I can't get it to work, the same as Unity's guide: https://docs.unity.cn/Packages/com....eatures/how-to-fullscreen-blit-in-xr-spi.html

In the frame debugger the pass seems to work, but then the "FinalBlit" seems to undo everything I already did.

Any suggestions?

I'm using:

Unity 2021.2.5f1
URP: 12.1.2
OpenXR: 1.3.1
Oculus: 3.0.0-pre.1

 

@Tomas the approach described in "How to perform a full screen blit in Single Pass Instanced rendering in XR" doesn't work in the latest URP. The effect is not applied and an error is shown in the console: `You can only call cameraColorTarget inside the scope of a ScriptableRenderPass. Otherwise the pipeline camera target texture might have not been created or might have already been disposed.`

Can you please update the instructions?

 

Second that, a working example would help a lot