How to Sample Depth Texture in UE 4.27

Development Programming & Scripting C++
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1

As part of our plugin, we’ve written code to access the DeviceDepth in a callback to IRendererModule::RegisterPostOpaqueRenderDelegate using a DrawPrimitive call, and convert it to a suitable SceneDepth ourselves. In versions 4.22 - 4.26 of UE, this works great (picture a nice normal depth map), but in version 4.27, I instead get a very weird pattern:

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image899×504 2.13 KB

This is from reading out FPostOpaqueRenderParameters::DepthTexture , passed to the callback by the event itself, so I would’ve expected everything to stay the same.
I’ve attached the core code that we’re calling in case it helps.
OpaqueGrab.cpp (9.5 KB)

2

I’ve narrowed this down slightly in that it seems to only happen with DX12 as the RHI (UE 4.26+DX12 works fine). I’ve tried calling RHICmdList->TransitionResource on the DepthTexture in case that was required but it just resulted in a pure white texture which seems like a lateral move at best.

Edit: In contrast to the code I shared above, I’ve also tried using RHICopySubTextureRegion_RenderThread in PostResolve to no effect - I get a pure white tex there as well.