5.4 preview -> 5.4.0 Forward Rendering Dynamic Lighting Regression (VR Template)

Development Rendering
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Just updated from preview to UE5.4.0 release to open the VR template and realize dynamic shadow casting is now broken.

CSM_Busted
CSM_Busted1919×1046 166 KB

I’ve added a UDN post and reproduction steps to get some eyes on it.

Wanted to share with the community and also let you know that you can disable instanced stereo

vr.InstancedStereo=False

CSM_Workaround
CSM_Workaround1593×771 96.8 KB

in your engine.ini as a work around (Please note that this drastically impacts performance!!!)

Hopefully this saves anyone currently working in preview from updating only to majorly impact their workflow.

Here’s to hoping a hotfix comes soon :slight_smile:

Happy Developing!

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This! It’s nice to see that I’m not the only one facing this problem. I spent the whole evening fiddling around and couldn’t figure out what was going on after updating to 5.4.0. I hope this will be fixed soon, although it feels like the developers have given up on VR.

Btw could you share your GPU model? I have a 5700xt and was wondering if it might be an issue with the AMD GPU in general.

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It’s confirmed as a bug and can currently be fixed by modifying the shader code here

https://github.com/EpicGames/UnrealEngine/commit/90ef97eee45bdb2665fafbd49d3784241ddba202

It requires recompiling shaders. UDN has mentioned a target fix for 5.5 and probably not a 5.4 hotfix due to it impacting shader cache ddc unfortunately

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hey @Uno1982 can confirm. Your fix works! Thanks buddy.

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Your link looks down? Getting a 404

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@B.Aware No it’s not down. You need to be in the Epic Games org in GitHub. Here is how to get access to the source code of UE: https://www.unrealengine.com/en-US/ue-on-github

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Give this a shot for those of you that want to keep instanced stereo enabled.

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Very welcome… also updated the post with a fix that doesn’t require disabling instanced stereo.

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I have another question since Unreal enigne 5 there is not a single 5.x version that support Dnyamic spotligh shadows for standalone? Any fixes for that. For Unreal enigne 4 everthing works as expected (dynamci spotlgith shadowsn standalone)

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They have fixes noted for UE5.4.2 but I’m not sure it actually works. I’ll update once I have a chance to test. Been a minute since I used stationary spotlights with CSM

Here is the hotfix list.
5.4.2 Hotfix Released - General / Announcements - Epic Developer Community Forums (unrealengine.com)

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UE5.4.3 hotfix released and yet again broke shadow maps (CSM) when used with instanced stereo. I’ve been updating the above link with information as it is a bug report. I’ve also included a working patch for those needing dynamic shadows for forward rendering with instanced stereo or mobile multiview in forward rendering.

Below is the behavior I’ve outlined for each setting in UE5.4.3 vanilla launcher.
Forward Rendering + instanced stereo (shadows broken in left eye)
Forward Rendering - instanced stereo (shadows working normally)
Deferred Rendering (VSM) + instanced stereo (shadows working normally)
Deferred Rendering (VSM) - instanced stereo (shadows working normally)
Deferred Rendering (CSM) + instanced stereo (Shadows broken in left eye)
Deferred Rendering (CSM) - instanced stereo (Shadows working normally)

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