UE5.6: Instanced Stereo Rendering Broken for Debug Drawing

Development Platform & Builds XR Development
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Wireframes rendered by debug drawing tools (DrawDebugBox, DrawDebugSphere, etc) are not appearing in both eyes on the device.

In addition, when viewed from within the headset, text that renders for debug print strings is stretched as if trying to draw across both viewports.

This used to work at least in the VR Preview in Unreal 5.5 and was broken when we migrated to 5.6.

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Steps to Reproduce

  1. Create an XR project in Unreal 5.6
  2. Enable forward rendering and instance stereo rendering
  3. In an empty or default map, add in TriggerBox actors into the scene.
  4. Disable HiddenInGame so that the BoxComponents wireframes can be viewed in game.

Steps if Quest HMD is available

  1. Connect a Quest HMD.
  2. If Quest HMD is connected, run VR Preview in the editor. Note the wireframes are not rendering in each eye.
  3. Build a package for Quest and deploy/install to the device. In the headset, run the built package. Note the wireframes are not rendered in each eye.

Steps if No quest is available

  1. If Quest HMD is connected, open the console during the session. Note the console is rendering stretched.
  2. If NO HMD is connected, ensure EmulateStereo is enabled and run a Standalone Game. Note the wireframes are not rendering in each eye.
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Hey! Does this PR solve the issue? https://github.com/EpicGames/UnrealEngine/pull/13528

We’re looking at taking it, but wanted to give you something in the meantime.

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Hi Victor, thanks for the response!

We integrated this change it works nicely for fixing rendering on the Quest3. I was able to verify that the drawing path from UShapeComponent draws were correctly visible and that in development builds, the debug drawing API looked correct.

However, these changes do not appear to affect stereo rendering in the editor, which is something we’re really hoping you can still help us resolve. Specifically, we run VR Preview from the editor using two rendering paths: PC D3D SM6 and Android Generic XR.

We get different results in both cases currently, independent of the integration of the PR:

  • When PC D3D SM6 is enabled, stereo rendering will render both the batched line rendering and the debug drawing API in only one eye.[Image Removed]

  • When Android Generic XR is enabled, stereo rendering works properly for the batched line rendering code path, but the debug drawing API does not render at all.[Image Removed]

Hope this provides some clues that help resolve stereo rendering in the editor.

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Thanks for the detailed info, we’re looking into it - I’ll leave this ticket open until I have a fix to provide you with.

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Hi Victor, any updates on this issue? Posting again to reopen the ticket.

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We have a fix that’s currently awaiting review! I’m sharing a .zip w. the updated source files that you can try out in the meantime. Note that these are for UE5/Main, and may or may not work as-is for UE 5.6.1.