Lens Render Issue when using an Overlay in OpenXR-Applications

[Sunoxi]

Description:
Overlays created with the SteamVR-Unity-Plugin break the Lens-Rendering while using the SteamVR-Runtime in OpenXR-Applications. The Rendering to the lenses appears distorted although the Desktop VR-View is not distorted. Inputs all work as if no distortion were present (only visual distortion). Visually the image that is being rendered seems to be rotated and sometimes even mirrored.

Additional Notes:
-The distortion presents differently, depending on the direction the VR-Environment is set up
-After exiting the Overlay-Application the Main-Application stays distorted until restarted.
-SteamVR- and Meta-Menu-Overlays still work fine even while the OpenXR-Application is distorted
-The Sample-Overlay-Scene in the Unity-Plugin also suffers from this Issue.
-When the "Steam VR_Behaviour_Pose" Script is disabled in the sample scene, the distortion does not appear

Steps for Reproduction:

1. Use the SteamVR-Runtime
2. Create a basic Unity project
3. Install the SteamVR-Unity-Plugin v2.8.3
4. Set Application-Type to "Overlay"
5. Open Sample-Scene "Steam VR_First Person Overlay"
6. Start OpenVR-Application (e.g. Beatsaber)
7. Start Unity-Scene
8. In-Game View should now be distorted, Desktop VR-View-Mirror should be unaffected

Tested VR-Devices:
Valve Index: Issue
Varjo Aero: Issue
Oculus Rift S: NO Issue
Meta Quest 3 with Steam-Link connection: Issue
Meta Quest 3 with Air-Link connection: NO Issue

Tested Versions:
-Steam VR Unity Plugin v2.8.3 (sdk 2.5.1)
-Multiple Unity Versions from 2019 onward

All was tested on multiple Windows-Setups with Nvidia GPUs

[kuentzel]

I’ve managed to narrow it down a bit. Sharing here in case it helps others or maintainers:

The distortion seems to come from OpenVR.Compositor.SetTrackingSpace(...).

OpenVR.Compositor.SetTrackingSpace(...) is called in two places in the plugin:

• SteamVR_Action_Pose.SetTrackingUniverseOrigin(...)
• SteamVR_Render.RenderLoop()

When using SteamVR_Behaviour components, a SteamVR_Render gets created automatically when the SteamVR object (SteamVR.Initialize() / SteamVR.InitializeStandalone(), which means the compositor tracking space gets reset every render loop iteration.

In OpenXR standalone apps (e.g., current Beat Saber via SteamLink + Quest), this causes the lens distortion issue.

Workaround I used:
For our project, I patched the plugin to add a conditional around those calls:

if (!SteamVR.isStandalone) {
    OpenVR.Compositor.SetTrackingSpace(newOrigin);
}

This prevents the compositor projection from being misaligned when running a OpenVR Overlay using this Plugin alongside a OpenXR standalone app.

Additional notes:

• Using SteamVR.InitializeStandalone(EVRApplicationType.VRApplication_Overlay) directly doesn’t work here, since the SteamVR_Render loop still runs and triggers OpenVR.Compositor.SetTrackingSpace(...) before SteamVR.isStandalone is set. That also leads to the projection break.
• I’ve also noticed with SteamLink + Quest, opening the SteamVR Dashboard in Beat Saber flips the tracking universe (game rotates 180° around the vertical axis while the dashboard stays correctly oriented). That might be related.

Not sure if this is the right fix, but gating the compositor tracking space updates behind if (!SteamVR.isStandalone) has worked reliably for me. I am using version 2.7.3 but it should be the same for later versions.