Windows: Rotaded playerspace causes massive latency spikes once app goes out of VR mode (follow-up of #2013)

[XenoPL]

This is a follow-up report on bug #2013 Issue was observerd while running Falcon BMS on Windows 10. Once player exits game 3D world back to UI, latency meter in ALVR-streamer statistics page shows frequent game renderer latency spikes, picture in HMD is not refreshed timely, causing visual glitches on background and whole playerspace does jumps/shifts after every smallest head movement.

Falcon BMS is a flightsim that last year got VR capability, but it still has non-VR user interface. Game starts as 2D window, once player begin actual gameplay it initiates VR mode. According to one of the devs, upon the VR init vr_compositor_->SetTrackingSpace(vr::ETrackingUniverseOrigin::TrackingUniverseSeated) is called. Once player exits game world back to ui, VR mode is closed, game is back to 2D window and then issue can be seen.

Prerequisites to reprouduce bug:

• Falcon 4.0 has to be installed. It's obtainable from Steam or GoG: https://store.steampowered.com/app/429530/Falcon_40/ https://www.gog.com/en/game/falcon_collection
• Falcon BMS 4.37.3 installed free download: https://www.falcon-bms.com/downloads/

Steps to reproduce

• Launch Steam, ALVR and SteamVR on PC and ALVR-client app on the HMD
• Get HMD connected
• click BMS launcher icon to run launcher
• make sure 'Virtual Reality' slider is set to enabled and click 'LAUNCH' button
• In game main UI click on .Dogfight' to open mission window, then click 'Commit' button.
• On mission setup screen click 'TakeOff' button to start actual gameplay
• Hit 'Esc' and 'E' keys on keyboard to end mission and go back to UI.

Expected result: Picture in HMD shows app window and SteamVR background, refreshed properly, head movement tracking is smooth, playerspace stays still. ALVR-streamer statistics show fairly consistent latency with no spikes.

Actual result Picture in HMD is glitchy, and often freezes, playerspace is shifting after head movement. Streaming statistics showw massive latency spikes.

All the symptoms go away once game is closed.

Extra notes: It's possible other apps that have 2D UI and alter playerspace to recenter view are affected. Upcoming BMS 4.37.4 may change behavior as it's migrating to OpenXR from OpenVR API.

Environment

Hardware

CPU: AMD Ryzen 5 5600X GPU: Saphire Radeon 6800 (reference model) GPU Driver Version: AMD Adrenaline 24.2.1

Installation

ALVR Version: 20.6.1 and nightly 20240312 Install Type: Packaged exe and Portable (zip)

SteamVR Version: 2.3.5 and 2.4.3

[github-actions[bot]]

This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[XenoPL]

Any chance somebody will look into this?

[github-actions[bot]]

This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 5 days.