OVR submit layers to TimeWarp even frames are discarded.

[daoshengmu]

Fixes #2320. We will get a discard state [1] when WebVR immersive mode is stuck at the content side. That makes us can't continue to get newest controller states until calling vrapi_SubmitFrame2.

[1]

FirefoxReality/app/src/main/cpp/BrowserWorld.cpp

Line 1412 in 9727203

m.device->EndFrame(aDiscardFrame);

[MortimerGoro]

The screen turns black so it breaks the timewarp. We should try to find a way to detect the exit without breaking the TimeWarp effect

[MortimerGoro]

I've tried to reuse the last swapChain and it works but the TimeWarp is not correct either.

[daoshengmu]

Sorry for my unclear comment. This PR is in order to resolve the problem we can’t exit the immersive mode by getting button states when we get stuck at the content side. The actual fix for this demo is supporting Gamepad haptic feedbacks (#2198).

[MortimerGoro]

Yes, the problem is that it breaks the TimeWarp effect. In master if there is a long delay the user sees the last frame Timewarped, but with this change it sees a black screen.

[daoshengmu]

I guess submitting layers with the previous frame index and predictedDisplayTime is what we want. After that, I can see it shows the last frame before the JS crash.

[MortimerGoro]

I have created this sample for testing in Oculus Browser too: https://mortimergoro.github.io/webvr_long_pause/

We should achieve the same behaviour that Oculus Browser does:

• The last used frame is Timewarped (is not black and it doesn't follow the head position)
• Exit from WebVR works

[MortimerGoro]

I found a way to get the desired behavior, PR here: #2341

[daoshengmu]

The more correct fix is available at #2341 now.