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Claytonious
Up and Coming
January 6, 2017
Solved

Judder and logcat spamming "W/TimeWarp: WarpToScreen: Nothing valid to draw"

  • January 6, 2017
  • 5 replies
  • 1334 views
We're getting this warning spammed to logcat on GearVR while observing horrible view judder on Galaxy S6:

W/TimeWarp: WarpToScreen: Nothing valid to draw


I've seen inconclusive questions about this warning in other threads but they were never definitively answered.

What does this warning mean and what should we *do* to resolve it? Is this a direct result of the recent EGL changes between Oculus/Unity? Is there any workaround? Is this actively being looked into? Is there any news about it?

If you need more details in order to reproduce the problem then I'm happy to provide those, but it seems there are plenty of those already in other threads - the problem is that there are no answers about the problem in any of those.

Thanks!
    This topic has been closed for replies.
    Best answer by vrdaveb
    > The same apk runs at solid 60fps with zero judder on Google daydream with a google pixel phone.

    We have not implemented VR toggling for Gear VR yet. For an APK to work with Gear VR, it has to have Oculus first in the list of supported VR devices and VR must be enabled when the app launches. Can you share the full output of "adb logcat" when you run the APK with Gear VR? Does the issue also occur for a fresh project?

    5 replies

    ClaytoniousAuthor
    Up and Coming
    January 6, 2017
    Thanks for the reply. Since this warning is spewing via logcat every frame, I assumed there was some kind of error in my setup or project configuration, but it sounds like you're saying we simply need to get closer to 60fps. I'll give that a try.

    Thanks!
    vrdaveb
    Inspiring
    January 6, 2017
    > What does this warning mean

    "Nothing valid to draw" means at least one of the buffers used by TimeWarp is not valid. This can happen if Unity hasn't finished rendering to either eye buffer or to an OVROverlay texture.

    >     what should we *do* to resolve it?

    Do you have any OVROverlay instances in your scene? If so, make sure the texture assigned to it is either statically-loaded (a PNG or DXT file) or a RenderTexture that is actually used as a targetTexture by some Camera in the scene.

    If you aren't using OVROverlay and you see valid data in both eye buffers, then there is a chance we have a bug in Unity. It would be nice to know specifically what triggers the spam. Does it go away if you hit frame rate?
    ClaytoniousAuthor
    Up and Coming
    January 7, 2017
    I'll force higher fps by disabling almost everything and let you know.

    No oculus components of any kind in the scene. This is all "unity native" setup.

    The same apk runs at solid 60fps with zero judder on Google daydream with a google pixel phone. Obviously a very different hardware profile there, but it's not that our project is pathologically broken or something.

    Also the judder I'm describing on gear VR isn't simply black bars on the edges - it's as if the entire head is rotating at high frequency. It's deeply broken.

    Thanks for the follow-ups though I will post results of high fps test shortly.
    vrdavebAnswer
    Inspiring
    January 9, 2017
    > The same apk runs at solid 60fps with zero judder on Google daydream with a google pixel phone.

    We have not implemented VR toggling for Gear VR yet. For an APK to work with Gear VR, it has to have Oculus first in the list of supported VR devices and VR must be enabled when the app launches. Can you share the full output of "adb logcat" when you run the APK with Gear VR? Does the issue also occur for a fresh project?
    ClaytoniousAuthor
    Up and Coming
    November 30, 2017
    The issue was peculiar to the beta release of Unity that I was on at that time. It's fine now in 2017.2 and .3 betas.
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