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outpostVFX
Participant
October 1, 2015

0.7.0.0 & UE4.9.2 - Vsync clamping

Hi,

I have a scene that is running at a very high framerate in mono rendering, usually doesn't drop below 120fps.

However, when running in the Rift, the framerate appears to be clamped very aggressively. For example, the majority of the scene is running at 75fps (as dictated by the forced vertical sync), but in some areas, the framerate is pulled down to 37.5fps.

I can accept a small FPS drop in more complex areas. But an artificial halving of the framerate is unacceptable. Is there any way to disable this behavior?

Thanks.

EDIT: Just to clarify - changing the PD and SP settings to very low numbers makes no difference. The framerate is always either 75fps, or 37.5fps.
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    1 reply

    vrdaveb
    Inspiring
    October 1, 2015
    In VR, it's very important to use vsync. That means if your frame takes anywhere between 13 and 26 ms to complete, it will get rounded up to 26 while it waits for the next vsync. There is no way to disable this. If there was, it would result in horrible artifacts that would make your users feel nauseous or cross-eyed. If PD has no effect, you probably need to reduce the number of draw calls or triangles. Are you able to get any more detail about your app's performance using the UE4 profiler? See https://docs.unrealengine.com/latest/IN ... index.html
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