[Gear VR] Engine Changes Requested (for Mobile VR Jam)

[aussieburger]

@;272929

Black creeping in on the edges when turning your head rapidly is normal and expected. There are steps we can take to reduce it further, but it’s expected to be there. The async timewarp is the Oculus code waiting until the very last moment to sample the headset orientation one last time and slide the rendered frame into the very latest position on the screen. This brings in black on the edges where there isn’t information because it was off screen at render time. We could, for example, render with a wider FOV when turning rapidly in order to have a wider frame to sample from in the timewarp, but there are pretty severe perf implications to that which can just make things worse.

What I was referring to as ‘timewarp tearing’ is when you see a vertical shear line in one eye where you see one frame on one side of the line and a following frame on the other. That shouldn’t happen, and is usually caused by taking up too much GPU time in one draw call.

Large translucent draws are usually bad for GearVR perf in general, since overdraw will tend to kill perf. Draw HUD isn’t inherently bad, it just depends on what you do with it. On Note 4 class hardware, you want to touch pixels as few times as possible. Large translucent areas are bad for that.

Great thanks for the explanation and description JJ!