Foveated Rendering for VR

[notsofearless]

Sounds promising, or rather more than before.

@notsofearless

I think it works well in flight sims especially, because we want/need extra clarity where we look at tiny instruments, but can get away with cheap bilinear in the periphery.

@mbucchia

When I first released alpha-4 I reached out to a few and asked them to run a special option that captured statistics. Ths results were that the NIS shader was taking something like 700-800 microseconds to run for the full stereo frame. Doing the fixed foveating will reduce that number (less pixels to process), let’s assume it will cut it in half. So ok let’s put us at 400 microseconds. Here’s the thing, saving 400 microseconds per frame at 40 FPS, thats… gaining under 1 FPS. Even if somehow the NIS time is cut to 200 microseconds(!) at 40 FPS this means still just 1 FPS.

So on paper, this does not look promising to me.

To explain the math: at 40 FPS it takes 25ms to render a frame. Remove 400 microseconds from that, thats 24.6ms. Then 1/24.6 = 40.65 FPS.