Earlier we mentioned that we have been working on DCS VR optimization. I have good news today! After much investigation and work, we traced the issue back to the terrain engine. We have since adjusted the terrain engine, and this has resulted in a 50% increase in VR performance! We will continue to test and optimize this further, but we hope to have this great improvement to you soon.
The DCS engine does a two-pass render, where it effectively draws the scene twice for the stereoscopic view. A lot of games that use Unreal and Unity have moved to a ‘single pass’ where they just draw a larger scene all in one go, but with the left/right views provided like two screens put together. Single pass is often much more efficient.
I wonder if they figured out to single pass view DCS, as maybe it was the terrain engine causing them to do the two pass way. Dunno.
Sounds like a great optimization though, and really timely what with higher resolutions, wider field of views and more detailed graphics all coming down the pipe, VR or not.
Question - how much “worse” would you say VR performance is currently to standard monitors (let’s use 1080p for arguments sake). Does a 50% improvement bring things relatively close? (I understand that VR is outputting a higher total resolution, so would that make it equivalent to the resolution difference.)
VR performance is not really like a monitor performance because it has to provide the frames per second to make the looking around part not slow enough to make you feel ill. A 4k monitor with everything on could be ok to play at 45 fps, but it wouldn’t make you sick. Lag in VR has a threshold where if it goes below the refresh of the screen panels then it’s bad, while normal monitors not so much. Your eyes and balance have to line up, i.e. moving you head and the screen not moving causes motion sickness (one form of it anyway).
I get about 110 fps in DCS 2D 1080p and about 45 fps in 3D with a 2880x1600, more or less. DCS for me is pretty much CPU bound. This optimization if they are only rendering the terrain once, but then copying the scene from left to right view (because you don’t need stereo over a certain distance from the eye) would probably get nearer the magic 90 fps needed for ‘true’ refresh rate of the VR panels.
A lot of people use things like ‘ASW’ and ‘Motion Reprojection’ and that’s the technique where the game only renders 45 fps but the device shows a true 90 fps. It does that by interpolating the scene based on your head movement, i.e. you look a bit left and if a frame isn’t ready to show it ‘shifts’ the last one as if the game did it. Obviously that isn’t perfect but often better than not showing a new frame.These optimizations happen at the VR driver level and DCS doesn’t even know they are happening, just that it needs to provide frames as fast as possible (i.e. at say 50 fps, but not fast enough to draw a new one every 90 fps, so the headset locks it down to 90 / 2 i.e. 45 fps).
This DCS optimization probably won’t get us to 90 fps, but it will provide headroom so that if we’re locked to 45 fps then we can render more detail, more antialiasing (or oversampling, where you provide a resolution higher than the native panel can show, which works like a form of AA) etc, basically make it look better. If it is reaching 60 fps with this optimization, but then locked to 45 fps, then we can add more stuff before it gets close to 45 again.
Hitting 90 every frame in high resolutions is hard, especially in CPU bound things like sims. The HP Reverb which might be our first true ‘clear’ headset other than the Pimax stuff, is a resolution of 4320 x 2160, and that’s without ‘oversampling’ that a lot in VR already use to make things clearer.
You’ve picked a good time this Spring. The new Rift S, the Valve Index and the HP Reverb are all looking great so far. Will be really interesting to see how people get on with those three in DCS, as they all look like upgrades from what we have now in their own way.
I’ll go fetch my O+ out of the trash can now. I was just now looking at monitors because I hate the performance of DCS in vr so much. Great news. Just got a 2080ti and I want DCS to look at least as good as il2 BoX
I’m not sure who advised you to wait, but the Rift has given me three years of amazing experiences in flight simulation. My advice would be to jump on one of these new headsets once they are available. Just remember when choosing your headset that there is more to a good VR experience than just the resolution alone.