Half Life Alyx on Pimax 8KX

[risa2000]

@McUH

There are other calculations though - like the object visibility/clipping, shades and reflections (or other things) calculated in shaders etc. which might still need the camera positions and might not take them into account correctly.

If they do single-pass stereo postprocess/shading the chances are they are doing it to save the performance and will not be probably very thrilled to change that.

[risa2000]

@SweViver

But having PP enabled and lowering the SteamVR SS to 76%, giving us a rendered resolution of 3836x3440 per eye, the game is fully smooth in 75fps so far. And it still looks as good.

The chances are that Valve is using the same VR tech as in SteamVR Home or The Lab, which dynamically adjusts the rendered resolution to meet the refresh rate. If this is the case the recommended render target resolution advertised in SteamVR has no reporting value and the game basically renders at the res it considers the best.

The other consequence is that you should not see a drop in FPS because this is basically what the dynamic res control targets. But you might notice image quality change based on the scene complexity (if it triggers the resolution change).

[SweViver]

@risa2000

The chances are that Valve is using the same VR tech as in SteamVR Home or The Lab, which dynamically adjusts the rendered resolution to meet the refresh rate. If this is the case the recommended render target resolution advertised in SteamVR has no reporting value and the game basically renders at the res it considers the best.

The other consequence is that you should not see a drop in FPS because this is basically what the dynamic res control targets. But you might notice image quality change based on the scene complexity (if it triggers the resolution change).

Yes thats correct. But doing SteamVR SS 100% and PP+NormalFOV, having a reoslution of around 4400 horizontal pixels, there was a lot of frame drops. Sometimes the framerate was just stuck around 70-72. So whenever the dynamic/adaptive resolution works or not, it still dit not make the game smooth, and during these framedrops, I couldnt see any resolution decrease either.

[risa2000]

@SweViver

Sometimes the framerate was just stuck around 70-72. So whenever the dynamic/adaptive resolution works or not, it still dit not make the game smooth, and during these framedrops, I couldnt see any resolution decrease either.

There is a whole video of Alex Vlachos from Valve explaining the adaptive algorithm here (https://www.youtube.com/watch?v=DdL3WC_oBO4). It is a bit more complex than just “changing resolution”, but the resolution is the most visible consequence. It also has its limits (and artificially set tresholds), so it is possible that it does not work perfectly on Pimax, which has much larger FOV than OG Vive or Index.

I guess only Valve devs could explain that.

[SweViver]

@risa2000

There is a whole video of Alex Vlachos from Valve explaining the adaptive algorithm here (https://www.youtube.com/watch?v=DdL3WC_oBO4 ). It is a bit more complex than just “changing resolution”, but the resolution is the most visible consequence. It also has its limits (and artificially set tresholds), so it is possible that it does not work perfectly on Pimax, which has much larger FOV than OG Vive or Index.

I guess only Valve devs could explain that.

Yes I have also noticed the resolution decrease (when it occurs) is only visible in the centre parts of the image and not in the peripherals. It almost looks like reversed FFR on Pimax.

[jojon]

Might be worth mentioning that (playing in an Index, here), I do not see any noticeable whole-screen quality reduction, but I do occasionally see regular LOD/Mipmap popping, as I approach objects, and higher details stream in, including sometimes just a pace or two away… (I should probably reboot ye computer one of these days, to clear out that ol’ fragmented VRAM. :P)

Just in case somebody could confuse the two.