Half Life Alyx on Pimax 8KX

I originally launched the game with PP on and was getting flickering in the lower/outer corners, switching PP off got rid of this. It’s odd that the PP needing to be on is only affecting certain aspects of the game, as my experience when PP is needed you are ‘cross-eyed’ without it. Is this something a PiTool update could fix, or should we ask for Valve support?

2 Likes

Sounds odd.

Well the image is not cross-eyed without PP. It looks normal. But the clipping is there and some shadows and reflections looks strange. Until you enable PP.

The clipping is caused by the game, which on purpose doesn’t render certain objects above 140FOV or so when PP is not used. What PP does is to render the whole game from a different perspective per eye (corrected for canted displays), which means there is a bit more of the peripherals rendered, and luckily, this helps by the fact the clipping happens “outside” of the viewable area of Normal or Large FOV, resulting in no clipping visible.

We can only ask Valve to fix the clipping issue. In Unity engine thats basically 3 lines of code. But Alyx is not made in Unity, so who knows how much work that involves.

4 Likes

By the way, correction:
With PP enabled and SteamVR SS 100%, the framerate can drop down to 68-70fps (unless you enable FFR (conservative at least).
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.

4 Likes

I noticed that without the PP, there is degradation or oddities in certain scenes. So I think it just best to turn PP on and enjoy the game. So far the game is crisp on my 5K+ and works quite good.
I only have: Intel 8700K (~4.6Ghz), 16G memory and NVIDIA 1080TI.

6 Likes

Gotta say the game is amazingly good looking. Not everywhere, but some scenes are insane.

Played for approx 1 hour now. No stutters at all. Smooth 75fps with 3836x3440 per eye and PP enabled. Game settings on Ultra (max). Lovely optimization!

I wonder if VRSS will be supported?

8 Likes

Damn - its the “The way its meant to be played” kind of feeling I get there!

6 Likes

I played smooth in a 1080ti, settings Ultra, Pitool 1.5 and PP in my 5K+. Medium FOV max resolution. Impressive.

8 Likes

Have you downloaded the new Nvidia drivers ?

4 Likes

Same here, although not sure where to find this ULTRA settings.
Like in Half Life 1, I feel I’m the protagonist of the story and everything is new (puzzles and mechanics) and lets face it, we are in the honey moon period of the game, I hope it never ends :grinning:

6 Likes

Its probably the in-game settings, Ultra preset is highest.

3 Likes
1 Like

That is if the different L/R camera angles are not supported at all. Which does not seem to be case here.

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.

Yep, reflections and some shadows are not matching up left/right having PP disabled. Latest Nvidia drivers didnt help. It IS fully playable without PP, but clipping is annoying, especially in down in the serwers where doors clip out and you see a bright texture instead in your peripherals.

Im sure its possible to fix, but its up to Valve to make it happen.

3 Likes

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.

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).

3 Likes

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.

1 Like

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.

3 Likes

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.

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.

2 Likes

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.