Z-fighting decals on de_train (Nvidia&AMD, OpenGL&DirectX) on Ultrawide resolutions

[Mershl]

Your system information

• System information from steam: https://gist.github.com/Mershl/05205b8790d1ce3a65ff35578f04141a
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

Decals on flat surfaces are flickering or are only half drawn with visible triangle steps. The issue is best seen on Train, description and video below.

Steps for reproducing this issue:

1. Use the latest LTS Nvidia proprietary driver (440.44)
2. Spawn on Train, fly to Pigeons, zoom down Alley

Issue is reproducible independent of Graphic settings other than resolution.

Tested with OpenGL (native), Windows (DX) and Proton (DXVK).

Video recording of the issue: https://streamable.com/zfeca

Update 1: The issue is also reproducible using the short term branch of the Nvidia driver (435.21).

[Mershl]

After analysis of the Windows and the Linux client I've found a common culprit.

The Z-fighting of decals is only present at Ultrawide resolutions (tested with 3440x1440) on both operation systems.

Reducing the resolution to 1920x1080 shows no flickering, on any decal.

[cubei]

Yeah, totally. But I still no-scope my opponents (and team mates) all the time.

YouCantBringMeDownWithYourBugs #TooSkilledForYou

[Mershl]

@kisak-valve The issue is also reproducible on Windows. On Linux and Windows decals show exactly the same z-fighting on Ultrawidescreen resolutions (3440x1440 tested). Switching to 16:9 resolution fixes the issues on both clients.

[paveltkv]

This bug is reproducible on my system with MSI GTX 1650 SUPER using latest drivers (Windows: 451.67, Ubuntu: 440.100) and ultrawide monitor 2560x1080. This rendering defect can be found not only on de_train, but also on many custom maps. Switching the resolution to 1920x1080 fixes it, but it's definitely not a convenient solution.

[Mershl]

Just replaced my Nvidia card with an AMD+mesa setup. The Z-fighting decals are still visible on Ultrawide resolutions - Windows & Linux.

[TotalEclipse08]

Do we think there might be a solution to this issue other than changing resolution?

[Mershl]

@TotalEclipse08 As this is affecting Windows and Linux as well as Nvidia and AMDGPU it's safe to assume it's a bug in the CS:GO client across all platforms when running on Ultrawide resolution. Unfortunatly we've not received feedback from Valve yet.

[Mershl]

The bug is fixed on Linux using the DXVK/Vulkan renderer introduced yesterday. Decals are correctly rendered at all distances on all tested Ultrawide resolutions. OpenGL (Linux) and DirectX (Windows) are still affected by this issue on Ultrawide resolutions.

[TacoDeBoss]

This bug still occurs on both Vulkan and OpenGL. I can reproduce it on my Steam Deck and PC (R5 5600X/RX 5700XT).