protonscr

Image Formats IA88 (D3DFMT_A8L8), I8 (D3DFMT_L8) broken

protonclosed
ValveSoftware/Proton#9714 · opened 2026-04-25 by prufaraSS · updated 2026-04-25 · 1 comments · github
PprufaraSS 2026-04-25 github

Compatibility Report

  • Name of the game with compatibility issues: Source Engine/SDK 2013/Garry's Mod
  • Steam AppID of the game: 4000

System Information

  • GPU: Intel Arc B580
  • Video driver version: 26.2.0_devel
  • Kernel version: 6.19.14.zen1-1
  • Link to full system information report as Gist:
  • Proton version: 11 beta

I confirm:

  • [v] that I haven't found an existing compatibility report for this game.
  • [v] that I have checked whether there are updates for my system available.

steam-4000.log

Symptoms

I8(D3DFMT_L8) works as D3DFMT_A8 (shader applies only to alpha channel) (screenshot from Linux with Proton 11):

Image

It should at least fallback to RGBA8888 as provided here (screenshot from Windows system):

Image

D3DFMT_L8 probably should fallback to RGBA8888 too.

Kkisak-valve maintainer 2026-04-25 github

Hello @prufaraSS, we're using one issue report per unofficially supported game title, so I've gone ahead and transferred this issue report to https://github.com/ValveSoftware/Proton/issues/2848#issuecomment-4319967489.

Upstream links