Introduction

I use Linux for laptop. I installed WiVRn and OpenComposite¹ for VR gaming on Linux, as recommended by perillamint.

It works well for Linux native VR programs (e.g. xrgears) and Steam games.

However, it had a problem that non-Steam Windows games don't work.

First try

Steam games works well for VR. Steam uses Proton. Then, How about using Proton for non-Steam games?

umu-launcher

I tried umu-launcher, a program to run Proton for games not in Steam. (Actually, It uses Proton GE, not Proton by Valve. But, it doesn't matter in this post.)

Proton includes OpenXR/VR support. So I expected that it will work well if I set environment variables following SteamVR documentation of WinVR. But it didn't work.

PRESSURE_VESSEL_FILESYSTEMS_RW=/run/user/1000/wivrn/comp_ipc
XR_RUNTIME_JSON=/run/host/usr/share/openxr/1/openxr_wivrn.json

Why?

Reason

After some googling, I found that It needs Steam to be launched to use OpenVR/XR on Proton, and umu launcher doesn't launch Steam by default.

How can I resolve it with minimum efforts?

Solution: Then run Steam :D

Simple. Just run Steam.

Firstly, Let's check where the Proton is. Check debug log by running this command (Type /tmp/2q3ef32t part randomly. It doesn't matter)

UMU_LOG=debug umu-run /tmp/2q3ef32t

Then, you can see the location of proton from the console log. (e.g. /home/foo/.local/share/Steam/compatibilitytools.d/UMU-Proton-9.0-4e/proton) The below is example part of console log.

[umu.umu_run:887] DEBUG: (PosixPath('/home/foo/.local/share/umu/steamrt3/umu'), '--verb', 'waitforexitandrun', '--', PosixPath('/home/foo/.local/share/umu/steamrt3/umu-shim'), PosixPath('/home/foo/.local/share/Steam/compatibilitytools.d/UMU-Proton-9.0-4e/proton'), 'waitforexitandrun', './asdf')

Find this code from the proton file with editor

        # CoD: Black Ops 3 workaround
        if os.environ.get("SteamGameId", 0) in [
                    "311210",   # CoD: Black Ops 3
                    "1549250",  # Undecember
                ]:
            argv = [g_proton.wine_bin, "c:\\Program Files (x86)\\Steam\\steam.exe"]

Replace above code to below.

        if os.environ.get("UMU_RUN_STEAM", 0) == "1":
            argv = [g_proton.wine64_bin, "c:\\windows\\system32\\steam.exe"]
        # CoD: Black Ops 3 workaround
        elif os.environ.get("SteamGameId", 0) in [
                    "311210",   # CoD: Black Ops 3
                    "1549250",  # Undecember
                ]:
            argv = [g_proton.wine_bin, "c:\\Program Files (x86)\\Steam\\steam.exe"]

Finally, Run game UMU_RUN_STEAM environment variable and WiVRn-related environment variables. Check this script for details.

#!/bin/sh
export UMU_RUN_STEAM=1 
export PRESSURE_VESSEL_FILESYSTEMS_RW=/run/user/1000/wivrn/comp_ipc
export XR_RUNTIME_JSON=/run/host/usr/share/openxr/1/openxr_wivrn.json
export PRESSURE_VESSEL_IMPORT_OPENXR_1_RUNTIMES=1
umu-run ./Game.exe

Then It works.

Final words

It's not fundamental solution but simple solution. I wish it could help...