Running libGL applications

[bobbbay]

Hi all, I'm developing a project that depends on libGL to launch (using Rust's egui, if it helps). However, when I try to run it, I receive:

thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: CreationErrors([NotSupported("lacking either libGL or libEGL so could not fallback to other"), NotSupported("both libGL and libEGL are not present")])', /home/bob/.cargo/registry/src/github.com-1ecc6299db9ec823/egui_glow-0.17.0/src/epi_backend.rs:29:14
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

I have a working X server, and can run other GUI applications. I'm really unfamiliar with the workings of GUI under-the-hood, which is why I have found no way to resolve this. I have tried adding some (confusingly named) GL libraries to my shell to no avail.

I'm writing this here because it feels less like a bug and more like something I'm doing wrong - I just don't know what it is :).

[nzbr]

glxgears works on Ubuntu but not on NixOS for me - so there might actually be a bug related to graphics acceleration in NixOS-WSL

[bobbbay]

Should I open a bug report, instead?

[shayne]

I ran into something similar a while back and solved my issue by adding: hardware.opengl.enable = true;

[bobbbay]

I wonder if it has anything to do with the following option on my (Windows) X server:

Maybe OpenGL doesn't work because VcXsrv wants to use the Windows-native version instead? But, I just launched it with this option disabled, and get the same error.

[nzbr]

I was assuming that you are using WSLg. I didn't have a good experience using VcXsrv or Xming, so I used X410 before WSLg was a thing

That it works in Ubuntu means that there has to be some way to get this to work, but unfortunately I have no Idea what that may be.
Is using WSLg an option for you?

[bobbbay]

Same thing. Now, it gets weirder: glxinfo looks happy, and spews a bunch of output about my graphics (I assume). glxgears, however, is strange: it outputs on the cli, but no window opens/there is no visual. Last time I checked, it should open up two gears spinning quickly. The output I get is the following:

[nixos@NotYourLaptop:/]$ glxgears
2830 frames in 5.0 seconds = 565.870 FPS
2908 frames in 5.0 seconds = 581.525 FPS
3329 frames in 5.0 seconds = 665.776 FPS
3508 frames in 5.0 seconds = 701.523 FPS
3300 frames in 5.0 seconds = 659.997 FPS
3580 frames in 5.0 seconds = 715.875 FPS
3648 frames in 5.0 seconds = 729.592 FPS
3583 frames in 5.0 seconds = 716.479 FPS
3623 frames in 5.0 seconds = 724.501 FPS
3472 frames in 5.0 seconds = 694.234 FPS
3587 frames in 5.0 seconds = 717.256 FPS
2596 frames in 5.0 seconds = 519.089 FPS
2916 frames in 5.0 seconds = 583.097 FPS
3272 frames in 5.0 seconds = 654.378 FPS
3480 frames in 5.0 seconds = 695.864 FPS
3484 frames in 5.0 seconds = 696.606 FPS
3472 frames in 5.0 seconds = 694.295 FPS
3430 frames in 5.0 seconds = 685.858 FPS
...

Which I imagine is regular output. My laptop fans start going too, so I have a feeling that the graphic acceleration is really being used, I just can't see it (?). Again, not an expert in that area.

[nzbr]

WSLg can be really slow to showing the first window for some reason. Things that can help are

• just waiting (in bad cases even multiple minutes)
• Stopping all instances of the RDP client (mstsc.exe) either in Task Manager or with taskkill /f /im mstsc.exe
• Rebooting Windows
  I have experienced that on other distros as well, so there's probably nothing from the Linux side that can be done

[bobbbay]

Yes, it seems the issue I'm facing is an issue with WSLg (that others have had). Thank you for getting me this far, and I think it's safe to say that if this issue is resolved, libGL on NixOS will be fine. So, I'll close this discussion until further notice 🙂. Thanks again!