Error: lacking either libGL or libEGL so could not fallback to other

[ClementNerma]

Describe the bug
Getting the following error message when cloning the starter template (https://github.com/emilk/egui_template/) and compiling it with cargo run:

    Finished dev [unoptimized + debuginfo] target(s) in 0.04s
     Running `target/debug/egui_template`
libGL error: No matching fbConfigs or visuals found
libGL error: failed to load driver: swrast
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: GlutinCreationError(CreationErrors([NotSupported("lacking either libGL or libEGL so could not fallback to other"), NoAvailablePixelFormat]))', /home/XXXXXX/.cargo/registry/src/github.com-1ecc6299db9ec823/egui_glium-0.11.0/src/backend.rs:88:85
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

I'm running it on WSL 2 on Windows 10.

I followed the installation instructions and run apt install for all the required packages.

To Reproduce
Steps to reproduce the behavior:

1. Clone the https://github.com/emilk/egui_template/ repository
2. Run cargo run (same result with cargo run --release)

Expected behavior
The example should work fine.

Desktop (please complete the following information):

• OS: Debian 10 on WSL 2 on Windows 10 20H2

[emilk]

Does the examples at https://github.com/rust-windowing/glutin run?

[ClementNerma]

Does the examples at https://github.com/rust-windowing/glutin run?

No, I get the exact same error message.

EDIT: I also tried to install libgl1-mesa-glx just to see and that doesn't change anything

[parasyte]

I haven't tried this myself, but it seems you will need to install a WSLg driver for your GPU: https://devblogs.microsoft.com/commandline/wslg-architecture/#hardware-accelerated-opengl

[ClementNerma]

I haven't tried this myself, but it seems you will need to install a WSLg driver for your GPU: https://devblogs.microsoft.com/commandline/wslg-architecture/#hardware-accelerated-opengl

Unfortunately WSLg isn't available in the stable channel for now. Besides, I think this should work correctly without it as many heavy GUI-based applications work fine with as long as there is an X server running.

[parasyte]

Are you sure it's supposed to work on WSL2 stable? The GUI tutorial says this can only work on Windows 10 Insider Preview build 21362+ as of 2021-04-27.

[ClementNerma]

Are you sure it's supposed to work on WSL2 stable? The GUI tutorial says this can only work on Windows 10 Insider Preview build 21362+ as of 2021-04-27.

As I said, it isn't available as stable for now.

But it's been possible to run GUI applications for a very long time already, by using a third-party X server like Xming.

WSLg is the next step in that direction, allowing to run applications natively on WSL with first-class support without using a third-party server, but it's not available in stable yet.

[parasyte]

There might be some confusion.

An X server on Windows (like Xming or VcXsrv) is a remote X server. This works for the X11 protocol, but not for OpenGL. You will need either a hardware or software rasterizer for OpenGL support in WSL. If you cannot use WSLg (especially its hardware rasterizer), then you might be able to use a software rasterizer like libgl1-mesa-swx11 or gallium llvmpipe.

[ClementNerma]

I see, so in that case it will probably require to wait for WSLg in order for egui to be compatible with WSL at all.

[parasyte]

It depends on the backend you want to use. If you are required to use the egui-glium backend, then yes, you will need OpenGL support. But hypothetically even a TUI backend could be written that will render egui into the terminal. 😉 Or a backend that uses X11; your remote X11 server should work with that.

The trouble is, to my knowledge, none of these backends currently exist.

[ClementNerma]

It depends on the backend you want to use. If you are required to use the egui-glium backend, then yes, you will need OpenGL support. But hypothetically even a TUI backend could be written that will render egui into the terminal. 😉 Or a backend that uses X11; your remote X11 server should work with that.

The trouble is, to my knowledge, none of these backends currently exist.

Ok I understand, so it's more like we'll need WSLg to use the OpenGL backend provided in the examples.

[emilk]

The egui_glium backend has been moved out to a separate repo (https://github.com/fayalalebrun/egui_glium), so I'm gonna close this issue