How to run bevy game in NixOS?

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1

I came across https://bevyengine.org/ , a game engine in Rust and I want to run their example in NixOS. I am able to compile their example, a reproducible repo with flake support available here for testing:

But right now I am getting this error, despite I am using X11. How can I fix this?

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2

I had something similar with another game engine I wanted to try.

IIRC it was because the library responsible for dynamic loading of drivers used hardcoded pathes.

Back then I didn’t have the time and energy to go deeper than that or even trying to fix, as I wouldn’t have known a portable way to fix it either…

Perhaps you are affected by the same problem?

Check winit and follow how it’s loading the libs.

3

That’s the biggest learning hurdle in NixOS. By default, nothing knows where to find the packages in you the nix store, you must “expose” it within a shell or nix build.

For libX11.so.6, you want the xorg.libX11

$ nix-locate libX11.so.6 --top-level
remarkable2-toolchain.out                             0 s /nix/store/niwh39q61h6s7c127zf0a7291ajjzc6j-remarkable2-toolchain-3.1.2/sysroots/x86_64-codexsdk-linux/usr/lib/libX11.so.6
remarkable2-toolchain.out                     1,285,512 x /nix/store/niwh39q61h6s7c127zf0a7291ajjzc6j-remarkable2-toolchain-3.1.2/sysroots/x86_64-codexsdk-linux/usr/lib/libX11.so.6.3.0
remarkable-toolchain.out                              0 s /nix/store/597yy4hjagq973c07cr347ms84hhq1qw-remarkable-toolchain-3.1.2/sysroots/x86_64-codexsdk-linux/usr/lib/libX11.so.6
remarkable-toolchain.out                      1,285,512 x /nix/store/597yy4hjagq973c07cr347ms84hhq1qw-remarkable-toolchain-3.1.2/sysroots/x86_64-codexsdk-linux/usr/lib/libX11.so.6.3.0
nxproxy.out                                           0 s /nix/store/xr23g4180gb1fvwwcx8kpkdd84fixka3-nx-libs-3.5.99.26/lib/nx/X11/libX11.so.6
nxproxy.out                                           0 s /nix/store/xr23g4180gb1fvwwcx8kpkdd84fixka3-nx-libs-3.5.99.26/lib/nx/X11/libX11.so.6.3.0
xlibs.libX11.out                                      0 s /nix/store/avqk9invc40jg7sh57y0nmpnccz5nm1d-libX11-1.7.2/lib/libX11.so.6
xlibs.libX11.out                              1,433,520 x /nix/store/avqk9invc40jg7sh57y0nmpnccz5nm1d-libX11-1.7.2/lib/libX11.so.6.4.0

(xlibs was the old name)

1 Like
4

You will probably miss other dependencies, here is what I had in a recent bevy project:

  • alsaLib
  • pkgconfig
  • udev
  • vulkan-loader
  • xorg.libX11
  • x11
  • xorg.libXrandr
  • xorg.libXcursor
  • xorg.libXi
2 Likes
5

I thought I am fine already as I am using X11 on my machine already? I thought direnv will just change $PATH, I didn’t realize it will hide shared objects as well

6

Do you mean this rust lib, as it is the lib that interact with X11?

winit - Rust.

7

I’m not sure if it was the one I had trouble with…

8

@Greizgh I have tried to add more deps there, but still I am hitting the same error. can you try and run this one your end and see if you can find anything?

run with cargo run --example breakout

I can confirm that by adding in those dependencies I have fixed that error, but got a new one down below

9

We need some great people to create a starter template in NixOS/template for this …

10

Hm I am now hitting this:

2022-02-03T22:32:28.770646Z  INFO winit::platform_impl::platform::x11::window: Guessed window scale factor: 2.3333333333333335
thread 'main' panicked at 'Unable to find a GPU! Make sure you have installed required drivers!', crates/bevy_render/src/renderer/mod.rs:74:10
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
11

on NixOS, the userland video drivers are mounted to /run/opengl-driver/lib/. Unfortunately, this is kind of a hidden option.

hardware.opengl.enable = true;

related: https://github.com/NixOS/nixpkgs/issues/141803

1 Like
12

I made it working by enabling opengl, and have the following dev shell:

        devShell = with pkgs;
          mkShell {
            nativeBuildInputs = [
              pkgconfig
              clang
              lld # To use lld linker
            ];
            buildInputs = [
              cargo
              rustc
              rustfmt
              pre-commit
              rustPackages.clippy
              alsa-lib
              udev
              #NOTE Add more deps
              vulkan-loader
              xorg.libX11
              x11
              xorg.libXrandr
              xorg.libXcursor
              xorg.libXi
            ];
            shellHook = ''
              export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:${
                pkgs.lib.makeLibraryPath [
                  udev
                  alsaLib
                  vulkan-loader
                ]
              }"'';
            RUST_SRC_PATH = rustPlatform.rustLibSrc;
          };

@NobbZ you might want to give it a try

1 Like