OpenGL
OpenGL must break purity due to the need for hardware-specific linkage. Intel, AMD, and Nvidia will have different libraries for example. On NixOS, these libraries are mounted at
/run/opengl-driver/lib
and
/run/opengl-driver-32/lib
When a program is installed in your environment, these libraries should be found automatically. However, this is not the case in a `nix-shell`. To fix, add this line to your shell.nix:
LD_LIBRARY_PATH="/run/opengl-driver/lib:/run/opengl-driver-32/lib";
Testing Mesa updates
To avoid a lot of rebuilds there's an internal NixOS option to override the Mesa drivers: hardware.opengl.package
It can be used like this: hardware.opengl.package = (import /srv/nixpkgs-mesa { }).pkgs.mesa.drivers;
However, since Mesa 21.0.2 this doesn't necessarily work anymore and something like the following might be required:
system.replaceRuntimeDependencies = [
({ original = pkgs.mesa; replacement = (import /srv/nixpkgs-mesa { }).pkgs.mesa; })
({ original = pkgs.mesa.drivers; replacement = (import /srv/nixpkgs-mesa { }).pkgs.mesa.drivers; })
];