Draft: Nixos support

[RTUnreal]

This PR adds a nix package build via flake.nix.

Due to overte's dependency on node18, this PR is currently blocked until that is updated.
This is due to node18, at least in nixpkgs, requires icu75, but everything else needs icu76. Done

Dependencies/before this PR:

• Fix multiple configuration errors #1781
• Update to libnode 22 LTS. #1711
• Upgrade to Qt6 #1848 (TODO) This will be pushed onto the qt6 branch, when merged
• soft: updated glm can be changed later
• soft: update draco #1808 can be changed later

[RTUnreal]

Also to note as of a week ago, qt5.qtwebengine is marked as insecure, as it contains a lot of unfixed CVEs, due to qt5webengine not being maintained anymore upstream. 1

[JulianGro]

Overte appears to build successfully, but it doesn't start on my machine:

juliangro@x299-workstation ~> export NIXPKGS_ALLOW_INSECURE=1
juliangro@x299-workstation ~> nix --extra-experimental-features flakes --extra-experimental-features nix-command build --impure github:RTUnreal/overte?ref=nixos_support

juliangro@x299-workstation ~> nix --extra-experimental-features flakes --extra-experimental-features nix-command run --impure github:RTUnreal/overte?ref=nixos_support
[12/30 14:18:26] [DEBUG] [hifi.shared] Settings file: "/home/juliangro/.config/Overte - Dev/Interface.json"
[12/30 14:18:26] [DEBUG] [settings.manager] Initializing settings write thread
[12/30 14:18:26] [WARNING] [default] QEventLoop: Cannot be used without QApplication
Gtk-Message: 14:18:26.743: Failed to load module "xapp-gtk3-module"
[12/30 14:18:26] [WARNING] [qt.glx] qglx_findConfig: Failed to finding matching FBConfig for QSurfaceFormat(version 2.0, options QFlags<QSurfaceFormat::FormatOption>(), depthBufferSize -1, redBufferSize 1, greenBufferSize 1, blueBufferSize 1, alphaBufferSize -1, stencilBufferSize -1, samples -1, swapBehavior QSurfaceFormat::SingleBuffer, swapInterval 1, colorSpace QSurfaceFormat::DefaultColorSpace, profile  QSurfaceFormat::NoProfile)
[Previous message was repeated 1 times]
[12/30 14:18:26] [FATAL] [default] Could not initialize GLX
fish: Job 1, 'nix --extra-experimental-featur…' terminated by signal SIGABRT (Abbruch)
juliangro@x299-workstation ~ [SIGABRT]>

I would presume Gtk-Message: 14:18:26.743: Failed to load module "xapp-gtk3-module" to be irrelevant, since it looks similar to other Gtk warnings on Cinnamon.

nix --extra-experimental-features flakes --extra-experimental-features nix-command log --impure github:RTUnreal/overte?ref=nixos_support >> nix.log

nix.log

[RTUnreal]

After looking through opengl docs for NixOS, I remembered, you are not able to just run GL/VK apps from nix on non-nix systems, you would need to either install NixOS and run it there or use a solution like nix-system-graphics1 to run it. (This requires global changes to your system). There is also the nixGL tool2, which wraps the app to use non-nix GL.

I recommend in this order:

1. NixOS
2. NixGL
3. nix-system-graphics

I will also look into more ergonomic ways to test nix stuff on non-nix systems

[JulianGro]

The STEAMWORKS/STEAMCLIENT stuff is the only thing that really needs fixing. Everything else, I don't care too much about, unless we start officially supporting Nix.

[JulianGro]

Why are these defined here, when they were already defined in the unnamed curly braces at the top?

[RTUnreal]

The top is just the function head inside the nix language. When we call pkgs.callPackage from flake.nix, we ask the function to automatically fill in the dependencies as variables for us to use. buildClient for example is just a variable, that can be changed inside of the curly braces in that function call. One can also set specific versions for specific dependencies, like for libv8.

Here we define how the dependencies should be consumed and in which relation, they stand to the overte package, I.e. qt will be required at deployment (buildInputs), but cmake is only only at build time (nativeBuildInputs).

the weird naming is because of legacy code

[JulianGro]

I don't like the "-DOVERTE_BUILD_TYPE=NIGHLTY", but this PR is good to merge from my point of view.

[RTUnreal]

I don't like the "-DOVERTE_BUILD_TYPE=NIGHLTY", but this PR is good to merge from my point of view.

I will add a second PR, which detects, when a build is not in a clean build, so it build it in DEV