Added shell.nix and updated Building.md (#14019)

doc/Building.md

@@ -133,6 +133,15 @@ brew install ccache gettext luacheck p7zip
 export MACOSX_DEPLOYMENT_TARGET=10.09
 ```
 
+### Nix
+
+Ensure the [nix is installed](https://nixos.org/download/).
+
+Then simply run the included nix shell:
+```
+nix-shell tools/shell.nix
+```
+
 ## Getting the source
 
 

tools/shell.nix

@@ -0,0 +1,35 @@
+let
+  nixpkgs = fetchTarball "https://github.com/NixOS/nixpkgs/tarball/nixos-25.05";
+  pkgs = import nixpkgs { config = {}; overlays = []; };
+in
+
+pkgs.mkShell {
+  packages = with pkgs; [
+    autoconf
+    automake
+    libtool
+    cmake
+    gcc
+    git
+    gnumake
+    meson
+    nasm
+    ninja
+    gnupatch
+    perl
+    pkg-config
+    unzip
+    wget
+
+    SDL2
+
+    p7zip
+    ccache
+    gettext
+    luajitPackages.luacheck
+  ];
+
+  shellHook = ''
+    export LD_LIBRARY_PATH=${pkgs.SDL2}/lib:$LD_LIBRARY_PATH
+  '';
+}