Add Nix flake build files

Author: Grumbel

.gitignore

@@ -19,4 +19,5 @@
 /old
 /ruby/flexlay_wrap.so
 /simple/simple
+/result
 moc_*.cpp

flake.lock

@@ -0,0 +1,39 @@
+{
+  description = "SuperTux 0.4.0 level editor";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-21.11";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in rec {
+        packages = flake-utils.lib.flattenTree rec {
+          flexlay = pkgs.python3Packages.buildPythonPackage rec {
+            name = "flexlay";
+            src = self;
+            nativeBuildInputs = [ pkgs.qt5.wrapQtAppsHook ];
+            makeWrapperArgs = [
+              "\${qtWrapperArgs[@]}"
+              "--set" "LIBGL_DRIVERS_PATH" "${pkgs.mesa.drivers}/lib/dri"
+              "--prefix" "LD_LIBRARY_PATH" ":" "${pkgs.mesa.drivers}/lib"
+            ];
+            preCheck = ''
+              export QT_QPA_PLATFORM_PLUGIN_PATH="${pkgs.qt5.qtbase.bin}/lib/qt-${pkgs.qt5.qtbase.version}/plugins";
+            '';
+            propagatedBuildInputs = [
+              pkgs.xorg.libxcb
+              pkgs.p7zip
+              pkgs.python3Packages.setuptools
+              pkgs.python3Packages.numpy
+              pkgs.python3Packages.pyqt5
+              pkgs.python3Packages.pyxdg
+            ];
+          };
+        };
+        defaultPackage = packages.flexlay;
+      });
+}