project: apply formatting

module.nix: add losslessDLLFile option

default.nix

@@ -1,14 +1,15 @@
-{ lib
+{
-, fetchFromGitHub
+  lib,
-, cmake
+  fetchFromGitHub,
-, ninja
+  cmake,
-, vulkan-headers
+  ninja,
-, vulkan-loader
+  vulkan-headers,
-, llvmPackages
+  vulkan-loader,
-, spirv-headers
+  llvmPackages,
-}: let
+  spirv-headers,
+}:
 
-in llvmPackages.stdenv.mkDerivation {
+llvmPackages.stdenv.mkDerivation {
   pname = "lsfg-vk";
   version = "unstable-2025-07-14-83b869b";
 
@@ -40,6 +41,7 @@ in llvmPackages.stdenv.mkDerivation {
   ];
 
   meta = with lib; {
+    description = "Vulkan layer for frame generation (Requires Lossless Scaling install)";
     homepage = "https://github.com/PancakeTAS/lsfg-vk/";
     license = licenses.mit;
     platforms = platforms.linux;

flake.nix

@@ -1,11 +1,13 @@
 {
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
 
-  outputs = { nixpkgs, ... }: let
+  outputs = { nixpkgs, ... }:
-    system = "x86_64-linux";
+    let
-    pkgs = import nixpkgs { inherit system; };
+      system = "x86_64-linux";
-  in {
+      pkgs = import nixpkgs { inherit system; };
-    packages.${system}.default = pkgs.callPackage ./default.nix {};
+    in
-    nixosModules.default = import ./module.nix;
+    {
-  };
+      packages.${system}.default = pkgs.callPackage ./default.nix { };
+      nixosModules.default = import ./module.nix;
+    };
 }

module.nix

@@ -1,7 +1,12 @@
-{ config, lib, pkgs, ... }:
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
 let
   cfg = config.services.lsfg-vk;
-  lsfg-vk = pkgs.callPackage ./default.nix {};
+  lsfg-vk = pkgs.callPackage ./default.nix { };
 in
 {
   options = {
@@ -13,6 +18,16 @@ in
         description = "The lsfg-vk package to use";
         default = lsfg-vk;
       };
+
+      losslessDLLFile = lib.mkOption {
+        type = with lib.types; nullOr str;
+        default = null;
+        example = "/home/user/games/Lossless Scaling/Lossless.dll";
+        description = ''
+          Sets the LSFG_DLL_PATH environment variable.
+          Required if Lossless Scaling isn't installed in a standard location
+        '';
+      };
     };
   };
 
@@ -22,5 +37,7 @@ in
     # Installs the Vulkan implicit layer system-wide
     environment.etc."vulkan/implicit_layer.d/VkLayer_LS_frame_generation.json".source =
       "${cfg.package}/share/vulkan/implicit_layer.d/VkLayer_LS_frame_generation.json";
+
+    environment.sessionVariables.LSFG_DLL_PATH = lib.mkIf (cfg.losslessDLLFile != null) cfg.losslessDLLFile;
   };
 }