obs-studio-plugins.obs-vkcapture: enable 32bit support (#188699)

pkgs/applications/video/obs-studio/plugins/default.nix

@@ -1,4 +1,4 @@
-{ callPackage, libsForQt5 }:
+{ callPackage, libsForQt5, pkgsi686Linux }:
 
 {
   obs-gstreamer = callPackage ./obs-gstreamer.nix {};
@@ -10,6 +10,8 @@
   looking-glass-obs = callPackage ./looking-glass-obs.nix {};
   obs-nvfbc = callPackage ./obs-nvfbc.nix {};
   obs-pipewire-audio-capture = callPackage ./obs-pipewire-audio-capture.nix {};
-  obs-vkcapture = callPackage ./obs-vkcapture.nix {};
+  obs-vkcapture = callPackage ./obs-vkcapture.nix {
+    obs-vkcapture32 = pkgsi686Linux.obs-studio-plugins.obs-vkcapture;
+  };
   obs-backgroundremoval = callPackage ./obs-backgroundremoval.nix {};
 }

pkgs/applications/video/obs-studio/plugins/obs-vkcapture.nix

@@ -9,6 +9,7 @@
 , vulkan-headers
 , vulkan-loader
 , libGL
+, obs-vkcapture32
 }:
 
 stdenv.mkDerivation rec {
@@ -22,8 +23,29 @@ stdenv.mkDerivation rec {
     hash = "sha256-yaN0am24p9gC+s64Rop+jQ3952UOtZund/KttnVxP48=";
   };
 
+  cmakeFlags = lib.optionals stdenv.isi686 [
+    # We don't want to build the plugin for 32bit. The library integrates with
+    # the 64bit plugin but it's necessary to be loaded into 32bit games.
+    "-DBUILD_PLUGIN=OFF"
+  ];
+
   nativeBuildInputs = [ cmake ninja ];
-  buildInputs = [ libGL libX11 obs-studio vulkan-headers vulkan-loader wayland ];
+  buildInputs = [
+    libGL
+    libX11
+    vulkan-headers
+    vulkan-loader
+    wayland
+  ]
+  ++ lib.optionals (!stdenv.isi686) [
+    obs-studio
+  ];
+
+  # Support 32bit Vulkan applications by linking in the 32bit Vulkan layer
+  postInstall = lib.optionalString (stdenv.hostPlatform.system == "x86_64-linux") ''
+    ln -s ${obs-vkcapture32}/share/vulkan/implicit_layer.d/obs_vkcapture_32.json \
+      "$out/share/vulkan/implicit_layer.d/"
+  '';
 
   meta = with lib; {
     description = "OBS Linux Vulkan/OpenGL game capture";