split shaders into separate derivation for incremental builds

nix/shaders.nix

@@ -0,0 +1,25 @@
+{
+  lib,
+  stdenvNoCC,
+  qt6,
+}:
+stdenvNoCC.mkDerivation {
+  pname = "nova-shell-shaders";
+  version = "0.1.0";
+
+  src = lib.sourceFilesBySuffices (lib.cleanSource ../shell/modules) [ ".frag" ];
+
+  nativeBuildInputs = [ qt6.qtshadertools ];
+
+  dontBuild = true;
+  dontWrapQtApps = true;
+
+  installPhase = ''
+    runHook preInstall
+    mkdir -p $out/share/nova-shell/modules
+    for f in *.frag; do
+      qsb --qt6 -o "$out/share/nova-shell/modules/''${f}.qsb" "$f"
+    done
+    runHook postInstall
+  '';
+}