core/pkgs/by-name/me/mesa/stubs.nix

{ stdenv, libglvnd, mesa, OpenGL, testers }:

stdenv.mkDerivation (finalAttrs: {
  pname = "libGL";
  inherit (if stdenv.hostPlatform.isDarwin then mesa else libglvnd) version;
  outputs = [ "out" "dev" ];

  # On macOS, libglvnd is not supported, so we just use what mesa
  # build. We need to also include OpenGL.framework, and some
  # extra tricks to go along with. We add mesa’s libGLX to support
  # the X extensions to OpenGL.
  buildCommand = if stdenv.hostPlatform.isDarwin then ''
      mkdir -p $out/nix-support $dev
      echo ${OpenGL} >> $out/nix-support/propagated-build-inputs
      ln -s ${mesa.out}/lib $out/lib

      mkdir -p $dev/lib/pkgconfig $dev/nix-support
      echo "$out" > $dev/nix-support/propagated-build-inputs
      ln -s ${mesa.dev}/include $dev/include

      cat <<EOF >$dev/lib/pkgconfig/gl.pc
    Name: gl
    Description: gl library
    Version: ${mesa.version}
    Libs: -L${mesa.out}/lib -lGL
    Cflags: -I${mesa.dev}/include
    EOF

      cat <<EOF >$dev/lib/pkgconfig/glesv1_cm.pc
    Name: glesv1_cm
    Description: glesv1_cm library
    Version: ${mesa.version}
    Libs: -L${mesa.out}/lib -lGLESv1_CM
    Cflags: -I${mesa.dev}/include
    EOF

      cat <<EOF >$dev/lib/pkgconfig/glesv2.pc
    Name: glesv2
    Description: glesv2 library
    Version: ${mesa.version}
    Libs: -L${mesa.out}/lib -lGLESv2
    Cflags: -I${mesa.dev}/include
    EOF
  ''

  # Otherwise, setup gl stubs to use libglvnd.
  else ''
    mkdir -p $out/nix-support
    ln -s ${libglvnd.out}/lib $out/lib

    mkdir -p $dev/{,lib/pkgconfig,nix-support}
    echo "$out ${libglvnd} ${libglvnd.dev}" > $dev/nix-support/propagated-build-inputs
    ln -s ${libglvnd.dev}/include $dev/include

    genPkgConfig() {
      local name="$1"
      local lib="$2"

      cat <<EOF >$dev/lib/pkgconfig/$name.pc
    Name: $name
    Description: $lib library
    Version: ${libglvnd.version}
    Libs: -L${libglvnd.out}/lib -l$lib
    Cflags: -I${libglvnd.dev}/include
    EOF
    }

    genPkgConfig gl GL
    genPkgConfig egl EGL
    genPkgConfig glesv1_cm GLESv1_CM
    genPkgConfig glesv2 GLESv2
  '';

  passthru.tests.pkg-config = testers.testMetaPkgConfig finalAttrs.finalPackage;

  meta = {
    description = "Stub bindings using "
      + (if stdenv.hostPlatform.isDarwin then "mesa" else "libglvnd");
    pkgConfigModules = [ "gl" "egl" "glesv1_cm" "glesv2" ];
  } // {
    inherit (if stdenv.hostPlatform.isDarwin then mesa.meta else libglvnd.meta)
      homepage license platforms;
  };
})