anchor.diff:  , enableNvidiaCgToolkit ? false, nvidia_cg_toolkit ? null
   , withVulkan ? stdenv.isLinux, vulkan-loader ? null
   , fetchurl
  +, wayland
  +, libxkbcommon
   }:
   
   with stdenv.lib;
  
positive.code:     rev = "v${version}";
    };
  
    nativeBuildInputs = [ pkgconfig ]
                        ++ optional withVulkan makeWrapper;
  
    buildInputs = [ ffmpeg freetype libxml2 libGLU libGL python3 SDL2 which ]
  
negative.code:                 ++ optional withVulkan vulkan-loader
                  ++ optionals stdenv.isDarwin [ libobjc AppKit Foundation ]
                  ++ optionals stdenv.isLinux [ alsaLib libdrm libpulseaudio libv4l libX11
                                                libXdmcp libXext libXxf86vm mesa udev
                                                wayland libxkbcommon ];
  
    # we use prefix-less pkg-config
    PKG_CONF_PATH = "pkg-config";
  
    enableParallelBuilding = true;
  
  