anchor.diff:    libX11, libXinerama, libXrandr, libGLU, libGL,
     glib, ilmbase, libxml2, pcre, zlib,
     AGL, Carbon, Cocoa, Foundation,
  +  boost,
     jpegSupport ? true, libjpeg,
     exrSupport ? false, openexr,
     gifSupport ? true, giflib,
  
positive.code:     ++ lib.optional lasSupport libLAS
      ++ lib.optional luaSupport lua
      ++ lib.optional sdlSupport SDL2
      ++ lib.optionals restSupport [ asio boost ]
      ++ lib.optionals withExamples [ fltk wxGTK ]
      ++ lib.optionals stdenv.isDarwin [ AGL Carbon Cocoa Foundation ]
    ;
  
    cmakeFlags = lib.optional (!withApps) "-DBUILD_OSG_APPLICATIONS=OFF" ++ lib.optional withExamples "-DBUILD_OSG_EXAMPLES=ON";
  
negative.code:   lasSupport ? false, libLAS,
    luaSupport ? false, lua,
    sdlSupport ? false, SDL2,
    restSupport ? false, asio,
    withApps ? false,
    withExamples ? false, fltk, wxGTK,
  }:
  