anchor.diff: -{ stdenv, fetchFromGitHub, cmake, mesa, freeglut }:
  +{ stdenv, fetchFromGitHub, cmake, mesa, freeglut, darwin }:
   
   stdenv.mkDerivation rec {
     name = "bullet-${version}";
  
positive.code:     sha256 = "1zz3vs6i5975y9mgb1k1vxrjbf1028v0nc11p646dsvv2vplxx5r";
    };
  
    buildInputs = [ cmake mesa freeglut ];
  
    cmakeFlags = [ "-DBUILD_SHARED_LIBS=ON" "-DBUILD_CPU_DEMOS=OFF" ];
  
    enableParallelBuilding = true;
  
  
negative.code:     description = "A professional free 3D Game Multiphysics Library";
      longDescription = ''
        Bullet 3D Game Multiphysics Library provides state of the art collision
        detection, soft body and rigid body dynamics.
      '';
      homepage = http://code.google.com/p/bullet/;
      license = stdenv.lib.licenses.zlib;
      maintainers = with stdenv.lib.maintainers; [ aforemny ];
      platforms = with stdenv.lib.platforms; unix;
    };
  }
  