Someone actully made a shader that might be what your looking for.
forums.unrealengine.com/showthread.php?49796-%E3%83%8E%E3%83%B3%E3%83%95%E3%82%A9%E3%83%88%E3%83%AA%E3%82%A2%E3%83%AB%E3%82%84%E3%82%BB%E3%83%AB%E3%83%AB%E3%83%83%E3%82%AF%E7%AD%89%E3%81%AE%E7%8B%AC%E7%89%B9%E3%81%AA%E3%83%AC%E3%83%B3%E3%83%80%E3%83%AA%E3%83%B3%E3%82%B0%E3%82%92%EF%BC%81