这是一个用tc实现的线段的裁剪算法，但是算法有一点点的漏洞，并不非常完美，这也是为了让初学者不要不经思考就照抄过去-This is a realization of the segment with the tc cut algorithm, but the algorithm has a little bit of vulnerability, is not very perfect, which is not to allow beginners to copy in the past without a thought