UG开发三维建模中拉伸的例子。例子比较简单，很容易看懂，这是三维软件开发的基础。弄明白了，再变换成扫描，拔模等命令就很容易了。-UG development of three-dimensional modeling stretch example. Example is relatively simple, easy to understand, this is the basis of three-dimensional software development. Understand, a