基于VTK平台的一个例子，主要展示了非结构网格的绘制及人机交互的实现，点击四边形的周围的顶点，可以显示一条连接中心点的直线-An example of the platform based on VTK, the main show unstructured grid drawing and realization of human-computer interaction, click the quadrilateral around the vertex, you can display a