两个凸多边形的交点

For each edge V1-V2 in the first polygon,    Let H := Half-plane tangenting V1-V2, with the remaining        vertices on the "inside".    Let C := New empty polygon.    For each edge V3-V4 in the second polygon,        Let X := The intersection between V3-V4 and H.        If V3 inside H, and V4 is outside H then, Add V3 to C. Add X to C.        Else if both V3 and V4 lies outside H then, Skip.        Else if V3 outside H, and V4 is inside H then, Add X to C.        Else Add V3 to C.    Replace the second polygon with C.

简单的使用就足够了；10-20个顶点，并且不重新计算每一帧。— O（ n 2）

这里是一些链接：

• 计算机图形学I –多边形裁剪和填充（pdf）
• rosettapre.org – Sutherland-Hodgman多边形裁剪