判断一个点是否在多边形内，绝对正确的算法。C语言

介绍一种自编和经过多年应用考验过的方法--水平射线法，可适用任意复杂多边形，代码简洁，20行搞定，绝对可靠。-Introduction of a self-compiled, and after many years of applications tested by the method- the level of-ray method, applicable to arbitrarily complex polygons, the code simple, 20-line without

判断点是不是在一个矢量图的内部的算法-Judgement is not a vector in the internal algorithm