说明：  C++语言编写的几何学算法模板。包括几何学的10多种基本的操作。例如点生成直线，叉积运算，线段的拐向，任意多边形面积的计算，点的位置判断，线段相交判断，求凸包等等。
(C++ Language template geometry algorithm. Including the geometry of more than 10 kinds of basic operation. For example, point to generate a straight line, fork plot computing, the segment拐向, arbitrary polygon area calculations to determine the location of the point, line segment intersection judge, and the convex hull and so on.)