所有的与软件环境无关的函数： 1、点在线上判断 2、确定两条线段是否相交,包括端点 3、求两条线的交点 4、 判断点q是否在多边形Polygon内 等多个函数-All has nothing to do with the software environment of the function: 1, 2-point line on the judge to determine whether two line segments intersect, including th