Algorithm for Point in Polygon

The traditional algorithm for checking point in polygon is not convenience,then a convenience algorithm——sloping line method is presented.The characteristic of this algorithm is that the sloping line did not match together with any vertex or edge of polygon,no special situation needs to deal with,the computation time is decreased.First,to make a sloping line from point,and then to count its crossing points with polygon,if the amount of crossing points is odd,then the point is in polygon,otherwise,the point is out of polygon.It is proved that this algorithm is an effective and robust one,and suitable for most cases.