A method for the decision of a point whether in or not in self-intersected polygon

In this paper a new method is proposed to decide whether a point is in a polygon, a self-intersected polygon and a ring. A ray is rejected from the test point. According to the position between the edges of polygon and the ray, we define a position function of edges as to the ray, and then count the sum of the position function of all edges. We can decide whether the point is in the polygon, the self-intersected polygon or the ring by the sum. This method applies not only for simple polygon, but also for self-intersected polygon and several simple polygons in the same time. Experiment result indicates that this method is simple, robust and fast.