INFORMATION PROCESSOR AND ITS CONTROL METHOD, AND STORAGE MEDIUM

摘要

PROBLEM TO BE SOLVED: To make an inside/outside decision which is speedily adaptive to any case and eliminates the need to take a ray again and again since the inside/ outside decision is made by using not a rectangle for preliminary inside/outside decision making, but a polygon directly and this invention includes a method which handles a case wherein a side of the polygon matches the ray and a case wherein the side comes into contact with the ray. SOLUTION: It is decided (step S203) whether or not a decision point P meets a vertex Ai, it is decided (step S204) whether the decision point P is on a side AiAi+1, and it is decided (step S205) whether or not the side AiAi+1 and a ray PX have a common point. The number N of inside/outside decisions is increased or decreased (step S206) by deciding an intersection by the position relation between all sides AiAi+1 having a common point and the ray PX. The number N of inside/outside decisions is decided (step S208) and the decision point P is an external point (step S212) when N is 0 and an internal point (step S209) when not.