| 摘要 |
PURPOSE:To easily perform processing by utilizing vertex and side information by repeatedly generating a remaining polygon consisting of vertexes obtained by excluding a twisted vertex from a given polygon, and performing XOR arithmetic with a cut triangle. CONSTITUTION:The polygon A has projection vertexes P1, P2, P4, and P5 and only a recess vertex P3 which is such a twisted vertex that the sides sharing the vertex P3 cross other sides. Therefore, a cut triangle B consisting of the twisted vertex P3 and the vertexes P2 and P4 before and after the vertex P3 is generated. Then, the remaining polygon C consisting of the remaining vertexes except the twisted vertex P3 is generated. The remaining polygon does not contain the twisted vertex, so the cutting process for the triangle is ended and the XOR arithmetic between a quadrangule as the remaining polygon and the cut polygon is performed to obtain an area D. This area is equivalent to the polygon A with the twisted vertex P3 which is painted out so that the vertex information and side information are left. |
