| 摘要 |
PURPOSE:To suppress the increment of useless processing without overlappedly outputting the same vertex in polygons including the vertex existing on a clipping boundary by providing the clipping circuit with a clipping deciding circuit for deciding coordinates to be outputted as a clipped result. CONSTITUTION:An inside/outside deciding circuit 105 decides the positional relation of the coordinates of a vertex of an inputted polygon to the clipping boundary, whether the coordinates are included in the inside or outside or on the boundary. The clipping deciding circuit 109 decides the positional relation of a segment connecting adjacent vertexes with the clipping boundary by using the decided result and an inside/outside deciding result obtained for just preceding vertex precedently inputted and stored in a vertex register 107 and stored in an inside/outside deciding result register 107. If necessary, the coordinates of an intersecting point between a segment calculated by an intersecting point calculating circuit 112 and the clipping boundary and the coordinates of the inputted vertex are outputted through a vertex output circuit 114 in accordance with the positional relation of respective coordinates. Even when another polygon including the same vertex existing in the clipping boundary is inputted, the same vertex is not over-lappedly outputted. |
