| 摘要 |
PURPOSE:To utilize a efficient data structure that a triangular strip has by outputting a triangle itself when it is decided that a triangle is obtained after the triangle is clipped with a border line, and inserting a dummy vertex and outputting the triangular strip when a quadrangle is obtained. CONSTITUTION:The figure clipping device is provided with an output means 200 which inserts the dummy vertex and outputs the triangular strip when a decision means 100 decides the quadrangle. For example, a vertex (c) which is processed currently and a vertex (a) which are two vertexes precedent are inside the border line 10, a vertex (b) right before the vertex (c) is outside the border line 10, and the quadrangle having four vertexes 1 - 4 is obtained after the triangle is clipped. In this case, the mid-point between the vertexes (a) and (c) positioned inside the border line is outputted as the dummy vertex 5, the intersection of the edge connecting the vertex (c) and vertex (b) and the border line 10 is outputted as a vertex 3, and the vertex (c) is outputted as a vertex 4 lastly to obtain the triangular strip after clipping. Consequently, the efficient data structure that the triangular strip has can be utilized. |
