| 摘要 |
PROBLEM TO BE SOLVED: To correctly judge whether or not a polygon is a projected polygon so as to perform a high-speed paint-out processing or the like by judging whether or not it is the projected polygon by the outer product test and (x) pole and (y) pole vertex tests of the polygon. SOLUTION: A polygon plotting control means 1 judges whether or not the polygon to be plotted is the projected polygon by a projected polygon judgement means 2. A projected polygon judgement processing judges three conditions. A first judgement processing is the outer product test and the codes of the outer products of all adjacent sides are checked. If it is the projected polygon, the outer products of all the adjacent sides are the same code. A second judgement processing is the (x) pole vertex test. The number of the vertexes (x) pole vertexes} for which a displacement direction in an (x) direction is changed of the respective sides is checked and whether or not it is within three pieces is judged. A third judgement processing is the (y) pole vertex test. The number of the vertexes (x) pole vertexes} for which the displacement direction in a (y) direction is changed of the respective sides is checked and whether or not it is within the three pieces is judged. The polygon judged as the projected polygon by first - third judgement conditions is plotted at a high speed by a projected polygon plotting means 3. |
