| 摘要 |
PURPOSE:To improve memory efficiency and to accelerate computing speed by performing clipping processing after substituting straight lines plotted from upper left to lover right for all the straight lines, and performing plotting after returning a substituted straight line to an original straight line. CONSTITUTION:When a start point X-coordinate is larger than an end point X-coordinate, an X-coordinate position relation information flag is set at an on-state. The clipping processing is performed in an X-axial direction by switching the start point X-coordinate and the end point X-coordinate for a start point Y-coordinate and an end point Y-coordinate. Thence, when the start point Y-coordinate is larger than the end point Y-coordinate, a Y-coordinate position relation information flag is set at the on-state, and the clipping processing in a Y-axial direction is performed similarly by switching the X- coordinate and the Y-coordinate. Thence, when the start point X-coordinate is larger than the end point X-coordinate, the X-coordinate is switched. Finally, the start point and end point of the straight line to be plotted in a view point are found from each coordinate after the clipping processing based on the position relation information flag, then, the plotting is performed. |
