| 摘要 |
PURPOSE:To attain simplicity of clipping processing and high speed by omitting the processing relating whether the calculation of an edge point coordinate and an edge point are within the display range or not. CONSTITUTION:Where or not a circle is interlinked in the order of edge lines 5, 6, 7, 8 is discriminated. A perpendicular line is drawn from the center of the circle to a line interlinked at first and the line is used as a reference line 9 (angle 0 deg.). Two angle data are calculated by each edge line and the data is set to an angle table in the ascending order. Angles 10, 11 are processed by an angle calculation section, the angle 10 is set to the angle table 4 and the angle 11 is left to a maximum value storage section. Succeedingly, angles 12, 13 are set after the angle 10 and the angle 11 stored finally is set. The adjacent angle in the angle table finally and only to the data where the relation of thetan<thetan+1 is established, the circular arc display command having a start angle of thetan and an end angle of thetan+1 is formed. |
