| 摘要 |
PURPOSE:To obtain a scan converter which can draw an ellipse in a high speed revolution with a small-scale circuit and software. CONSTITUTION:A parameter setting part 10 sets the parameters (longer and shorter diameters, center coordinates) of an unrevolved ellipse, the rotational angle, and the ellipse and straight line DDA(digital differential analyzing) initial values, etc. An elliptic circumference coordinate calculation part 12 turns the unrevolved ellipse into a raster with a DDA operation or applies the scan conversion to the ellipse based on the set value of the part 10. A 1st straight line coordinate calculation part 14 turns a 1st straight line whose slope is defined as the rotational angle of the ellipse into a raster with a DDA operation or applies the scan conversion to the straight line based on the set value of the part 10. A 2nd straight line coordinate calculation part 16 turns a 2nd straight line orthogonal to the 1st straight line into a raster with a DDA operation and applies the scan conversion to the 2nd straight line based on the set value of the part 10. The conditional DDA operations carried out by both parts 14 and 16 are controlled by a coordinate calculation control part 20. |
