| 摘要 |
PROBLEM TO BE SOLVED: To shorten processing time by specifying the Y (X) axis direction coordinate change judging method following a change in the coordinates in the X (Y) axis direction. SOLUTION: The center coordinates X0, Y0 and radius (r) of a circle are set. Then, a 1st point (X, Y) of circle plotting is found as coordinates from the origin (0, 0) and a change judging reference (e) in the Y axis direction is calculated. Whether a found current coordinate value reaches 1/8 circumference or not is judged in accordance with judgement whether X and Y coordinates reach the segment of X=Y from the origin (0, 0) or not. When the current coordinate value does not reach the 1/8 circumference, coordinates symmetrical about the segment X=Y are found based on the current coordinates and either coordinates symmetrical about X and Y axes formed by using the center coordinate value of two symmetrical coordinates as an origin and the origin (0, 0) are found. When the deviation of the Y (X) axis direction from a value on a real circumference due to the increment (decrement) of the X (Y) axis value is larger than a reference value (e) such as a half of one display, the Y (X) axis value is decreased (increased), so that the deviation of the Y (X) axis value can easily be judged. |
