| 摘要 |
PURPOSE:To draw a circle at a high speed. CONSTITUTION:A circumference registering process means 2a is actuated from an input means 1a and circle information on radii which are high in use frequency are registered. A circle drawing control means 3a checks whether or not circumference information is registered in a circumference address storage means 7a. When the information is registered, a circumference drawing process means 6a is actuated to calculate the address of a circumference by adding the address of the center position of a specified circle on a frame buffer 8a to a relative address registered in the circumference address storage means 7a, thereby writing pixel data in the address. When the information is not registered, on the other hand, a segment developing process means 4a is actuated to approximate the circumference with a polygon and develop it into a segment sequence; and a segment drawing process means 5a is actuated to generate addresses of respective dots on the segments in the segment sequence, thereby writing the pixel data. Thus, the circle with the specified radius is drawn at the indicated position on the frame buffer 8a and displayed on a display device 9a. |
