| 摘要 |
PURPOSE:To omit an unnecessary coordinate conversion and a clip processing, to increase processing speed and to improve the through-put of a device by calculating the existence scope of a primitive included in a segment at a segment unit beforehand. CONSTITUTION:An ALU 21 reads primitive data in a segment header, calculates the maximum and minimum values and makes the average values into central coordinates. The distance between maximum values of central coordinates and X and Y coordinates is obtained as a radious (r) and stored into the segment header. When graphic data are displayed, a converting matrix is prepared from an image converting parameter, next central coordinates and the coordinates on the circular circumference expressed by the radius (r) are calculated, these are given to a multiplier 38 and the matrix multiplication is executed. The area surrounding the circular graphic described by central coordinates and a radius r' approximately adopted after conversion is made into the existence scope after the coordinates are converted, when the scope is in a display area, graphic data are converted, and when the scope is off from the area completely, the coordinate conversion and the clip processing of the graphic data are not executed. |
