| 摘要 |
PURPOSE:To attain a high speed process by generating a frame memory with a polygonal clipping. CONSTITUTION:Three coordinates forming a clipping area on a frame memory 3 are stored on an XON memory 52, an XOFF memory 53, and a Y memory 51, and a prescribed window bit map 1 is scanned setting the inside of a clipping area as a display data, and the data is written on the frame memory 3. In other words, a polygonal area formed with the three coordinate memories restricts only a part where the prescribed window is displayed, and a raster scan control part 2 scans the part as the display data. Therefore, since the parts to be displayed and not to be displayed are distinguished in advance with the clipping area, and when a rewrite is required, it is enough to rewrite only the window, therefore, the generation of the frame memory can be performed faster so much. |
