| 摘要 |
PURPOSE:To additionally draw a picture in a display area without exerting an influence on other area by setting a value of a Z address memory of an optional area among image display areas which have been divided into the plural, to a specific value. CONSTITUTION:A controlling circuit 7 is set to a usual mode for executing a hidden-surface erasion processing by a processor circuit 9, and a forced write mode for writing forcibly a Z address value which has been inputted from a picture element generating circuit 1 to a Z address memory 5. First of all, in order to display an image, all values of the memory 5 are set to Zmax and a graphic is drawn in an image display area. Subsequently, a Z address of an area in which forced picture drawing is executed is set to Zmaz, and graphic data are inputted from the circuit 1. Also, to other area, the data are inputted newly from the circuit 1 and a usual hidden-surface erasion processing is executed. In this way, even if additional picture drawing is executed in the display area, no influence is exerted on other area. |
