| 摘要 |
PURPOSE:To remarkably curtail the time required for generating an image, by providing a comparing and cumulating circuit on each memory unit, and also, providing an increment circuit for setting an initial value of a depth value and an increment. CONSTITUTION:To each of memory elements MEMi, a comparing and cumulating circuit (I=0-7) consisting of an arithmetic logical arithmetic unit ALUi, a cumulative adder ACCi and a gate Gi is added, and also an increment circuit 3 for setting an initial value of a depth value and increment is provided. The increment circuit 3 sets an initial value of a depth value and an increment of a horizontal line portion to be brought to picture drawing, and supplies them to a comparing and cumulating circuit of each system through a broadcasting bus 4. Each comparing and cumulating circuit executes a cumulative addition of the value, based on a data from the increment circuit 3, by a separate designation, and writes it in the memory element. In such a way, a series of processings such as read-out of a memory at the time of a hidden surface erasion processing, (z) comparision, conditional write and cumulative addition can be executed simultaneously as to an 8-picture element portion in the inside of the memory unit, and the time required for generating an image is remarkably reduced. |
