公开(公告)号：US4679041A

公开(公告)日：1987-07-07

申请号：US744496

申请日：1985-06-13

申请人： John L. Fetter ,  Jerald R. Evans ,  Serdar Ergene

发明人： John L. Fetter ,  Jerald R. Evans ,  Serdar Ergene

IPC分类号： G06F17/50 ,  G06T15/40 ,  G09G1/16

CPC分类号： G06T15/405

摘要： The present invention provides apparatus and methods which are most advantageously used in conjunction with a computer display system incorporating the use of a Z-buffer to provide three dimensional hidden surface elimination. A buffer memory is provided which is sufficiently large such that each display element (pixel) on the display is represented by a 16-bit Z value. The Z value corresponds to the Z axis depth of the object at the particular point corresponding to the pixel. The buffer comprises a plurality of dynamic random access memories (D-RAMs) having two operation modes: Normal and Read-Modify-Write (RMW). A counter/pointer register is provided which successively addresses values in the buffer representing successive pixels along scan lines of the display. A graphics processor is provided with coordinates defining a three dimensional image to be displayed and, for each point of the object, computes a current Z.sub.c value beginning at an initial coordinate address in memory. The initial address is loaded into the graphics processor and a D-RAM read-modify write (RMW) cycle is initiated concurrent with the calculation of Z.sub.c. This address corresponds to the address for the point at which the graphics processor is computing Z.sub.c. The value of Z.sub.p, the prior Z value for that address location, is read from the buffer memory and stored in a data-out register. The dynamic RAM in the buffer then waits in the RMW cycle until the processor fetches the Z.sub.p value from the data-out register and compares it to Z.sub.c. The value of Z.sub.p in the buffer is updated if Z.sub.c is less than Z.sub.p. If Z.sub.c is greater than or equal to the Z.sub.p the RMW cycle is aborted, and the current value of Z.sub.p in the buffer is maintained.

摘要翻译： 本发明提供了最有利地与结合使用Z缓冲器以提供三维隐藏表面消除的计算机显示系统结合使用的装置和方法。 提供了足够大的缓冲存储器，使得显示器上的每个显示元件（像素）由16位Z值表示。 Z值对应于与像素对应的特定点处的物体的Z轴深度。 缓冲器包括具有两种操作模式的多个动态随机存取存储器（D-RAM）：正常和读 - 修改 - 写入（RMW）。 提供了一个计数器/指针寄存器，其连续地在表示沿显示器的扫描线的连续像素的缓冲器中寻址。 图形处理器被提供有定义要显示的三维图像的坐标，并且对于对象的每个点，计算从存储器中的初始坐标地址开始的当前Zc值。 初始地址被加载到图形处理器中，并且与Zc的计算同时启动D-RAM读 - 修改写（RMW）周期。 该地址对应于图形处理器计算Zc的点的地址。 从缓冲存储器读取该地址位置的先前Z值的Zp值，并将其存储在数据输出寄存器中。 然后缓冲区中的动态RAM等待RMW周期，直到处理器从数据输出寄存器中取出Zp值并将其与Zc进行比较。 如果Zc小于Zp，则更新缓冲区中的Zp值。 如果Zc大于或等于Zp，则中断RMW周期，并保持缓冲区中当前的Zp值。