| Abstract: | It is assumed that a host processor computes the corner coordinates of surfaces and outputs these sequentially, in ranked order, to the components described in an OCCAM program. The data is precomputed and stored in a sequential file. A scheduler controls the activity of a number of zone management processors (ZMPs), all running in parallel, and a special memory buffer. Each ZMP handles only one surface at a time. A processor can pick up a new surface for display when the previous surface has been completed. Only one ZMP can write into a given raster scanline at one time. Others may be writing into the same column of other lines at the same time. Hidden surface elimination is achieved by processing the surfaces in an order ranked on distance from the viewing point. This ranking is done in the host processor. The ranked data is held on a file, which is read sequentially in 512 byte blocks. This data has been previously computed and stored as a sequence of double-byte integers in the required order for a series of picture frames, one frame per 512 byte block. The occam implementation on the Apple II europlus running under UCSD version 4 is very slow. It is postulated that an implementation using separate occam professor hardware units for each appropriate process would run in real time. There is considerable communication between the processors. The activity of each processor is generally sequential and all the processors run in parallel. Comments are made about some of the problems and advantages of programming in occam in an appendix. |
