Spacegraph, A True 3-D Pc Peripheral

The SpaceGraph technology has been packaged as a table-top display station that is a peripheral device for an IBM PC/AT or compatible. It produces 3-D graphics by oscillating the virtual image of a CRT through space while synchronously writing on the screen. In the resulting display volume, one sees a self-luminous, high-contrast, sharp, model-like figure composed of points, lines, and alphanumerics. Optical means include a varifocal plate mirror and a specially designed, large-screen, directed-beam monitor. Electronic means include a controller on a card for an IBM PC/AT or compatible. Software running in the PC allows one to describe a 3-d picture in high-level terms. The controller card can display two pictures at once, and each is double-buffered. A run-time-writable brightness-lookup table takes advantage of 8-bit brightness tags on all 32k displayable points. The software interface is command-driven and includes general and command-specific help. It is capable of getting commands either from files, from the keyboard, or from a combination. Commands take intuitive forms, such as line (3,4,5) (1,2,6) or text (2,4,3) "abc" and locations in space may be given names for convenience of future reference. Additional features are autoscaling, a cursor, and saved display lists. Existing application software can most easily interface to SpaceGraph by writing out files of such commands. An example is the supplied interface to BBN's proprietary software product, RS/1.