Stereo viewing on the Evans and Sutherland PS350/PS330

Viewing three-dimensional objects in stereo is an indispensable tool in molecular graphics. This paper presents a simple and elegant technique to incorporate stereo in application programs for the Evans and Sutherland PS350 and PS330 equipped with liquid-crystal glasses (Leeds shutters and similar devices). The method makes proper use of the hardware and is not subject to the difficulties encountered with other approaches. We use the time the scope's electron beams need to draw lines for synchronizing with the shutters. Left and right views are alternated in every refresh cycle, rather than requiring at least two. The technique retains the advantages of the PS350 refresh buffer and optimizes the frame-update rate on both machines.