Not to give the impression that computer graphics always requires a graphics computer, the printout in Fig. 2-35 was produced on a DECwriter teletype printer using a clever BASIC program. The printouts produce a density effect by typing several characters without moving the printhead.


Fig. 2-35. This is a graph of 3-dimensional surface done on a tty printer.

The pattern is a three-dimensional graph of a function, with the Z axis presented as changing density. The program appeared in the November/December 1978 issue of Creative Computing and was written by William Games. This kind of program can be expanded for all kinds of special effects, but requires more programmer sophistication than the graphics-oriented computers described previously.

In the next chapter we will examine several interesting and important ideas of graphics programming.

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