This program runs on all Atari computers, regardless of memory configuration.
This short graphics program draws various patterns on the screen. These patterns are generated by tracing a moving point with straight-line segments. The motion of the point is determined by three numbers provided by the user. These numbers are the rotation angle (R), horizontal-variation factor (VX), and vertical-variation factor (VY). R is a whole number between zero and 359.(the program does not check for invalid input numbers.)
R determines how many lines appear in the drawn pattern. VX (any whole number) creates horizontal variations; VY causes vertical variations.
If the numbers 10, 0 and 0 are entered for R, VX and VY respectively, the resulting drawing will be a circle with 36 straight-line segments. The combination of 60, 0 and 0 creates a hexagon; 144, 0 and 0 result in a five-point star, and so on.
The maximum number of line segments possible in a pattern is 360. This can be produced by entering any prime number for R. When the value for either VX or VY is not zero, the pattern's shape will not be a circle. Instead WHEEL will draw . . . who knows what? Try your favorite numbers and see what happens.
By the way, WHEEL can be easily modified by using Atari Graphics Modes 9, 10 or 11--instead ofGraphics Mode 8-- to achirve interesting color effects.
Jungbo Yang received a B.S degree in computer science in 1978. He is currently employed by CitiCorp in Santa Monica, Calafornia, where he develops software on VAX/ UNIX and other mini/micro systems. Jungbo recently purchased an Atari 800 and is now writing enhanced pattern-generating programs in Forth.
Listing: WHEEL.BAS Download