Shape table
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Shape tables were a powerful yet little-used feature of Applesoft BASIC and Integer BASIC allowing for simple graphic manipulation on Apple II series computers, using the "hi-res" graphics mode.
Each vertice of a two-dimensional graphic was converted into hexadecimal values and those stored via the POKE commands into machine registers. From there, the graphic could be referenced with a variable and built-in Applesoft routines permitted scaling, rotating and moving of the shape, similar to that which is done with geometric modeling software. In fact, shape tables were one of the first implementations of vector graphics on a personal computer.
The idea was that since the manipulation routines were built-in, there would be less of a burden on programmers wanting to develop graphic-heavy programs, such as video games. This would allow for rapid development of new titles and a shortening of the time between concept and release of a new product.
However, shape tables did not catch on with the general programming crowd, and even Apple's developers rarely used them. It may be the fact that since Applesoft BASIC had such a slow processing speed, being an interpreted language, that no one ever considered creating graphic-intensive software with it. Such applications for the Apple II were written in its much faster assembly language. By the time processing speed on the Apple II family had improved, so had the graphics capability (see the Apple IIgs), rendering shape tables obsolete.
Further complicating the use of shape tables was the lack of an included utility or method to create them. Shape tables had to be created by hand, usually by plotting on graph paper, then calculating the hexadecimal values and entering them into the program. Beagle Bros did create a shape table editing program which eliminated the "number crunching" but its use was mostly by hobbyists who had no intention of commercially releasing their programs.
[edit] See also
[edit] External links
- The AppleVision Demo, by Bob Bishop, a demonstration program that used shape tables
- Atariarchives.org example, detailed instructions on assembling shape tables by hand
