GRASS (programming language): Difference between revisions

Revision as of 14:37, 14 October 2017

Revision as of 17:35, 30 November 2017

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{{about|the programming language|the GIS system|Grass GIS}}

'''GRASS''' (''GRAphics Symbiosis System'') wasis a [[programming language]] created to script [[2D computer graphics|2D]] [[vector graphics]] animations. GRASS was similar to [[BASIC]] in syntax, but added numerous instructions for specifying 2D object animation, including scaling, translation, rotation and color changes over time. It quickly became a hit with the artistic community who were experimenting with the new medium of [[computer graphics]], and will remain most famous for its use by [[Larry Cuba]] to create the original "attacking the [[Death Star]] will not be easy" animation in ''[[Star Wars (film)|Star Wars]]'' (1977). A later version that was adapted to support [[raster graphic]]s was known as '''ZGrass'''.

== History ==

===GRASS===

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With programs constructed from randomly selected modules, Zgrass needed to have better control over its variables than BASIC. In BASIC all variables are "global", so if two subroutines both use the variable <code>i</code> (very common) then they could set each other's values, leading to hard-to-debug problems. Under Zgrass a programmer loading up two modules could easily find that both used i as a loop counter, which could cause problems. To address this issue, Zgrass considered variables named with [[lowercase]] letters to be local only to that macro. Oddly, the examples provided with the language do not make widespread use of this feature, potentially confusing new programmers who might not be aware the feature exists.

== Example ==

SINCURVE=[PROMPT "WHAT IS THE OFFSET?"

INPUT OFFSET