GRASS (programming language): Difference between revisions

Revision as of 09:33, 11 February 2017

Revision as of 22:21, 8 March 2017

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===GRASS===

The original version of GRASS was developed by [[Tom DeFanti]] for his 1974 [[Ohio State University]] Ph.D. thesis.{{sfn|DeFanti}} It was developed on a [[PDP-11]]/45 driving a Vector General 3DR display,{{sfn|DeFanti|1980}} and as the name implies, this was a purely [[vector graphics]] machine. GRASS included a number of vector-drawing commands, and could organize collections of them into a hierarchy, applying the various animation effects to whole "trees" of the image at once (stored in arrays).{{sfn|DeFanti|1980}} It was this version that was used for the ''[[Star Wars (film)|Star Wars]]'' animation. If this portion of the film is re-watched, viewers can see object trees popping into the image at various times.

After graduation, DeFanti moved to the [[University of Illinois at Chicago|University of Illinois, Chicago Circle]]. There he joined up with [[Dan Sandin]] and together they formed the ''Circle Graphics Habitat'' (today known as the ''[[Electronic Visualization Laboratory]]'', or EVL). Sandin had joined the university in 1971 and set about building what he thought of as the video version of a [[Moog synthesizer]], known asbuilt the [[Sandin Image Processor]], or IP. The IP was an [[analog computer]] which took two video inputs, mixed them, colored the results, and then re-created TV output. He described it as the video version [[Moog synthesizer]].{{sfn|DeFanti|1980}}

DeFanti added the existing GRASS system as the input to the IP, creating the GRASS/Image Processor, which was used throughout the mid-1970s. In order to make the system more useful, DeFanti and Sandin added all sorts of "one-off" commands to the existing GRASS system, but these changes also made the language considerably more idiosyncratic. In 1977 another member of the Habitat, Nola Donato, re-designed many of GRASS's control structures into more general forms, resulting in the considerably cleaner GRASS3.{{sfn|DeFanti|1980}}

[[Larry Cuba]]'s ''Star Wars'' work is based on a [[rear projection]] filming of a GRASS system running on a vector terminal. As the terminal holds the vectors (and points) in internal memory, the system is able to make basic transformations - scaling, rotation, etc. - in realtime without interacting with the computer or language. It is only during the times when new scenery is being presented that the much slower communications with the GRASS language takes place. This can be seen in the sequence, as the initial sections of the film show the [[Death Star]] being rotated and scaled very rapidly, while the later sections simulating flight down the trench requires new scenery to be paged in from GRASS "trees",. whichThese iscan easilybe visibleseen appearing in groups.

===ZGrass and UV-1===