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Display of Images on Vector Graphics Display

IP.com Disclosure Number: IPCOM000087793D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Hughes, MA: AUTHOR [+2]

Abstract

In a vector graphics display apparatus, a graphics processor receives a list of vectors to be displayed. Normally the vector will be identified by its end points. With a raster display, the graphics processor converts the vector list into raster information which is then passed to a refresh buffer. The refresh buffer can be either of the bit-for-pel type in which a complete display frame is stored or, alternatively, may be of the type containing only a raster line. In the latter case the raster information is computed on-the-fly on a line-by-line basis just before it is to be displayed and is loaded into the refresh buffer.

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Display of Images on Vector Graphics Display

In a vector graphics display apparatus, a graphics processor receives a list of vectors to be displayed. Normally the vector will be identified by its end points. With a raster display, the graphics processor converts the vector list into raster information which is then passed to a refresh buffer. The refresh buffer can be either of the bit-for-pel type in which a complete display frame is stored or, alternatively, may be of the type containing only a raster line. In the latter case the raster information is computed on-the-fly on a line-by-line basis just before it is to be displayed and is loaded into the refresh buffer.

The drawing shows how such a vector display can be used to display nonvector information. The drawing shows the format of a Write Rectangle graphic command containing five control fields and one data field of variable length. The meaning of the control fields are as follows:- OP = Operation code to instruct the graphics processor that the command is Write Rectangle. X(W) = Horizontal extent (in bytes) of rectangle. X,Y = Address of top left-hand corner of the rectangle on the screen in picture elements (pels). L =Number of consecutive rows of data, that is, the height of the rectangle, in pels.

The control fields thus command the processor that the immediately following data is to be loaded, unaltered, into the refresh buffer in accordance with the control field parameters. The relationship between...