Browse Prior Art Database

Correlation of Coded Graphic Representations With Cursor Position

IP.com Disclosure Number: IPCOM000088749D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Bantz, DF: AUTHOR [+2]

Abstract

Applications systems providing computer graphics facilities are represented by a set of entities, each with a graphical representation. A storage display control system is described for effecting a fast determination of which, if any, application entity has a graphical representation that contains a point sufficiently near a given point. This function, called "graphic comparison" or "correlation," is useful to permit a user of the applications system to designate an entity by moving a cursor to overlay that entity's graphical representation.

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Correlation of Coded Graphic Representations With Cursor Position

Applications systems providing computer graphics facilities are represented by a set of entities, each with a graphical representation. A storage display control system is described for effecting a fast determination of which, if any, application entity has a graphical representation that contains a point sufficiently near a given point. This function, called "graphic comparison" or "correlation," is useful to permit a user of the applications system to designate an entity by moving a cursor to overlay that entity's graphical representation.

The subject system is shown comprised of a digital vector generator 1, two up/down counters (X and Y) 2a and 2b, four digital comparators 3a-d, four adder/subtractors 4a-d, window center registers 5 and 7, window size registers 6 and 8, a logic block 9, and a flip-flop 10. The adder subtractors 4a-d form the window boundaries X +/-(W(x)/2), Y(c)+/-(W(y)/2) and the logic block 9 generates the signal IN on line 1I only if X>/-X(c) -W(x)/2 and X</-X(c) + W(x)/2 and Y>/- Y(c) - W(y)/2 and Y</-Y(c) + W(y)/2 simultaneously. The signal IN is returned to the vector generator 1 to inhibit the generation of the next point when a match occurs, and is also used to set the MATCH flip-flop 10. The signals X and Y may be routed to other hardware (not shown) for display generation.

The subject system enables extremely fast graphic comparison with no ambiguity. The feedback of...