Computer graphics dynamic control system

• US 5,061,919 A
• Filed: 05/01/1989
• Issued: 10/29/1991
• Est. Priority Date: 06/29/1987
• Status: Expired due to Term

• Current Assignee: NVIDIA Corporation
• Original Assignee: Evans & Sutherland Computer Corp. (Elevate Entertainment, Inc.)
• Inventors: Watkins, Gary S.
• Primary Examiner(s): Weldon, Ulysses
• Assistant Examiner(s): WU, XIAO MIN
• Application Number:
  US07/345,862
• Time in Patent Office: 911 Days
• Field of Search: 340/721, 340/726, 340/724, 340/723, 340/750, 340/747, 340/799, 340/734, 364/521
• US Class Current: 715/806
• CPC Class Codes: G09G 5/14 Display of multiple viewports
• CPC Class Codes: G09G 5/36 characterised by the display of a graphic pattern, e.g. using an all-points-addressable [APA] memory
• CPC Class Codes: G09G 5/363 Graphics controllers
• CPC Class Codes: G09G 5/39 Control of the bit-mapped memory
• CPC Class Codes: G09G 5/397 Arrangements specially adapted for transferring the contents of two or more bit-mapped memories to the screen simultaneously, e.g. for mixing or overlay G09G5/02 takes precedence
• CPC Class Codes: G09G 5/399 using two or more bit-mapped memories, the operations of which are switched in time, e.g. ping-pong buffers

Abstract

For a raster-scanned, video display apparatus, individual pixel display data is stored in a double image frame buffer. A valid count buffer then holds a count for each pixel. Current valid counts are stored, as at times of image buffer updating which updating includes storing display data changes and a fraction of the total display (background). At times of display, current counts from the count buffer are tested against valid counts as stored for each pixel in the valid count buffer to determine the selection of display data from the image frame buffer or alternate background data. A window frame buffer resolves the display into windows that are accommodated by the system with valid counts for each window.

Claims

1. A dynamic control system for use with a computer graphics apparatus which receives and provides image data and control signals for a scan-pattern display, comprising:

an image frame buffer means for storing pixel area image data for a display;

count means for storing a count for identifying select one of several pixel valid count states;

a storage array for storing pixel valid count representations in relation to said pixel area image data in said image frame buffer means;

comparison means for comparing signals from said count means with signals from said storage array to provide coincidence signals indicating pixel area selections; and

means for controlling said image data with respect to said image frame buffer in accordance with said coincidence signals.

2. A control system according to claim 1 wherein said image frame buffer comprises a double-sided buffer with sides for alternately storing and delivering image data.

3. A control system according to claim 1 wherein said count means comprises means for providing a plurality of counts for selective comparison with said valid count representation.

4. A control system according to claim 1 wherein said storage array comprises means for storing numerical values in a sequence related to the writing of data in said image frame buffer means.

5. A control system according to claim 1 wherein said means for controlling comprises means to input data in said image frame buffer.

6. A control system according to claim 1 wherein said means for controlling comprises means to output data in said image frame buffer.

7. A system according to claim 6 wherein said means to output data comprises means for selectively supplying image data from a pixel section of said image frame buffer means or signals representative of background, determined by the contents of said storage array.

8. A system according to claim 1 further including a window frame buffer for defining plural multiple-area windows of said display and wherein said means for controlling said image data is controlled to some extent by said window frame buffer.

9. A system according to claim 8 wherein said count means stores counts for said windows defined by said window frame buffer.

10. A system according to claim 9 wherein said storage array comprises means for storing said valid count representations for said windows.

11. A control system according to claim 10 wherein said means for controlling comprises means to input data in said image frame buffer.

12. A control system according to claim 10 wherein said means for controlling comprises means to output data in said image frame buffer.

13. In a raster scanned video display apparatus having an image frame buffer which stores display data for a plurality of pixels, the improvement for attaining select different pixel displays including alternative display data, comprising:

storage means for certain of said pixels in said display for storing count signals representing alternate display selections, said storage means being associated with said image frame buffer;

test means for testing said count signals against predetermined count values to indicate a display selection;

table means for supplying said alternative display data;

multiplexer means coupled to receive display data from said image frame buffer and said table means, and controlled by said test means to provide select display data.

14. The improvement defined by claim 13 further including a window frame buffer for storing window signals defining windows in said displays including alternate display data, said window frame buffer being associated with said image frame buffer, said multiplexer further receiving signals from said window frame buffer to provide select display data.

15. A method of displaying a dynamic display from image data comprising the steps of:

defining said display in terms of pixels;

selectively registering display image data for said pixels;

registering count values for said pixels;

testing said count values for said pixels against a current valid count to provide a display selection signal;

providing alternate display image data; and

selecting for display said registered display image data or said alternate display image data under control of said display selection signal.

16. A dynamic control system for use with a computer graphics apparatus which provides image data and control signals for a scan-pattern display, comprising:

an image frame buffer means for storing pixel area image data for said scan-pattern display;

count means for storing a count for identifying select ones of several pixel valid count states;

a storage array for pixel valid count representations in relation to said pixel area image data in said image frame buffer means;

comparison means for comparing signals from said count means with signals from said storage array to provide coincidence signals indicating pixel area selections;

means for writing data in said image frame buffer and related counts in said storage array, for select pixels including a fraction of said pixels designated for background display; and

means for providing data from said image frame buffer under control of said coincidence signals.

17. A system according to claim 16 further including a source of background pixel data and further including means for providing said background pixel data under control of said comparison means.