Computer graphics windowing system for the display of multiple dynamic images

• US 4,954,819 A
• Filed: 10/11/1988
• Issued: 09/04/1990
• 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): Oberley, Alvin E.
• Application Number:
  US07/256,335
• Time in Patent Office: 693 Days
• Field of Search: 340/723, 340/724, 340/750, 340/721, 340/734, 340/747, 340/744, 340/799, 364/521
• US Class Current: 345/539
• CPC Class Codes: G09G 5/14 Display of multiple viewports

Abstract

For use in a computer graphics apparatus, a data management system drives a multiple-window dynamic display. The display is formed by areas, e.g. pixels, and windows are variously defined in a display by assigning window codes to groups of areas. Image data for each area provided from a picture system is selectively registered in an image frame buffer in accordance with the defined windows. Valid data binary signals, designating currently valid image data in the image frame buffer are registered in three valid data buffers. The image data for each area is provided for a display from the selectively registered signals in the image frame buffer under control of the window codes and the valid data binary signals. Techniques are thus available for rapidly swapping portions of the frame buffer and selectively clearing and loading the image frame buffer. Areas not specified by signals from the image frame buffer are treated as background and driven with an appropriate display.

Claims

1. A dynamic window control system for use with a computer graphics apparatus, providing 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;

a window frame buffer for defining a plurality of windows of said display;

a plurality of valid data buffers, each for storing a binary validity signal to designate select data pixels as stored in said image frame buffer; and

means for supplying image data from said image frame buffer to said scan-pattern display in the sequence of said scan-pattern selectively under control of said window frame buffer and one of said valid data buffers.

2. A system according to claim 1 wherein said image frame buffer comprises a double frame buffer.

3. A system according to claim 1 wherein said window frame buffer comprises a memory for storing window codes designating individual pixels defining the windows of a composite display.

4. A system according to claim 1 wherein said means for supplying image data selectively supplies background data for areas for which data is not supplied from said image frame buffer means.

5. A system according to claim 1 further including means for writing data to load said image frame buffer comprising means for selecting image data for a specific window controlled by the contents of said window frame buffer.

6. A system according to claim 5 wherein said means for selecting comprises a comparator for testing window code signals from said window frame buffer and signals from a valid data buffer for a select window.

7. A system according to claim 1 wherein said means for supplying image data from said image frame buffer comprises means for alternatively supplying image data from a section of said image frame buffer means or signals representative of background under control of the contents of said window frame buffer, one of said valid data buffers and control signals.

8. A system according to claim 7 wherein said means for supplying image data includes a look-up table and a multiplexer.

9. A system according to claim 7 wherein said valid data buffers comprise three buffer planes.

10. A dynamic window control system for use with a computer graphics apparatus, providing 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;

valid data buffer means for storing validity signals to designate individual data pixels as stored in said image frame buffer;

a window frame buffer including a memory for storing window codes designating individual pixels defining the windows of a composite display; and

means for supplying image data from said image frame buffer to said scan-pattern display in the sequence of said scan-pattern under control of said valid data buffer means and said window frame buffer.

11. A system according to claim 10 wherein said valid data buffer means includes three binary storage buffers.

12. A system according to claim 11 wherein said three binary storage buffers of said valid data buffer means cyclically control the supply of image data to said scan pattern display.

13. A system according to claim 10 further including comparator means controlled by said window frame buffer for loading pixel area image data into said image frame buffer means.