EP0280582A2
Expired / Lapsed
EP
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Improvements in computer graphics systems
Assignee: Axiom Innovation Ltd
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Filing: 1988-02-29
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Granted: —
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Expires: 2008-02-29
Abstract
Abstract A multi-tasking, multiple windowing computer graphics facility which does not place undue burdens upon the processing power of its host computer comprises a multi-planar memory to which data defining windows to be displayed in viewports on a display screen can be written, and a plurality of viewport controllers each individually associated with a respective one of the memory planes and capable of extracting data from each of a plurality of windows defined in its respective memory plane for effecting a corresponding display in any desired viewport location on the display screen. For the management of overlapping viewports, the window-viewport assignments which determine the display locations of viewports on the display screen include viewport priority indications which are taken into account in the reading out of data from the several planes of the multi-planar memory so that overlapping viewports are handled automatically and can appear transparent or opaque relative to one another as required. Windows can be created of any size and any number of planes deep (up to the available depth of the display memory), and opaque or transparent images can be moved freely around the display screen without requiring modification of the data In the memory by flexibly mapping windows in the display memory to viewports on the screen. A VRAM (video RAM), multi-planar memory is used and the viewport controllers are configured as modular VLSI components which can be cascaded for addressing any number of memory planes.
Inventors
- 👤 David John Phillips
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 02:28
CPC Classifications
G; G09; G09G; G09G5/00; G09G5/14
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
80 words
A hardware windowing system for use with a computer graphics facility for deternh l nIng the transfer from a window in memory of image data to be displayed at any chosen viewport location of a display, the hardware windowing system comprising a plurality of viewport controllers each adapted to be individually associated with a single plane of a multi-planar memory for individually processing data transfer from one or more windows in its associated memory plane to viewports in the display.
Claim 2
Dependent Claim
80 words
A hardware windowing system for use with a computer graphics facility for deternh l nIng the transfer from a window in memory of image data to be displayed at any chosen viewport location of a display, the hardware windowing system comprising a plurality of viewport controllers each adapted to be individually associated with a single plane of a multi-planar memory for individually processing data transfer from one or more windows in its associated memory plane to viewports in the display.
Claim 3
Dependent Claim
90 words
A hardware windowing system as claimed in claim 1 wherein each of said plurality of viewport controllers is arranged to be capable of processing data transfer from a plurality of windows in its associated memory plane to viewports in the display, and wherein overlapping viewports are handled by arranging the viewport controllers to be responsive to viewport priority information included in window-viewport mapping assignments provided to the viewport controllers for selectively determining the transfer of image data out of their respective memory planes In accordance with corresponding viewport priority information.
Claim 4
Dependent Claim
48 words
A hardware windowing system as claimed in claim 2 wherein priority control means are provided responsive to the viewport priority information included in the window-viewport mapping assignments provided to the plurality of viewport controllers for determining the display in overlappihg viewports of image data from plural memory planes.
Claim 5
Dependent Claim
60 words
A hardware windowing system as claimed in claim 3 wherein said plurality of viewport controllers are included in a modular cascadable windowing device whereof the priority control means is adapted for communication over a priority bus with the priority control means of one or more other such windowing devices interconnected with the first-mentioned windowing device in a windowing device array.
Claim 6
Dependent Claim
123 words
A hardware windowing system as claimed in claim 4 wherein the priority control means of said windowing device comprises a planar priority control means for handling overlapping viewports deriving from image data stored in windows of the memory planes associated with and controlled by the said windowing device, and a global priority control means coupled with said planar priority control means and adapted to communicate over said priority bus with one or more global control means of other such windowing devices cascaded with the first-mentioned windowing device, the said global priority control means being adapted for handling overlapping viewports deriving from image data stored in windows of memory planes associated with and controlled by different ones of the plurality of cascaded windowing devices.
Claim 7
Dependent Claim
122 words
A hardware windowing system as claimed in any of the preceding claims which is adapted for use with a raster scan computer graphics facility wherein window-viewport mapping assignments are available from a host processor for identifying to the system the required viewport locations of the display and the corresponding window locations in the multi-planar memory, said window-viewport mapping assignments including scan line co-ordinate information relating to viewport and window boundaries and each said viewport controller including means for receiving such viewport boundary scan line co-ordinate information from the host processor on a line-by-line basis, and means responsive to the received viewport boundary scan line co-ordinate information for defining a corresponding address list for use In extracting image data from memory for display.
Claim 8
Dependent Claim
126 words
A hardware windowing system as claimed in claim 6 wherein said window-viewport mapping assignments include for each viewport X i and Y 1 co-ordinates of the top left-hand corner of a rectangular viewport, X 2 and Y 2 co-ordinates of the bottom right-hand corner of the viewport, and Xo and Yo offsets indicative of the X and Y offsets of the corresponding corners of a corresponding window of a memory plane, and said means for defining said address list for use in extracting image data from memory for display is adapted to derive from such co-ordinate information window start addresses in memory and controls for starting and stopping the clocking out of image data from the appropriate memory locations for each scan line of the display.
Claim 9
Dependent Claim
69 words
A hardware windowing system as claimed in claim 7 wherein the window-viewport mapping assignments further include a viewport priority allocation, and said means for defining said address list is adapted to derive said window start addresses and said starting and stopping controls in dependence upon said priority allocations in the event of viewports overlapping on the display, the viewport priorities determining which viewport boundaries will predominate in the display.
Claim 10
Dependent Claim
63 words
A hardware windowing system as claimed in claim 7 or 8 wherein image data is arranged to be clocked out of memory in multi-bit words each corresponding to a plurality of pixels of the display, and the viewport controllers each include logic means for processing the data clocked out of memory so as to obtain single pixel viewport location accuracy in the display.
Claim 11
Dependent Claim
84 words
A hardware windowing system as claimed in claim 8 or 9 and wherein a memory controller is associated with said plurality of viewport controllers and is arranged to be responsive to said controls for organising the extraction of image data from said memory, the arrangement being such that once started the clocking out of image data proceeds until a stop control is received and in between times the memory is accessible for use by a drawing processor for entering fresh image data into memory.
Claim 12
Dependent Claim
31 words
A hardware windowing system as claimed in claim 10 wherein said memory controller includes a handshake interface for enabling co-operation with a drawing processor for time shared utilisation of the memory.
Claim 13
Dependent Claim
95 words
A hardware windowing system as claimed in any of the preceding claims wherein the memory comprises a multi-planar VRAM memory wherein image data is adapted to be stored in multi-bit words each corresponding to a plurality of display pixels, and the viewport controllers are adapted to operate at a speed which is a fraction of the pixel rate of the display but to output a plurality of pixels at a time, the arrangement thereby providing more time for the processing of image data by the viewport controllers without prejudice to the integrity of the display.
Claim 14
Dependent Claim
54 words
A hardware windowing system as claimed in any of the preceding claims adapted for use with a raster scan computer graphics facility and wherein said viewport controllers are adapted and arranged to process the image data required to produce each scan line of the display during the period of the immediately preceding scan line.
Claim 15
Dependent Claim
69 words
A hardware windowing system as claimed in any of the preceding claims wherein four said viewport controllers each capable of independently controlling the display of four windows in a single plane of a multi-planar VRAM memory are assembled together as a VLSI chip, and a single VRAM controller is provided on the chip and serves to provide a control interface between the four viewport controllers and the VRAM memory.
Claim 16
Dependent Claim
153 words
A viewport controller for use in a hardware windowing computer graphics facility for controlling the transfer of image data from a window in a planar memory to a viewport of a raster scan display, said viewport controller being adapted to be responsive to window-viewport mapping assignments provided thereto from a host computer for flexibly mapping windows in memory to viewports of the display and said window-viewport mapping assignments including co-ordinate data X 1 , Yi and X 2 , Y 2 representative of the desired locations in the display of opposed corners of a rectangular viewport and offset data Xo, Yo representative of the offsets in the X and Y directions of the actual locations in memory of the corresponding corners of the window that is required to be displayed in the said viewport from locations defined in memory by the co-ordinate data X 1, Y and X 2 , Y 2 .
Claim 17
Dependent Claim
153 words
A viewport controller for use in a hardware windowing computer graphics facility for controlling the transfer of image data from a window in a planar memory to a viewport of a raster scan display, said viewport controller being adapted to be responsive to window-viewport mapping assignments provided thereto from a host computer for flexibly mapping windows in memory to viewports of the display and said window-viewport mapping assignments including co-ordinate data X 1 , Yi and X 2 , Y 2 representative of the desired locations in the display of opposed corners of a rectangular viewport and offset data Xo, Yo representative of the offsets in the X and Y directions of the actual locations in memory of the corresponding corners of the window that is required to be displayed in the said viewport from locations defined in memory by the co-ordinate data X 1, Y and X 2 , Y 2 .
Claim 18
Dependent Claim
77 words
A viewport controller as claimed in claim 15 and comprising a register for receiving such window-viewport mapping assignments from the host computer, a compiler for processing the data received by the register and deriving therefrom boundary address and associated control signals for each scan line of the display, and a memory controller responsive to the output of the compiler for determining the appropriate extraction of image data from the memory for each scan line of the display.
Claim 19
Dependent Claim
50 words
A viewport controller as claimed in claim 16 wherein said window-viewport mapping assignments further include viewport priority designations for use in the display of overlapping viewports, and said compiler is adapted and arranged to take account of said viewport priority designations in the derivation of said viewport boundary address signals.
Claim 20
Dependent Claim
32 words
A viewport controller as claimed in claim 16 or 17 wherein said memory comprises a VRAM memory, said compiler comprises a VRAM setup list compiler, and said controller comprises a VRAM controller.
Claim 21
Dependent Claim
32 words
A viewport controller as claimed in claim 18 wherein said VRAM controller includes a handshaking interface for determining the sharing of the VRAM memory address and control busses with a drawing processor.
Claim 22
Dependent Claim
67 words
A viewport controller as claimed in claim 18 or 19 wherein the image data is arranged to be clocked out of the VRAM under control of the VRAM controller in the form of data words each corresponding to a plurality of display pixels, and the viewport controller includes means for logically processing the data words output from the VRAM so as to obtain single pixel display accuracy.
Claim 23
Dependent Claim
84 words
A viewport controller as claimed in any of claims 15 to 20 which is adapted and arranged to operate at a pixel rate which is a fraction of the pixel display rate, for providing more time for the internal operations of the viewport controller to be performed, and wherein pixel data is arranged to be output from the viewport controller for display a plurality of pixels at a time to compensate for the reduced pixel rate of the internal operations of the viewport controller.
Claim 24
Dependent Claim
33 words
A viewport controller as claimed in any of claims 15 to 21 which is formed as a VLSI circuit chip and wherein a plurality of such viewport controllers are formed on the chip.
References Cited (Backward Citations)
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