Computer graphics processing and selective visual display system – Computer graphics processing – Graphic manipulation
Reexamination Certificate
1999-04-28
2001-11-27
Luu, Matthew (Department: 2772)
Computer graphics processing and selective visual display system
Computer graphics processing
Graphic manipulation
C345S501000, C345S204000, C345S581000, C345S215000
Reexamination Certificate
active
06323875
ABSTRACT:
BACKGROUND
1. Technical Field
The present invention relates generally to computer processing systems and, in particular, to a method for rendering display blocks on a display device of a computer processing system.
2. Background Description
FIG. 1
is a block diagram of a display subsystem
100
of a computer processing system according to the prior art. In particular, the display subsystem
100
corresponds to a computer processing system running a Windows NT or other modern operating system. The components of the display subsystem
100
are implemented as a combination of software and hardware.
The display subsystem includes a User Mode and a Kernel Mode. The User Mode includes one or more application programs (hereinafter “application program”)
102
, and an application level interface (API)
104
. The application level interface
104
includes a Graphics Driver Interface (GDI)
104
a
and a Direct Draw (DD) and Direct 3D (D3D) interface (hereinafter collectively referred to as “DD/D3D interfaces”, unless only one of the two is to be described or referred to, in which they shall be respectively referred to as “DD interface” and “D3D interface”, in all cases having the reference character
104
b
).
The Kernel Mode includes a graphics engine (GRE)
106
a
corresponding to the GDI
104
a
, and Kernel mode Direct Draw and Direct 3D layers (hereinafter collectively referred to as “Kernel Mode DD/D3D layers”, unless only one of the two is to be described or referred to, in which they shall be respectively referred to as “Kernel Mode DD layer” and “Kernel Mode D3D layer”, in all cases having the reference character
106
b
) corresponding to the DD/D3D interfaces
104
b.
The Kernel Mode also includes a display driver
108
a
corresponding to the GRE
106
a
, and Direct Draw and Direct 3D drivers (hereinafter collectively referred to as “DD/D3D drivers”, unless only one of the two is to be described or referred to, in which they shall be respectively referred to as “DD driver” and “D3D driver”, in all cases having the reference character
108
b
) corresponding to Kernel Mode DD/D3D layers
106
b
. Moreover, the Kernel Mode includes hardware
110
(e.g., control processor, frame buffer, etc.).
The application program
102
issues drawing commands (e.g. Draw Rectangle) to the GDI
104
a
. In turn, the GDI issues drawing commands, many of which, such as, for example, draw a Dialog box, must be broken down into many graphics primitives. The graphics primitives spawned by the GDI
104
a
are then passed to the GRE
106
a
. The GRE
106
a
calls a defined set of functions in the display driver
108
a
, which implement the graphics primitives spawned by the GDI
104
a.
In addition, the application
102
may issue Direct X commands. With respect to the video subsystem
100
, Direct Draw (DD) and Direct 3D (D3D) commands are of the most interest. To support game manufactures, which required the fastest possible access to the video hardware, the DD interface
104
b
was introduced. The DD interface's main function is to support fast blitting to either the memory buffer (not shown) on the video card or to system memory (not shown). This is typically accomplished by having a front buffer (what the viewer sees) and a series of back buffers. Images are rendered to a back buffer and the back buffer is then flipped to the front buffer which is then seen by the viewer. Though all primitives can be rendered on either the front or back buffer through the standard GDI pipeline as described above, several commands can be directly sent to the DD driver
108
b
. Some examples of these commands are bitblt (copy an image stored in either system memory or display memory to either the front or back buffer), flip (flip the front and back buffers so that the contents of the former back buffer are now viewed), wait for vertical refresh, get the scan line that is being displayed, and so on. Many of these commands allow more direct control of the display hardware
110
than was previously exposed by the Windows architecture. For the bitblt example the coordinates for the source and destination of the image are specified and the filter driver would need to set up and control the off/on screen buffers on several video cards along with any system memory buffers used for graphics. Somewhat different than the GDI case, the command set is a much more low level interface to the graphics hardware. Thus in general, GDI commands usually need to be broken down to several graphics primitives while DD and D3D commands usually do not. This lower software overhead makes DD commands faster than GDI commands.
The D3D interface
104
b
was developed to allow greater performance for 3D graphics. Since 3D programming is much more complicated than DD programming, layers such as Open GL and D3D Retained mode were also developed. These layers are put on top of the D3D layer and the D3D layer is typically referred to as “D3D immediate mode”. In general, the API for Open GL and D3D retained mode is much more application specific while D3D immediate mode is focused on being a low level interface to the 3D graphics hardware. Similar to the GDI
104
a
, an Open GL or D3D Retained mode interface will generally break the command down into one to several D3D immediate mode commands. An example of a D3D immediate mode command would be to set up a specific light (ambient, point, directional, etc.) and use this for the lighting of a scene.
Modern displays adapters implement many GRE, DD, and D3D primitives in hardware to accelerate system graphics. The vendor supplied display driver
108
a
and DD/D3D Drivers
108
b
inform the GRE
106
a
and Kernel Mode DD/D3D layers
106
b
, respectively, of the hardware's capabilities. When a primitive which can be accelerated in hardware is received it is forwarded to these drivers so that they can set up the display hardware
110
to perform the command. In order to know the hardware capabilities of the specific video card there is a list of defined functions and capabilities which the vendor supplied driver can specify that its hardware supports. Many of these capabilities are optional and a few are required. The capabilities are supplied to the GRE
106
a
and Kernel Mode DD/D3D layers
106
b
either when the operating system boots up or when it utilizes those components.
Unfortunately, prior art display subsystems in general, and video display adapters in particular, are designed to address only a maximum fixed number of rows and columns. Therefore, a very large display cannot be addressed by a single video card. Thus, it would be desirable and highly advantageous to have a method for rendering display blocks on a large display of a computer processing system.
SUMMARY OF THE INVENTION
The present invention is directed to a method for rendering display blocks on a display device of a computer processing system.
In one aspect of the invention, there is provided a method for rendering display blocks on a video display device of a computer processing system having an existing display driver. The method includes the step of assigning each of a plurality of n video adapters to an m
th
display subregion of the display device. A call to a draw function supported by the existing display driver is received. The draw function corresponds to a particular shape to be drawn and includes starting and ending coordinates. The m
th
display subregion that drawing of the shape is to begin on is calculated from the starting coordinates. A function of the existing display driver is called by calling an address stored in the filter driver of a routine corresponding to the called function. The called function corresponds to the received draw function. A segment of the shape is rendered on the calculated m
th
display subregion by the n
th
display adapter corresponding thereto. A traversal is made to the n
th
video adapter corresponding to a next segment of the shape. The next segment of the shape is rendered on the m
th
display subregion corresponding to the traversed n
th
video adapter. The traversal and seco
Millman Steven Edward
Warren Kevin Wilson
Chung Daniel J
F. Chau & Associates LLP
International Business Machines - Corporation
Luu Matthew
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