Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Reexamination Certificate
2000-11-21
2002-06-11
Nguyen, Phu K. (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
Reexamination Certificate
active
06404428
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to vertex information processing in video graphics systems. More particularly, the present invention relates to a method and apparatus for selectively providing drawing commands to the system's graphics processing engine to improve system processing efficiency.
BACKGROUND OF THE INVENTION
Video graphics systems are commonly used to display two-dimensional (2D) and three-dimensional (3D) objects on display devices, such as computer monitors and television screens. Such systems receive drawing commands and object configuration information from software applications, such as video games or Internet browser applications, process the commands based on the object configuration information, and provide appropriate signals to the display devices to illuminate pixels on the device screens, thereby displaying the objects. A block diagram for a typical video graphics system
100
is depicted in FIG.
1
. The video graphics system
100
includes, inter alia, a host processing unit
101
, a peripheral component interconnect (PCI) bus
103
, a graphics processor
105
, memory
107
,
109
and a display device
111
. The graphics processor
105
is typically located on a video card
113
together with local memory
109
that is accessed and used regularly by the graphics processor
105
.
The PCI bus
103
typically includes appropriate hardware to couple the host processing unit
101
to the system memory
107
and the graphics processor
105
, and to couple the graphics processor
105
to the system memory
107
. For example, depending on the system configuration, the PCI bus
103
may include a memory and bus controller integrated circuit (IC) and an accelerated graphics port (AGP) bus to facilitate direct memory access (DMA) transfers of data stored in the system memory
107
to the graphics processor
105
. The display device
111
is typically a conventional cathode ray tube (CRT) display, liquid crystal display (LCD), or other display. Although not shown for purposes of clarity, other components, such as a video frame buffer, a video signal generator, and other known 3D pipeline components, are commonly incorporated between the graphics processor
105
and the display device
111
to properly display objects rendered by the graphics processor
105
.
The host processing unit
101
is typically a central processing unit (CPU) or an equivalent microprocessor-based computer. The host processing unit
101
generally executes several software applications with respect to video graphics processing, including a host application
115
, an operating system runtime layer
117
, and a graphics driver application
119
. These applications
115
-
119
are typically stored on the hard disk component of the system memory
107
, a memory card, a floppy disk, a CD-ROM, or some other computer-readable storage medium. The host application
115
is the application that initiates all drawing commands and provides all information necessary for the other graphics applications and processing components to display objects on the display device
111
. For example, the host application
115
might be a word processing application, a video game, a computer game, a spreadsheet application, or any other application that requires two-dimensional or three-dimensional objects to be displayed on a display device
111
.
In graphics systems, each object to be displayed is typically divided into one or more graphics primitive groups. Common primitive groups include a point list, a line list, and a triangle list. Each primitive group includes a respective number of vertices. For example, a point list primitive group has one or more vertices making up one or more points, a line primitive group has two or more vertices making up one or more lines, and a triangle primitive has three or more vertices making Up one or more triangles. Each vertex has information associated with it to indicate, inter alia, its position in a reference coordinate system and its color. In most applications, such vertex information consists of a vector of multiple parameters to indicate the vertex's position and other optional properties. For example, the vector may include parameters relating to the vertex's normal vector, diffuse color, specular color, other color data, texture coordinates, and fog data. Consequently, the host application
115
not only issues drawing commands, but also provides the vertex information for each vertex of each primitive to be drawn to display each object of a graphics scene.
The operating system runtime layer
117
provides a well-defined application programming interface (API) to the host application
115
and a well-defined device driver interface (DDI) to the graphics driver application
119
. That is, the operating system runtime layer
117
is a software layer that enables various host applications
115
to interface smoothly with various graphics driver applications
119
. One example of an operating system runtime layer application
117
is the “DIRECTX7” component application of the “WINDOWS” family of operating systems that is commercially available from Microsoft Corporation of Redmond, Wash.
The graphics driver application
119
is the application that provides drawing commands to the graphics processor
105
in a manner understandable by the graphics processor
105
. In most circumstances, the graphics driver application
105
and the video card
113
containing the graphics processor
105
are sold as a set to insure proper operation of the graphics rendering portion of the system (i.e., the portion of the graphics system
100
that receives vertex information from the host application
115
, processes the vertex information, and generates the appropriate analog signals to illuminate the pixels of the display device
111
as indicated in the vertex information).
During its execution, the host application
115
stores vertex information in either the system memory
107
or the local memory
109
on the video card
113
. To store the vertex information, the host application
115
first requests allocation of portions of the respective memory
107
,
109
and then stores the vertex information in the allocated portions. The allocated portions of memory
107
,
109
are typically referred to as vertex buffers (VBs)
125
. In addition, the host application
115
stores transformation matrices in either the system memory
107
or the local memory
109
on the video card
113
. The transformation matrices are used by the graphics processor
105
to transform the position vector of each vertex from the so-called “model” coordinate system (i.e., the reference coordinate system used by the application
115
to construct the primitives of the object) to the so-called “eye” or “view” coordinate system (i.e., the coordinate system used to construct objects in the viewing frustum of the display device
111
).
The transformed coordinates in the view coordinate system, or view coordinates, properly position each vertex either inside or outside the viewing frustum of the display device
111
. As is known, the viewing frustum is the theoretical volume in which objects or graphics primitives can be seen by a user when the user views the display device
111
. Thus, the viewing frustum sets the maximum volume in which primitives or objects should be rendered for display by the graphics processor
105
.
Three-dimensional views of typical viewing frustums
201
,
202
are illustrated in FIG.
2
. The first viewing frustum
201
is typically referred to as a viewing frustum with a perspective projection and is in the general shape of a truncated pyramid. When a graphics system
100
uses this viewing frustum, the graphics processor
105
renders objects that are located further from the vantage point of the viewer's eye
203
smaller than objects that are located closer to the viewer's eye
203
. The second viewing frustum
202
is typically referred to as a viewing frustum with an orthographic projection and is generally in the shape of a box or th
Kelley Timothy M.
Radecki Matthew P.
ATI International Srl
Nguyen Phu K.
Vedder Price Kaufman & Kammholz
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