Clipping system and method for a graphics processing...

Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension

Reexamination Certificate

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Details

C345S418000

Reexamination Certificate

active

06462737

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to graphics processors and, more particularly, to graphics pipeline systems including transform, lighting and rasterization modules.
BACKGROUND OF THE INVENTION
Three dimensional graphics are central to many applications. For example, computer aided design (CAD) has spurred growth in many industries where computer terminals, cursors, CRT's and graphics terminals are replacing pencil and paper, and computer disks and tapes are replacing drawing vaults. Most, if not all, of these industries have a great need to manipulate and display three-dimensional objects. This has lead to widespread interest and research into methods of modeling, rendering, and displaying three-dimensional objects on a computer screen or other display device. The amount of computations needed to realistically render and display a three-dimensional graphical object, however, remains quite large and true realistic display of three-dimensional objects have largely been limited to high end systems. There is, however, an ever-increasing need for inexpensive systems that can quickly and realistically render and display three dimensional objects.
One industry that has seen a tremendous amount of growth in the last few years is the computer game industry. The current generation of computer games is moving to three-dimensional graphics in an ever increasing fashion. At the same time, the speed of play is being driven faster and faster. This combination has fueled a genuine need for the rapid rendering of three-dimensional graphics in relatively inexpensive systems. In addition to gaming, this need is also fueled by e-Commerce applications, which demand increased multimedia capabilities.
Rendering and displaying three-dimensional graphics typically involves many calculations and computations. For example, to render a three dimensional object, a set of coordinate points or vertices that define the object to be rendered must be formed. Vertices can be joined to form polygons that define the surface of the object to be rendered and displayed. Once the vertices that define an object are formed, the vertices must be transformed from an object or model frame of reference to a world frame of reference and finally to two-dimensional coordinates that can be displayed on a flat display device. Along the way, vertices may be rotated, scaled, eliminated or clipped because they fall outside the viewable area, lit by various lighting schemes, colorized, and so forth. Thus the process of rendering and displaying a three-dimensional object can be computationally intensive and may involve a large number of vertices.
A general system that implements such a pipelined system is illustrated in Prior Art FIG.
1
. In this system, data source
10
generates a stream of expanded vertices defining primitives. These vertices are passed one at a time, through pipelined graphic system
12
via vertex memory
13
for storage purposes. Once the expanded vertices are received from the vertex memory
13
into the pipelined graphic system
12
, the vertices are transformed and lit by a transformation module
14
and a lighting module
16
, respectively, and further clipped and set-up for rendering by a rasterizer
18
, thus generating rendered primitives that are displayed on display device
20
.
During operation, the transform module
14
may be used to perform scaling, rotation, and projection of a set of three dimensional vertices from their local or model coordinates to the two dimensional window that will be used to display the rendered object. The lighting module
16
sets the color and appearance of a vertex based on various lighting schemes, light locations, ambient light levels, materials, and so forth. The rasterization module
18
rasterizes or renders vertices that have previously been transformed and/or lit. The rasterization module
18
renders the object to a rendering target which can be a display device or intermediate hardware or software structure that in turn moves the rendered data to a display device.
When manufacturing graphics processing systems, there is a general need to increase the speed of the various graphics processing components, while minimizing costs. In general, integration is often employed to increase the speed of a system. Integration refers to the incorporation of different processing modules on a single integrated circuit. With such processing modules communicating in a microscopic semiconductor environment, as opposed to external buses, speed is vastly increased.
Integration if often limited, however, by a cost of implementing and manufacturing multiple processing modules on a single chip. In the realm of graphics processing, any attempt to integrate the transform, lighting, and rasterization modules for increased speed would be cost prohibitive. The reason for this increase in cost is that the required integrated circuit would be of a size that is simply too expensive to be feasible.
This size increase is due mainly to the complexity of the various engines. High performance transform and lighting engines alone are very intricate and are thus expensive to implement on-chip, let alone implement with any additional functionality. Further, conventional rasterizers are multifaceted with the tasks of clipping, rendering, etc. making any cost-effective attempt to combine such module with the transform and lighting modules nearly impossible.
There is therefore a need for a transform, lighting, and rasterization module having a design that allows cost-effective integration.
DISCLOSURE OF THE INVENTION
A graphics pipeline system is provided with an integrated clipping operation. First included is a transform module adapted for being coupled to a buffer to receive graphics data therefrom. Such transform module is positioned on a single semiconductor platform for transforming the graphics data from a first space to a second space. Also provided is a lighting module coupled to the transform module and positioned on the same single semiconductor platform as the transform module. The lighting module is adapted for performing lighting operations on the graphics data received from the transform module. A range clamp inversion function and a clipping operation are performed on the same single semiconductor platform as the transform module and the lighting module.
In one embodiment, a rasterizer may be coupled to the lighting module for rendering the graphics data received from the lighting module. Such rasterizer may be positioned on the same single semiconductor platform as the transform module and lighting module.
In another embodiment, the clipping operation may be performed by the rasterizer. It should be noted that the range clamp inverse function may enable the rasterizer to perform the clipping operation. More particularly, the range clamp inverse function may enable the rasterizer to perform the clipping operation by preventing a divide by zero (0).
In still another embodiment, the range clamp inversion function may be performed by the transform module. In particular, the range clamp inversion function may be performed by an inverse logic unit of the transform module.


REFERENCES:
patent: 5886701 (1999-03-01), Chauvin et al.
patent: 5956042 (1999-09-01), Tucker et al.
patent: 6014144 (2000-01-01), Nelson et al.
patent: 6097395 (2000-08-01), Harris et al.
patent: 6137497 (2000-10-01), Strunk et al.
patent: 6163319 (2000-12-01), Peercy et al.
patent: 6342888 (2002-01-01), Lindholm et al.

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