Computer graphics processing and selective visual display system – Computer graphics processing – Graph generating
Reexamination Certificate
1998-01-09
2001-09-18
Zimmerman, Mark (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Graph generating
C345S423000
Reexamination Certificate
active
06292192
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to computer graphics, and more particularly to a texture procedure for rendering curved bounded images on a graphics display device.
2. Related Art
A typical computer generated image of a curve bounded object utilizes a number of line segments to approximate the curved boundary. A pixel is a picture element of a graphics display device. Each pixel may represent unique attributes such as color, lighting, texture, etc. As is well known in the relevant art(s), texture procedures may be used to provide visual detail for displayed graphical objects. In a line segment technique, the more line segments used in the representation, the greater accuracy the ultimate display may contain. Each segment may contribute to one or more pixels of the final image. However, the number of line segments that can be used to render a display of a curved bounded region is limited. It is limited by the resolution of the intended graphics display device as well as the available memory space on the computer system. Furthermore, the more line segments used, the greater will be the calculation time, and thus the rendering time.
Conventional textures are image-based and composed of texels, which taken collectively form an image. A polygon is rendered with a mapping specified between the polygon's vertices and the texture. This mapping is usually specified in texture coordinates (s, t). When the polygon is rendered into pixels, the texture coordinates of each pixel are determined and used to lookup a value in the texture that is used in the drawing of the pixel. This value may be color, transparency, etc. Other conventional methods for rendering curved bounded regions have attempted various polygonal approximations and other incremental methods that result in the same limitations described above with respect to line segment techniques. Therefore, what is needed is a texture procedure for rendering curved based objects without the need to convert the graphics object into line segments or perform any type of tessellation.
SUMMARY OF THE INVENTION
The present invention is a system and method for rendering a curve bounded object to a graphics display device directly from a high level curve-based description. The method includes receiving a curve-based description of the graphics object (e.g., character typeface) and dividing the graphics object into a rectangular mesh of texels. Each texel is detailed by defining a combination of curved geometry functions and a boolean function. Each texel contains a miniature resolution independent image of bounded complexity. Taken collectively, the texels form a continuous or resolution independent binary image. The result of the above steps transforms the graphics object into a geometric-texture. The method of the present invention, for each pixel to be displayed, then determines the Cartesian (s, t) coordinate pair within the geometric-texture. The curved geometry functions and the boolean function defined for the texel containing the (s, t) pair are then evaluated. This step is repeated for each (s, t) pair of each pixel of each polygon to be rendered. The result is an alpha value or color for each pixel and thus the display of the curve bounded object to a graphics display device.
In a preferred embodiment, the method of the present invention utilizes two horizontal axis functions, f
0
(s) and f
1
(s), and two vertical axis functions, g
0
(t) and g
1
(t), within each texel in creating the curved geometries.
One advantage of the present invention is that unlike conventional methods that used image-based textures, the invention uses procedural textures that have no inherent resolution and will remain accurate when subject to arbitrary magnification.
Another advantage of the present invention is that the method can be performed using conventional tri-linear interpolation hardware when the curved geometry functions defined for each texel are cubic polynomials.
Another advantage of the present invention is that the method may also be used to implement a class of procedural alpha texture for selectively drawing (trimming) graphic primitives.
REFERENCES:
patent: 4213252 (1980-07-01), Sullivan et al.
patent: 5175806 (1992-12-01), Muskovitz et al.
patent: 5287438 (1994-02-01), Kelleher
patent: 5315537 (1994-05-01), Blacker
patent: 5355449 (1994-10-01), Lung et al.
patent: 5438656 (1995-08-01), Valdes et al.
patent: 5877771 (1999-03-01), Drebin et al.
patent: 5900880 (1999-05-01), Cline et al.
Lorensen (“Geometric Clipping using Boolean Textures”): IEEE1993: ISBN:0-8186-3940-7.
Padmanabhan Mano
Silicon Graphics Inc.
Sterne Kessler Goldstein & Fox PLLC
Zimmerman Mark
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