Abstract: A graphics system comprises a texture memory, a rendering engine, a sample buffer and a filtering engine. The rendering engine renders received primitives based on a render pixel array whose vertical and horizontal resolutions are dynamically programmable. The rendering engine determines render pixels that geometrically intersect a primitive. For each intersecting render pixel, a texture access may be required (if texture processing is turned on) to determine texture values. The texture values may be used to compute sample values at sample positions interior to the sample render pixel and the primitive. A controlling agent may decrease the vertical and horizontal resolutions of the render pixel array to control frame render time. The filtering engine may programmably generate virtual pixel centers covering the render pixel array. Any change in the render pixel resolutions may require an accommodating change in the virtual pixel array parameters.

Abstract: A method and computer graphics system for clip testing using clip bits stored in a general-purpose register for each vertex of a geometric primitive. In one embodiment, a rendering unit or other processor sets bits in a clip bits register for each vertex of a geometric primitive. Each bit indicates whether the vertex is inside or outside of a clipping boundary with respect to a particular clipping plane. A frame buffer controller or other graphics processor performs clip testing on the entire geometric primitive by performing Boolean operations on the clip bits. The frame buffer controller may trivially accept or trivially reject the primitive based on the clip testing. If the primitive cannot be trivially rejected or trivially accepted, then the frame buffer controller sends an interrupt to the rendering unit. The rendering unit reads an exception register to determine that the reason for the interrupt is the need to clip the primitive.