Abstract: The present invention is an improved system and method of antialiasing which generates a coverage mask which is retained long enough to achieve geometric precision. The coverage mask information is retained throughout the compositing stage of the image generation. A system for antialiasing an image according to the present invention is comprised of a means for compositing an image, wherein the image is composited using coverage mask data of a pixel, and means for storage of data during image compositing, the storage means coupled to the compositing means.

Abstract: A system for caching texel information in a cache data store, for use in a graphics rendering system which uses interpolative sampling to compute texture color values. The system includes a texel memory storing texel information, a graphics application program for using interpolative sampling to compute dynamic texture values, a first cache data storage for a number of the most-recently-retrieved texels, a second cache data storage for a previously-retrieved adjacent line of texels, cache tag blocks for determining whether the texels needed by the graphics accelerator system are cached in either of the first or second cache data stores, and a memory request generator for retrieving texels from texel memory upon indication of a miss by the cache tag blocks.

Abstract: A computer graphics system having a processor for generating objects for display, a multi-layered Z-buffer for storing data according to their relative depths, the processor also compositing the data stored in the Z-buffer, a frame buffer for storing composited data, a display for displaying an image as a number of pixels responsive to the composited data in the frame buffer, and two registers for facilitating the Z-buffering process is disclosed. One of the registers stores a number indicating how many of the layers in the Z-buffer contain visible data dependent on opacity of existing objects. In the other register, a number of addresses corresponding to each of the layers of the Z-buffer are stored. Each address specifies a location where data of one of the layers is stored. A determination is made as to which layer data associated with an incoming object is to be inserted.

Abstract: A method and apparatus for directly evaluating a parameter interpolation function in a computer graphic system that renders a geometric entity (such as a polygon) by partitioning a display device into a number of local regions. The computer graphic system initially determines that a first set of pixels in a first local region of the display device is covered by a geometric entity. A geometric entity's boundary defining data (e.g., the geometric entity's vertex coordinates defined relative to a display device coordinate system) is employed to generate a local set of coordinates that are defined relative to a first local coordinate system of the first local region for all pixels of the first set of pixels. A first local parameter interpolation function, which represents the parameter values for all pixels of the first set of pixels when these pixels are defined relative to the first local coordinate system, is then generated.

Abstract: A method and apparatus for simultaneous retrieval of multiple pixels from a texture map storage means. Multiple texture maps are generated and stored in a modified M/P (multum in pravo--many things in a small space) map form. Even and odd numbered pixels are stored in different memory banks so that adjacent odd and even pixels may be retrieved simultaneously. The MIP maps are stored so that the pages of the MIP maps having the same resolution are stored contiguously. This arrangement has the effect of reducing the number of unique address signals needed for accessing any two adjacent pixels in the texture map and simplifying the generation of texture map pixel addresses.

Abstract: A method and apparatus for retaining objects having equal Z-values. 1. A method of retaining objects having equal Z-values in a Z-buffer. The Z-buffer includes a first object. The method comprises the steps of: a) receiving a second object having a second Z-value; b) generating a second tag for the second object; c) storing the second object and the second tag in the Z-buffer; d) receiving a third object causing an overflow (the third object has a Z-value equal to the second Z-value); e) generating a fourth object, the fourth object includes a composite of the first and second objects, the fourth object being stored in the Z-buffer with a fourth tag corresponds to the second tag; f) resubmitting the third object; g) receiving the third object; h) generating a third tag for the third object, and i) storing the third object and the third tag in the Z-buffer responsive to comparing the fourth tag and the third tag.

Abstract: A method and apparatus for providing a correctly signed result of a linear interpolation (LIRP) function in a compute controlled display system. A correctly signed LIRP evaluation may be performed by simply adding a bias to each of the operands of the LIRP function and subtracting the bias to the result. Adding the bias is achieved by inverting the high (sign) bit of each of the operands. Subtracting the bias is achieved by inverting the high (sign) bit of the result.

Abstract: An adaptive compression/decompression method for color video data with an anti-aliasing mode. 4.times.4 blocks of pixel data are examined to determine which one of four compression techniques should be used on each block. User settable thresholds can be used to shift the types of compression used. Highest compression is obtained when more data is stored in run length blocks of single colors and lowest compression when more data is stored as two colors with a 32-bit bitmap for each 4.times.4 block. One type of compression used provides anti-aliasing.