Display System Having Floating Point Rasterization and Floating Point Framebuffering

Abstract

A floating point rasterization and frame buffer in a computer system graphics program. The rasterization, fog, lighting, texturing, blending, and antialiasing processes operate on floating point values. In one embodiment, a 16-bit floating point format consisting of one sign bit, ten mantissa bits, and five exponent bits (s10e5), is used to optimize the range and precision afforded by the 16 available bits of information. In other embodiments, the floating point format can be defined in the manner preferred in order to achieve a desired range and precision of the data stored in the frame buffer. The final floating point values corresponding to pixel attributes are stored in a frame buffer and eventually read and drawn for display. The graphics program can operate directly on the data in the frame buffer without losing any of the desired range and precision of the data.

1 . A rendering circuit comprising:
 a geometry processor;   a rasterizer coupled to the geometry processor, the rasterizer comprising a scan converter having an input and an output, the scan converter being configured to scan convert data received at the input, at least a portion of the data received at the input being in floating point format, the scan converter being configured to output data from the output, at least a portion of the data from the output being floating point data; and   a frame buffer coupled to the rasterizer for storing a plurality of color values in floating point format.   
   
   
       2 . The rendering circuit as defined by  claim 1  wherein the scan converter is configured to scan convert on an entirely floating point basis. 
   
   
       3 . The rendering circuit as defined by  claim 1  wherein the data received at the input comprises color data. 
   
   
       4 . The rendering circuit as defined by  claim 1  wherein the rasterizer further includes a floating point texture circuit. 
   
   
       5 . The rendering circuit as defined by  claim 1  wherein the rasterizer operates entirely on a floating point basis. 
   
   
       6 . The rendering circuit as defined by  claim 1  further comprising a circuit board coupled with the geometry processor, rasterizer, and frame buffer. 
   
   
       7 . A rendering circuit comprising:
 a rasterizer for performing a rasterization process, at least a portion of the rasterization process performed in a floating point format; and   a floating point frame buffer coupled to the rasterizer for storing a plurality of floating point color values.   
   
   
       8 . The rendering circuit as defined by  claim 7  wherein the floating point color values are read out from the frame buffer in the floating point format for display. 
   
   
       9 . The rendering circuit as defined by  claim 7  wherein the rasterization process is performed on an entirely floating point basis. 
   
   
       10 . The rendering circuit as defined by  claim 7  wherein the rasterizer comprises an input and an output, the rasterizer configured to process floating point data received at the input, the rasterizer configured to output floating point data at the output. 
   
   
       11 . In a rendering circuit, a method for operating on data stored in a frame buffer, the method comprising:
 storing the data in the frame buffer in a floating point format;   reading the data from the frame buffer in the floating point format; and   writing the data to the frame buffer in the floating point format,   writing, storing, and reading the data in the frame buffer in the floating point format further comprising a specification of the floating point format, wherein the specification corresponds to a level of range and precision.   
   
   
       12 . The method as defined by  claim 11  further comprising operating directly on the data in the floating point format. 
   
   
       13 . The method as defined by  claim 12  wherein storing is performed before reading, reading is performed before operating, and operating is performed before writing. 
   
   
       14 . The method as defined by  claim 11  wherein storing is performed before reading, reading being performed before writing.