Apparatus and method for controlling storage of display information in a computer system

Abstract

A method and apparatus for controlling the storage of display information into a frame buffer is disclosed. A memory means is provided for storing information for controlling the storage of display information into the frame buffer where the memory means contains a plurality of locations each of which corresponds to and controls the storing of display information in one location of the frame buffer. A pass/fail ALU is coupled to the memory means to obtain a value for a particular pixel; this ALU provides a signal indicative of one of a first or second state which state indicates whether storage of display information to the frame buffer will occur. A first function is stored in a register, which function specifies the first signal. A first storage register and a second storage register store a second function and a third function respectively and provide a second value and a third respectively. The second value or third value is stored as a new value in the first memory for said first pixel location depending upon the state indicated by tile first signal. An application of the method and device of the invention includes a method for generating hollow polygons having an interior region and a perimeter in said frame buffer for display on said display device.

Dependencies are inferred from the claim text.