System and method for altering an aspect of one of a plurality of coincident visual objects in a video display generator

Claim 1

In a video display system wherein a first visual object is displayed, a second visual object is displayed, part of said second visual object overlaps said first visual object and an overlapping signal is produced to indicate when said overlapping part of said second visual object overlaps said first visual object, a video display generator including a system for altering the color of said overlapping portion of said second visual object comprising: means for generating said first and second visual objects, said first visual object having a first digital word comprising pel values and a second digital word comprising a color collision value associated therewith, and said second visual object having a third digital word comprising color mapping ram data associated therewith which determines the color of said second visual object; means for comparing said first digital word and said second digital word to produce or not produce an enable signal; and means responsive to said enable signal and said overlapping signal for altering said third digital word thereby changing the color of said overlapping portion of said second visual object.