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Patent Title: Adjustment of Z-buffer values for lines on the surface of a polygon

Assignee: IBM
Patent Number: US5245700
Issue Date: 09-14-1993
Application Number:
File Date:11-21-1989

Abstract: A system and method in a graphics environment ensures that a line drawn upon the surface of a polygon is always visible to a user of the graphics system. In a Z-buffered environment the range of depth values contained therein are set to the 75% of the total capacity which is considered closest to the surface of a display screen. The line is then drawn into this 75% set of Z-buffer depth values. A shift is then computed, based upon the normal to the polygon in device coordinates. This shift is then added to the previously set 75% range of Z-buffer depth values. The polygon is then drawn at a depth equal to the previously set range plus the shift. Thus, the line will always be visible since, the polygon surface will always be considered by a graphics adapter to be deeper than the line contained on the surface thereof.


Link to USPTO

IBM Pledge dated 1/11/2005