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Arc Clipping Algorithm Disclosure Number: IPCOM000060333D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08

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Niblett, PD [+details]


This article describes a method by which an arc rastering routine may be modified to generate an elliptic arc clipped to a rectangular window. The algorithm described here traces around the ellipse, splitting it into visible and invisible segments. THE PROBLEM Various algorithms have been proposed to raster a circular or elliptic arc defined by an analytic equation of the form: ax2 + 2hxy + by2 = ab - h2 about a given center point (here assumed to be integral). The algorithms all operate in a similar manner, tracking around the boundary of the ellipse and causing the appropriate points to be drawn. This article discusses a way in which clipping against a rectangular window may be added to these algorithms.