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Thickened Arc ALGORITHM

IP.com Disclosure Number: IPCOM000060856D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09

Publishing Venue

IBM

Related People

Authors:
Niblett, PD [+details]

Abstract

This article outlines a method of rastering a thickened arc to an all-points-addressable buffer. It is applicable to a graphics display device or to a plotter or printer. The standard method for drawing a thickened arc is to split it into a number of short line segments as if it were unthickened and then to thicken each line individually by drawing another line parallel to it, using some convention based on the angle in which the line is travelling. This approach has the following disadvantages: 1. Wedge-shaped holes may appear where two lines meet, unless the thickening line is carefully extended. 2. Some pels may be drawn more than once. If the arc is drawn in exclusive OR mode (e.g., for dragging across a fixed picture) this causes the pels (picture elements) to disappear and the arc looks ragged (and thinner in places).