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Method for Stopping Curve Drawing

IP.com Disclosure Number: IPCOM000065481D
Original Publication Date: 1985-Dec-01
Included in the Prior Art Database: 2005-Feb-19

Publishing Venue

IBM

Related People

Authors:
Iida, H Mamiya, J [+details]

Abstract

A method described here utilizes the characteristic that a quadratic curve does not have two points which have the same inclination to stop the drawing of such a curve. Specifically speaking, an X coordinate and an octant signal are used to stop the drawing of the curve. The octant signal has 8 different values, as shown in Fig. 1. In case the drawing of a circle should be stopped at a point B (Fig. 2), an X coordinate of the point B and a octant value=101 are stored. Then, if an X coordinate and an octant signal generated during the drawing of the circle are matched with the X coordinate and the octant value, respectively, the drawing is stopped. Point A has the same X coordinate as point B, but point A has a different octant value=111. Thus, there is no possibility that the drawing is stopped at point A.