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Pattern-Profiling Routine

IP.com Disclosure Number: IPCOM000047001D
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Reynolds, DC: AUTHOR

Abstract

Described is a program used in a graphics environment that determines whether a pattern, which is made up of straight line segments, each segment identified by the coordinates of its end points, is closed, that is, whether the pattern is a completely closed polygon. (Closed in this sense means that the pattern can be drawn with pencil and paper without lifting the pencil from the paper.) If the pattern is closed, the program sorts the points of the pattern by shape to form an array describing a closed contour. This array can then be used by a higher-level program as if it were a single simple shape. In graphics work, it is often desirable to ascertain that a figure or polygon, i.e., a pattern, is completely closed. This is useful as a preliminary step for other operations, e.g., cross hatching.

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Pattern-Profiling Routine

Described is a program used in a graphics environment that determines whether a pattern, which is made up of straight line segments, each segment identified by the coordinates of its end points, is closed, that is, whether the pattern is a completely closed polygon. (Closed in this sense means that the pattern can be drawn with pencil and paper without lifting the pencil from the paper.) If the pattern is closed, the program sorts the points of the pattern by shape to form an array describing a closed contour. This array can then be used by a higher-level program as if it were a single simple shape. In graphics work, it is often desirable to ascertain that a figure or polygon, i.e., a pattern, is completely closed. This is useful as a preliminary step for other operations, e.g., cross hatching. The pattern is formed by a collection of straight line segments, grouped as shapes and denoted by the coordinates of their end points which are stored in a linked list item representing the pattern. The pattern is profiled by sorting the coordinates of the vertices of the pattern, which is supposed to be a polygon. The order of the vertices is used to determine whether the pattern is closed. The figure illustrates the sorting technique. The coordinates are started with point 1 of shape 1 (S1P1). If this coincides with another point, the other point is stored. Successive sides of the shape are sorted in sequence. The last point of a shape should co...