A SWEEP-LINE ALGORITHM AND ITS APPLICATION
TO SPIRAL POCKETING

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This paper presents an efficient line-offset algorithm for general polygonal shapes with islands. A developed sweep-line algorithm (SL) is introduced to find all self-intersection points accurately and quickly. The previous work is limited to handle polygons that having no line-segments in parallel to sweep-line directions. The developed sweep-line algorithm (SL) saving the calculation time and using a new method to find polygon self-intersection points. An invalid loop detection and removing (ILDR) algorithm is developed. The invalid loops detection algorithm divides the polygon at self-intersection points into a set of small polygons, and re-polygonized them. The polygons are checked for direction; invalid polygons are always having inverse direction with the boundary polygon. The proposed algorithm has been implemented in Visual C++ and applied to offset point sequence curves, which contain several islands



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© Copyright 2002 Professor F.R. Hall - University of Wolverhampton.