A Sweep-Line Algorithm and Its Application to Spiral Pocketing.(Dept.M)

Abstract

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 sell-intersection points accurately and quickly. The previous work is limited to handle polygons that having no line-segments in parallel to $Weep-line directions. An invalid loop detection and removing (ILDR) algorithm is proposed. The invalid loops detection algorithm divides the polygon al 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 scquence curves, which contain several islands.