An Extension Of Weiler-Atherton Algorithm To Cope With The   Self-intersecting Polygon
  In this paper a new algorithm has been proposed which can fix the problem of Weiler Atherton algorithm. The problem of Weiler Atherton algorithm lies in clipping self intersecting polygon. Clipping self intersecting polygon is not considered in Weiler Atherton algorithm and hence it is also a main disadvantage of this algorithm. In our new algorithm a self intersecting polygon has been divided into non self intersecting contours and then perform the Weiler Atherton clipping algorithm on those sub polygons. For holes we have to store the edges that is not own boundary of hole contour from recently clipped polygon. Thus if both contour is hole then we have to store all the edges of the recently clipped polygon. Finally the resultant polygon has been produced by eliminating all the stored edges. 
Anurag Chakraborty
cs.GR cs.CG