A Fast Line Clipping Algorithm for Circular Windows

It is hard to speed up the line clipping for circular windows due to the complex calculation adopted in the current algorithms. Making use of the linear relation between a circle and its tangent square, this paper prepares a normalized intersection table and realizes a new line-clipping algorithm via mapping and table checking. The algorithm has much higher speed than the current ones due to avoidance of calculations of line-circle intersection, point-line distance, and point-point distance.