A line clipping algorithm and its analysis

One of the classical problems of Computer Graphics: line clipping against a rectangle is revisited. Coordinate raster refinement and some unusual forms of the parametric equation of the line are used to develop formulae for a line clipping algorithm. The algorithm is first presented in a form, where clarity of presentation is the prime concern. It is then transformed into one big nested branch, which after optimisation is assumed to be the most efficient form with a heavy cost on size. It is assumed that any mathematical consideration of the clipping problem would after a similar optimisation lead to a branching structure of equal complexity and speed. Line clipping thus belongs to the class of problems for which after a proper mathematical and logical analysis automatic program transformations may do the rest. This work has been supported by a grant from the Hungarian Academy of Sciences, Project No. OTKA 2572/1991