Clipping and Covering

Abstract

We now have the ability to create graphical objects of arbitrary sizes and complexities in the observer coordinate system. Unfortunately the available graphical devices are of fixed sizes (usually rectangular). Thus, parts of an object that lie outside this boundary rectangle may cause problems. In most devices these external line segments are ignored; however, on some devices (in particular, microfilm plotters) these lines are reflected back into view causing (artistic!) confusion. This effect may be deliberately used to produce some unusual designs; figure 4.1 is such a diagram, which was drawn by one of my students.