QUISP : A computer processor for the design and display of quadric-surface bodies

Abstract

QUISP outputs line drawings of the quadric-surface bodies, with optional removal of hidden curves. All the lines in the drawings are projections of Quadric-Surface Intersection Curves (QSICs), which are calculated using parametric methods.

Because these quadric-surface bodies are so useful for modelling man-made objects, it is important that any Computer-Aided Design (CAD) system be able to work with such bodies. The "QUISP" processor described here was designed to accept descriptions of quadric-surface bodies in either character-string form (via the "QUADRIL" language), or through interactive input.

QUADRIL has a mixture of English-like and algebraic syntax. It may be used to specify quadric-surface bodies and then to display them on a variety of media. The interactive input allows commands to be entered by push-buttons to accomplish anything that QUADRIL can do.

Most man-made objects can be closely approximated by bodies whose surfaces are composed of portions of second-order (quadric) surfaces. These surfaces include elliptic, hyperbolic, and parabolic cylinders, as well as quadric cones, paraboloids, hyperboloids, ellipsoids, and pairs of planes. Simple planes (first-order surfaces) may be included as degenerate quadric surfaces.