Computer-Aided Structural Engineering (CASE) Project. User's Guide: Computer Graphics Program for Generation of Engineering Geometry (SKETCH).

摘要

SKETCH is a FORTRAN program which is intended to provide quick and painless generation of engineering geometry. The program will utilize any of a number of Tektronix storage tube terminals, including the 4010 and the 4014. Input devices include the terminal keyboard, cross hair thumbwheels, Tek 4953 and 4963 digitizing tablets, and an experimental mouse developed at LSU. The objective of the program is to automatically convert two-dimensional 'picture' data into a rich data base consisting of three-dimensional coordinates, lines, polygonal faces, curves, and surfaces. The version of SKETCH (Version 3, Modification 1) that this document reflects does not, as yet, support surface patches (faces with curved boundaries). In order to create complex geometry involving curve segments (and in the future surface patch data), a polyhedra description is roughly sketched, dimensioned, and automatically converted to three-dimensional data. The lines of the precisely dimensioned polyhedra and polygonal cross sections serve as control data and boundary conditions to define arcs, circles, and quadratic or cubic curve forms. (Author)