AutoCAD的一般特性（外文文献翻译）.docVIP

General Characteristics of AutoCAD Introduction to AutoCAD AutoCAD is a general purpose computer aided drafting application program designed for use on single-user, desktop personal computers and graphic workstations. It was initially developed in the early 1980s by Autodesk Inc., Sausalito, California. It is currently distributed in Australia by Autodesk Australia, now located in Sydney. These notes have been updated to describe Release 12 of that package. Concepts and definitions AutoCAD is an interactive drawing system designed to permit a user to construct or edit a drawing on a graphics display screen. To this extent, it is analogous to a wordprocessing program, except that in this case the thing being processed is a drawing. Each drawing is stored on a disk file, and AutoCAD is only able to edit one drawing (or file) at a time. This similarity to word processors is reflected in the fact that the principal functional component of AutoCAD is known as the drawing editor. Up until Release 10, AutoCAD was essentially a two-dimensional drawing system. Following that release, it now supports a full three-dimensional database. This has had the effect that the features of AutoCAD that support two-dimensional drawing are fully self-contained and can still be used as a 2D system without being concerned with its 3D features. In this course we will focus on the 2D drafting aspects of AutoCAD since that better reflects the way in which this system is generally used in practice at the present time. Several sections in these notes explain how the 3D features have been incorporated into AutoCAD, but provide little detail of the 3D operations. In order to understand AutoCAD, we must focus on a few specific concepts. Whats in an AutoCAD drawing An AutoCAD drawing is made up of entities. These can be either simple graphic primitives (such as lines, arcs, circles, text, and so on) or blocks (which are groups of entities). The graphic primitives are defined geometrically in term