VB-based System Design And Implementation Of Secondary Development Of AutoCAD

The AutoCAD, as a generally software for computer-aided design, due to its powerful design functions, has been widely used in mechanicals, electronics, electrics, architecture, clothing, and other fields. It's one of the world's most widely used tools for computer-aided design. However, in practical applications, there are still many disadvantages in AutoCAD, such as poorly computing capabilities, difficultly drawing some special curves and complex surfaces. Therefore, the design of a AutoCAD based developlement system is an effective way to overcome the shortcomings of AutoCAD.The development process of CAD is presented in this thesis. The outlining of the AutoCAD software in the engineering field and teaching as well as profiles of its significance for AutoCAD based development platform is also addressed. A survey of the AutoCAD development languages is proposed. After comparing various languages for secondary development, the Visual BASIC (VB) program language is selected to develop the AutoCAD software, because of its highlight advantages.The requirements of the AutoCAD based software system which is based on the VB are analyzed, including the user interface, the securities and reliability, the functions of the system, and the software's environment. This paper also gives a detailed description for designing the software interface and calling the AutoCAD software by VB language. The basic drawing commands in the VB to call the AutoCAD API is discussed and anaylized. The steps of automatical generating two-dimensional engineering graphics from 3D model in the AutoCAD are also discussed. Several designing examples of 3D model, including springs, rotating stairs, and worms, in which the designing ideas, processes and procedures are made, show that the system developed is effective and applicable.The system test is also addressed. The primary testing results show that our system meets the requirements and is reliable.