Development Of 3D Modeling System In Engineering Graphics Based On Virtual Environment

"Engineering Graphicsis"a basic course in engineering disciplines and plays an important role in the whole education system. Using the CAI software made by virtual reality methods can enhance the ability in the space imagination of students, at the same time, such software can also enable students independent learning to increase their learning efficiency.This paper discusses the current reseach and the problems on "Engineering Graphics"CAI coursewares.And it describes the background, the purpose and the meaning of this subject.Based on the problems,the specific solutions are raised in this paper.It alse introduces the system development tools. And it analyses the application environment and the characteristics of the kernel in geometric modeling.This paper introduces the modeling process using UML.The window structure of this system adopts the MFC technology.And the relevant elements of MFC framework are describes in this paper.The main elements of the interface are designed in this system,including the menu bar, graphical toolbars,display areas and modeling control areas.According to the geometric modeling kernel of Open CASCADE,a OCAF-based single-document application framework is established. On this basis,the prototype of the entity class model and the interface class model is implementated. Open CASCADE provides the basic geometry modeling,such as cylinder,sphere,which is generated by special functions. Using the Boolean modeling methods provided by Open CASCADE kernel,the complex 3D models can be generated interactivly in a virtual environment. Using example,this paper introduces the application in teaching of this system. Using this system in teaching can inspire the students' innovative thinking and inprove the ability of spatial thinking.In this system,the students may model the struture according to their own ideas and change the size and the position of various parts flexiblly. Students can improve their spatial thinking ability through changing strutures and and comparative analysis of 2D engineering drawings.