Virtual reality interfaces for feature-based computer-aided design systems

A computer-aided design (CAD) system with a virtual reality (VR) interface simplifies the design of complex mechanical parts. To add a design feature (e.g., a hole,slot, or protrusion), the designer can navigate in the part to the appropriate face of the part where he/she wishes to attach the feature, and sketch directly on that face.Besides convenience, this method of feature specification implicitly enforces feature accessibility constraints, and also provides hints to the process-planner regarding the order in which the features may be manufactured. We detail the design of a VR-based prototype CAD system. The system maintains the knowledge of part cavities and their adjacencies, and a triangulated boundary-representation of an approximating polyhedron. We present incremental provably correct algorithms for updatingthis representation as the user edits the part. We also show how this representation supports real-time displays, navigation, and collision detection. The user-interface of the CAD system relies on these capabilities to provide the above-mentioned advantages