Constraint-based 3D Direct Manipulations for Intuitive and Precise Solid Modelling in a Virtual Reality Environment

Abstract

The absence of constraints when interacting with virtual objects is one of the major limitations in the current Virtual Reality (VR) environments. Without constraints, it is difficult to perform precise interactive manipulations and precise solid modelling in VR environments cannot be ensured. In this paper, constraint-based 3D direct manipulations are acquired through incorporating constraints into the VR environment for intuitive and precise solid modelling. Solid modelling in the VR environment is precisely performed in an intuitive manner through precise constraint-based manipulations. Constraint-based manipulations are accompanied by automatic constraint recognition and precise constraint satisfaction and are realized by allowable motions for precise 3D interactions in the VR environment. The allowable motions are represented as a mathematical matrix for conveniently deriving the allowable motions from constraints. A procedure-based degree-of-freedom incorporation approach for 3D constraint solving is presented to derive the allowable motions. A rule-based constraint recognition engine is developed for both constraint-based manipulations and implicitly incorporating constraints into the VR environment. Some special constraint-based manipulations are also implemented as modelling operations for solid modelling in the VR environment.