Virtual physics for virtual reality

We consider the problem of giving virtual reality objects physical behaviour We wish to do this in a way which allows users to construct new objects from simpler ones and have the correct composite behaviour emerge. Our approach uses a graph structure to model, dynamically, the way one object can influence another It uses a lightweight message system to cause actions between objects. It has routines to encode each kind of general physical behaviour Any given object can have multiple independent behaviours and these behaviours can be extended to give a richer range of outcomes. These outcomes arise from the creative use to which the objects are put by the user rather than from predetermined actions built-in when the VE was designed. In addition, we replace hierarchical geometry modelling with a much flatter structure. We explain the approach, describe the implementation, suggest enhancements and a range of tests which demonstrate the concepts in action.