Modelling physical objects for simulation

The authors present a framework for modeling and simulating objects with physical attributes. Rather than attaching physical properties to geometric shapes, one directly designs and manipulates objects with intrinsic dynamic properties such as stiffness, mass, and angular momentum. Flexible and rigid bodies can interact in the same simulated physical environment, responding to collisions, fluid velocity fields, friction, and gravity. A modeler and simulator organized along these principles has been implemented and used in computer animation. The results obtained with these systems are presented