We present an interactive modeling and animation system that facilitates the integration of a variety of simulation and animation paradigms. This system permits the modeling of diverse objects that change in shape, appearance, and behavior. Because all properties are functions of time, and because we integrate modeling and animation, we refer to our system as a ``4D modeler.'' Changes in properties can be effected by various methods of control, including scripted, gestural, and behavioral specification. The system is an extensible testbed that supports research in the interaction of disparate control methods. The paper discusses some of the issues in modeling such interactions and mechanisms implemented to provide solutions. An object-oriented architecture uses delegation hierarchies to exploit multiple inheritance and to permit objects to change all of their attributes dynamically, including object type. Objects include displayable objects, controllers, cameras, lights, renderers, and user interfaces. Further, the delegation system permits network distribution of objects and their associated computation. Additional ways to obtain real-time update speeds include the use of data dependency networks, extensive caching to exploit inter- and intra-frame coherency, and lazy evaluation.

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Last Modified: Mon Sep 11 15:10:16 2000