Abstract: A method and apparatus for user interaction with animated objects displayed in a repeatedly updated 3-D computer simulated environment using 2-D cursor and button input. The invention provides for user manipulation of 3-D objects in a simulation where conflicting goals may be simultaneously applied to the objects and resolved. All goals acting on an object are translated to equivalent information in terms of physical forces, and are applied as forces via a physically based model, where this model has no knowledge as to the source of each force. Each user is treated as an entity in the environment, with a positional presence. The positional presence of a user is represented by a user object displayed in the simulation. The invention provides a unique interface to a real-time simulation that is easy to use, by virtue of mapping a subset of the inputs to actions consistent with the expectation of the user actually being physically present within the environment.