A method and apparatus wherein complex physical interactions and collisions are modeled at a high level of detail while reducing the computational demands placed on the processing system. In one embodiment the method comprising the steps of defining a first object and a second object, each object adapted for colliding with the other object; assigning an interaction type for at least one of the first and second object in response to an object parameter; and selecting between a continuous simulation of a collision and a discrete simulation of the collision in response to the interaction type.