Transitions between dynamically simulated motions: leaping, tumbling, landing, and balancing

Animating characters for video games is a challenge because a good game requires a wide variety of appealing character motion and realistic responses to unpredictable user input. Video game systems usually generate continuous action by selecting an appropriate motion from a library of data and then smoothly interpolating between the current motion and the newly selected motion. We present an alternative, simulation-based approach that computes the desired motion by making smooth transitions between a set of parameterized basis control systems. One potential advantage of dynamic simulation is that a basis control system can be parameterized to produce a variety of motions [1]. We use the term basis controller to describe a control system for a speci c low-level task such as leaping, tumbling, landing, or balancing. Each basis control system provides a set of parameters for modifying the desired behavior. For example, the basis controller for leaping allows the speci cation of the height and the distance of the jump. To produce the equivalent range of behavior using a motion library, a number of jumping sequences would have to be interpolated. By using a sequence of basis controllers, we can create a wider variety of motions for more complex tasks. Control systems can be designed so that the exit state of one control system usually leaves the simulation in a valid initial state for the next control system, making transitions easy to achieve [2]. We demonstrate the basis control systems and transitions between them by generating a diverse set of behaviors for a male and female character, including an inward 2-1/2 somersault pike, standing forward and backward somersaults, a handspring, and vari-