Creating motions of objects or characters that are physically plausible and follow an animator's intent is a key task in computer animation. The spacetime constraints paradigm is a valuable approach to this problem. It computes optimal physical trajectories that are solutions of a variational spacetime problem. Such techniques calculate acting forces that minimize an objective functional while guaranteeing that the resulting motion satisfies prescribed spacetime constraints, e.g., interpolates a set of keyframes. Resulting forces are optimally distributed over the whole animation and show effects like squash-and-stretch, timing, or anticipation that are desired in animation.
In this talk, we give an introduction to spacetime constraints and - if time permits - sketch a recent approach to interactive spacetime optimization for deformable objects.