An alternative approach to simulation is "key framing". This is the animation approach used in traditional cel animation. The animator starts by specifying the positions and orientations at various key points in time. In-betweeners generate the images in-between the key frames. This was once a job for apprentice animators. These days it is largely done by computer.

The images in this section are taken from a classical paper on animation by John Lasseter from Pixar. "Principles of Traditional Animation Applied to 3D Computer Graphics," SIGGRAPH'87, pp. 35-44.