Functional Implementations of Continuous Modeled Animation (Expanded Version)

Animation is a temporally continuous phenomenon, but is typically programmed in terms of a discrete sequence of changes. The use of discreteness serves to accommodate the machine that is presenting an animation, rather than the person modeling an animation with the help of a computer. Using a continuous model of time for animation allows for natural specification, avoiding some artificial details, but is difficult to implement with generality, robustness and efficiency. This paper presents and motivates continuous modeled animation , and sketches out a naïve functional implementation for it. An examination of some of the practical problems with this implementation leads to several alternate representations, all of which have difficulties in themselves, some quite subtle. We hope that the insights and techniques discussed in this paper lead to still better representations, so that animation may be specified in natural terms without significant loss of performance. A shorter version of this report appeared in the proceedings of PLILP/ALP ’98, and is © Springer-Verlag .