This report describes ANIM3D, a 3D animation library targeted at visualizing combinatorial structures. In particular, we are interested in algorithm animation. Constructing a new view for an algorithm typically takes dozens of design iterations, and can be very time-consuming. Our library eases the programmer's burden by providing high-level constructs for performing animations, and by offering an interpretive environment that eliminates the need for recompilations. This report also illustrates ANIM3D's expressiveness by developing a 3D animation of Dijkstra's shortest-path algorithm in just 70 lines of code. An accompanying videotape shows the library in use. 1 Background Algorithm animation is concerned with visualizing the internal operations of a running program in such a way that the user gains some understanding of the workings of the algorithm. Due to lack of adequate hardware, early algorithm animation systems were restricted to black-and-white animations at low frame rates ...