http://www.cc.gatech.edu/gvu/softviz/parviz/polka.html

POLKA was created by the Software Visualization group at Georgia Tech beginning in 1993. Its focus is on animating algorithms and other time-dependent concepts. It runs under XWindows and, more recently, Microsoft Windows. Some algorithms which have been implemented in POLKA include quicksort, finding a minimum spanning tree, and an unspecified parallel sort. POLKA (and its front-end, SAMBA) are C++ programs. The POLKA/Windows distribution does not include compiled versions of the visualizations, so users will need to compile them from old Microsoft Studio project files.

From the developer's site:

• POLKA is a general purpose animation system that is particularly well-suited to building algorithm and program animations. One of the first foci for the system was to build animations of parallel programs and computations, but POLKA is ideal for animating good old serial programs too. POLKA is descended from the XTango system, but it is far more powerful and flexible. All of our most recent development was with POLKA, not XTango. POLKA supports color, real-time, 2 & 1/2 dimensional, smooth animations. ... The focus of the system is on a balance of power and ease-of-use. POLKA provides its own high-level abstractions to make the creation of animations easier and faster than with many other systems. Programmers need not be graphics experts to develop their own animations.