The animations are now better than a Visual Basic version using an off the shelf graph control. Leigh Brookshaw has provided us with the Java Graph Class Library which does all the hard work of scaling axes etc. His original classes work best on static plots, and I kludged them to give nice animation. However his latest version 2.4 comes with an example of how to add double buffering externally, which I haven't yet tried. A separate difficulty is the documentation to go with the demonstrations.
More complicated structures are essentially impossible.
I have experimented with IBM's TechExplorer and am quite encouraged by this possibility, but it is unfortunately only available for Windows as yet. HTML 3.0 seemed to promise much for typesetting technical text, but HTML 3.2, which is likely to be implemented, dropped these enhancements. I am optimistic that in a year from now, when I may actually teach the class again, Java will provide a useful platform independent tool for computer aided teaching. Producing good accompanying text is a second challenge.