Animate the rotating cube using active rendering.

The source code is from:

Pro Java 6 3D Game Development
Andrew Davison
Apress, April 2007
ISBN: 1590598172
http://www.apress.com/book/bookDisplay.html?bID=10256
Web Site for the book: http://fivedots.coe.psu.ac.th/~ad/jg2

Contact Address:
Dr. Andrew Davison
Dept. of Computer Engineering
Prince of Songkla University
Hat Yai, Songkhla 90112, Thailand
E-mail: ad@fivedots.coe.psu.ac.th

If you use this code, please mention my name, and include a link to the book's Web site.
Thanks,
  Andrew

@since Ptolemy II 8.1