Many of the examples in this directory are direct ports of the demos put 
together by Humus. I've ended up having to modify them somewhat as he does
some "interesting" things in his rendering library - such as inverting the 
Y axis calculations. However, you can find the original C++ demos at the 
following page:

http://esprit.campus.luth.se/~humus/3D/index.php?page=OpenGL

You can tell stuff derived from his demos due to the Humus-* prefix to them.
He hasn't attached any copyright notices or such to any of the code, so 
I assume it's pretty safe to use everything.