Packages Provides an easy to use scene graph API that is intended for use by OpenGL Programmers, without preventing access to low-level OpenGL features.

If you're interested in constructing arbitrary OpenGL objects, take a look at the Visible interface.

Model designers might be more interested in the model subpackage. This package contains the core components of the Vertex Modeler application.

Model designers will be most interested in the Model and VertexUtil classes; examine their documentation closely, since you'll be using them extensively.  Being aware of the other classes in this package would be handy, as well.