How to customize an AIS_InteractiveObject?

Hi,
I've learned some knowledge about OCC for some time. Now I can create shapes like cylinders and change their colors, but when I'm reading the source code of AIS_ViewCube I feel confused. I dont understand the usage of fields and methods in the code .I want to learn the process of creating custom shapes.First step, I want to understand the source code of AIS_ViewCube. Do you have any recommended learning materials?
Thanks a lot!