Further breakdown can be found here.
Renderman RIB Wrangling
This project demonstrates the basics of how a 3D scene is represented by Pixar's RenderMan scene description (rib file) protocol. In a production environment rib files are generated by applications such as Maya, Houdini and Nuke. However, writing rib files with a text editor focuses attention on the way that geometric primitives, attributes, lighting and coordinate systems are represented by Pixar's RenderMan.
Further breakdown can be found here.