This chapter will finally explore some serious 3D rendering, multi-pass rendering, and procedural modeling. We'll go through several more large-scale examples of rendering 3D scenes and take a look at numerous techniques for modeling. In order to achieve this, we will talk a lot about SOPs. SOPs can seem to be complicated, but do not forget that what we are actually doing when we go about 3D rendering is interfacing OpenGL in a fancy, convenient way. So if you feel confused or overwhelmed by the principles or vocabulary, don't hesitate to look up beginner's literature on OpenGL, be it to get a deeper understanding of Non-uniform Rational B-Splines (NURBS), primitives, lights, or anything else in this context. The most common reference for OpenGL is the Official Guide to Learning OpenGL, often called the Red Book, which is available at http://www.glprogramming.com/red/.