It's unrealistic to expect anyone to read a lengthy programmer's guide from start to finish. After you read a few basic chapters, you can skim others and skip around, depending on your particular needs and goals. Here are a few suggested paths for making your way through this book.
For a basic understanding of how to create nodes and connect them into scene graphs, read Chapters Chapter 1, Overview through Chapter 5, Shapes, Properties, and Binding. Then read chapter Chapter 8, Applying Actions, “Applying Actions,” and chapter Chapter 10, Handling Events and Selection, “Handling Events and Selection.”
If you are mainly interested in reading files into the Inventor database, read Chapters Chapter 1, Overview and Chapter 2, An Open Inventor Sampler for an overview of Inventor, and then jump to chapter Chapter 12, Importing data, “Importing Data.”
If you are an experienced OpenGL programmer, Chapters Chapter 1, Overview, Chapter 2, An Open Inventor Sampler, Chapter 10, Handling Events and Selection, and Chapter 28, Using Open Inventor with OpenGL, “Using Inventor with OpenGL,” are important chapters to begin with. Again, for a basic understanding of building a scene graph, you also need to read Chapters Chapter 3, Nodes and Groups through Chapter 5, Shapes, Properties, and Binding and Chapter Chapter 8, Applying Actions.
Chapter 17, Draggers and Manipulators, “Draggers and Manipulators,” and Chapter 18, Open Inventor Component Library, “Inventor Component Library,” describe the programming aspects of Inventor that have an associated user interface. The user interface for individual components is described in the on-line HELP cards provided for each class.
Once you understand the basic material presented in Chapters 1 through 5, you can skip to Chapter 15, Engines, “Engines,” and Chapter 16, Node Kits, “Node Kits.” Engines, like nodes, are basic building blocks in the scene graph. They allow you to animate parts of the scene graph and to incorporate additional behavior into scene graph objects. If you are creating scene graphs, node kits offer many shortcuts.