The custom handlers presented in this chapter can be expanded in several key directions. First, the error checking can be expanded depending on your needs. Error checking can become quite complex and can consist of both User mode error checking and Authoring mode error checking. Another consideration would be to develop a debugging mode used to turn on and off surfaces.
More importantly, though, perhaps the most robust change that we will explore is the move from simple custom handlers to dedicated parent/child scripts. This is explored in depth in Chapter 23, "Controling Time." Parent/child scripts are well suited to the objects we are creating in the 3D world. Remember, parent/child scripts are very similar to behaviors. The key difference is that parent/child scripts are not attached to the score in any way. Similarly, the Models, Shaders, Cameras, and other Nodes we are working with do not have a representation on the score.
Beyond this visual similarity, parent/child scripts allow us to connect our Models to robust systems of control. The systems that we will look at include creation and destruction methods, scheduling, and hooks for collision, physics, and basic AI. Because Nodes in the 3D world are not score based, advanced applications may avoid utilizing the score for most control issues. A dedicated scheduler can be used to take the place of most Playback Head functionality.