Advanced Models

A thorough exploration of advanced modeling falls outside the scope of this book, but several concepts and terms deserve mention if only to provide a foundation for further study. This section describes fairly complicated subjects that mostly interest programmers who want to animate models of human figures and certain types of meshes. Skip this section if you’re itching to move on to the next major topic, but there are some fun examples to explore here.

Skeletal Animation

Skeletal animation describes a technique for posing and animating models. A mesh provides the visible portion of the model like in preceding examples, but in addition, an invisible hierarchy of interconnected “joints” and “bones,” also known as an armature or rig, deforms the mesh. By animating the armature, the mesh vertices follow along. For example, a mesh representing the leg and foot of a human figure appears to lift and swing with the pivot of armature joints representing ankle, knee, and hip. The term skeletal animation suggests its primary use animating models that simulate humans or other animals, but the approach applies to almost any mesh animation, including the flag waving effect in Chapter 6.