This chapter’s demo allows you to see the relationship between parent and child joints, and see what happens when an individual joint is manipulated, as shown in Figure 5.9.

The demo allows you to pick from one of four joints and modify its rotation and translation values. These new values in turn affect joints that are farther down the line (child joints). By manipulating the differ­ent joints, you can see the effect of your actions on all the other joints.

The joint numbers are, from top of the screen to bottom, as follows: 1, 0, 2, 3. Joint 1 and 3 are terminal joints. They are right at the ends of the “model” and moving either of them will have no effect on the other joints in the model.

Joint 2 is the parent ofjoint 3. Changing the values of this joint causes joint 3 to move as well: try it and see. Finally, joint 0 is the root joint. Anything you do to this joint will effect every other joint on screen.