Animating a ball bouncing or car stopping is one thing, but what if you want to create animation with a natural looking structure for movement - like a skeleton? Flash CS4 introduced Inverse Kinematics which allows for lifelike movement of objects. You can literally create a bone structure that spans between instances on the stage. This allows for different poses that are animated much like tweens are animated.
In order to use the Bone Tool in this way, your objects must be symbols. (In a later section you will see how to use the Bone Tool on Shapes.)
Open our example, saved as AdvancedAnimation/demos/IK-demo-done.fla. Use the selection tool to drag the pieces and watch how they move.
If you would like to try, open AdvancedAnimation/demos/IK-demo.fla. Using the Bone Tool (), click and drag from the first piece to the second. Then, click again from the second to the third. The point you click will be the joint.
Above, you can see the first bone in place. Below, you can see how they move together when dragged.