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Inverse Kinematics (IK)
Using IK to animate a leg
Inverse kinematics (
IK on page 8016) is a method of animating that reverses the
direction of the chain manipulation. Rather than work from the root of the
tree, it works from the leaves.
Let's take the example of an arm. To animate an arm using forward kinematics,
you rotate the upper arm away from the shoulder, then rotate the forearm,
the hand from the wrist and so, on adding rotation keys for each child object.
To animate the arm using inverse kinematics, you move a goal that positions
the wrist. The upper and lower arms are rotated by the IK solution which
3374 | Chapter 15 Animation