This is the first part of a tutorial series that will take your knowledge about After Effects expressions to the next level. We start with the very basics and then get step by step to more advanced topics.
This iExpression allows to animate an entire arm by just specifying the point where the hand should be - the expression calculates the rotation of all arm segments accordingly (using Inverse Kinematics, IK). You tell where the arm should move - the expression knows how.
With this iExpression you can connect a property to another one in an elastic way. This is like a linking expression,
but the property follows the linked property not directly, but in a delayed, elastic way.