2009

■ The root object is at or near the hierarchy’s virtual center of mass.
The object that best satisfies these criteria is your root object. You then create
your hierarchy with all of the other objects as descendants of that root object.
Linking Objects for Inverse Kinematics
Inverse kinematics (IK) uses the child object as the driving force for the
animation. IK is less forgiving and is highly dependent on the linking strategy
for performing calculations.
You need to consider two additional principles when linking hierarchies for
use with inverse kinematics:
■ Links and pivot placement simulate real-world joint locations.
■ Choose an object near the structure’s center of mass, or center of gravity,
as the root of the hierarchy. The center of mass in the real world is the
point on an object about which reactions to external forces are applied.
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