Autodesk 12812-051462-9011 User Guide 3 - Page 2708

End Effector In history-dependent inverse kinematics (HD IK) on page 3422, the end effector is the pivot point of the selected child object at the end of a kinematic chain. The kinematic chain is a single branch of a hierarchy used for animation with inverse kinematics (IK) on page 8016. The chain starts with the selected child object and travels up through ancestors until it reaches the start of the chain. When you move the end effector, the HD IK solver then uses IK calculations to move and rotate all other objects in the kinematic chain to react to the object you moved. The end effector has two transforms: one that connects it to its parent, and another that connects it to the End Effector Parent. By default, the End Effector Parent is none (equivalent to World); you can assign this in the Motion panel. NOTE You can move the end effector away from the child object, which causes the IK chain to straighten out. When you move the end effector back toward the child object, joints in the IK chain will bend again. See also: ■ IK Goal on page 8008 Envelopes In Physique on page 4603, the envelope is the primary tool for controlling skin deformation. An envelope defines an area of influence about a single link in the hierarchy. If the envelope is deformable on page 7948, mesh vertices within that envelope follow the movement of the Physique deformation spline on page 7949. An envelope has a pair of inner and outer bounds; the envelope's influence is strongest at the inner bound, and falls off toward the outer bound. By default, each envelope has four cross sections. You can reshape the cross sections, or add new ones, to change the envelope's geometry. In the Skin modifier on page 1672, the envelope plays a similar role with respect to bones. Each bone has its own envelope with two or more cross-sections that allow you to shape the envelope to fit the surrounding mesh. Typically, the envelopes of adjacent links or bones overlap each other. Vertices that fall in the overlap area are weighted to produce smooth blending at joint intersections. Glossary | 7963