9
480 Chapter 12: Animation
Twist End group
Enabled—Turns on the display of the end twist
manipulator. Default=on.
Size—Sets the size of the end twist manipulator.
Default=1.0.
Lengt h—Sets the length of the end twist
manipulator. Default=75.0.
Goal Display group
Enabled—Turns on the display of the IK goal.
Default=on.
Size—Sets the size of the IK goal. Default=30.0.
IK Solver Display group
Enabled—Turns on the displa y of the IK chain
object. Default=off.
See also
Animating with the Spline IK Solver (page 2–473)
Interactive and Applied IK
Animating with Inter active IK
Select the end of a hierarchy > Hierarchy panel > IK >
Interactive IK.
With Interactive IK and the Auto Key button
turned on, you position your model on keyframes,
and the IK solution is interpolated between those
keyf rames. Because the IK s olution accounts for
multiple objects and the joints between objects, the
interpolated animation of an IK object is usually
different f rom the animation of objects without IK.
Tip: InteractiveIKisafeaturecarriedoverfromthe
earliest version of the software. It is recommended
that you explore the IK Solver methods first, and
only use Interactive IK if you find the IK Solvers
will not satisfy your needs.
ExampleofInteractiveIK
Thefollowingexampledemonstrateshowan
int eractive IK animation works and how it might
differ from what you expect. The figure shows an
IK str ucture with its end effector resting on top of
a box. The box moves in a straight line over 100
frames.
Turn the Auto Key button on and then i n the
Hierarchy panel > IK tab, turn on Interact ive IK.
Mov e the end effector of the IK structure to rest
on top of the box at frame 100. The interpolated
animation of the end effector follows a natural
looking curved path.
You might have expected the IK bone struc ture
to follow the same path as the box. However, the
IK solution is only calculated at the keyf r ames.
The positions and rotations of all the objects in
the kinematic chain are interpolated between the
keyframes to produce the curved result.
To make the end effector closely follow the path of
the box, you would have to add more keyframes.
You can a lso use binding and standard applied
IK. For information about maki ng the end
effector precisely follow the motion of the box, see
Animating with Applied IK (page 2–481).