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442 Chapter 12: Animation
the object to its limit position. Use this to check
the sliding limits on an object.
Rotational Joints rollout
X, Y, Z Axis groups
Active—Activatesanaxis(X/Y/Z).Allowsthe
selected object to rotate about the activated axis.
Limited—Limits the range of rotation allowed on
an act ive axis. Use in conjunction with the From
and To spinners. Most joints are limited in their
range of rotation along an active axis. For example,
a wheel rotating around an axle could be limited to
rotat e around only one axis.
From a nd To Spinner s—Determine for rotation
limits. Use in conjunction with the Limited
function. Clicking the labels From and To rotates
the object to its limit rotation. Use this to check
therotationlimitsonanobject.
Prefer r ed Angle— Used by the H I Solver to s et the
initial pose for internal calculations. Determines
the direction of rotation preferred by a bone.
His tor y -Dependent (HD) IK
Animating with the HD IK S olver
Select a node of hierarchy or bone chain. > Animation
menu > IK Solvers > HD Solver > Click a second node of
chain.
Animating with the HD Solver lets you use sliding
joints combined with inverse kinematics. It has
controls for spring back, damping, and precedence
not found in the HI Solver. It also has quick tools
forviewingtheinitialstateoftheIKchain.Useit
for animations of machines and other assemblies.
Since this is history dependent, performance is
slower at the end of long animations. For lengthy
scenes, use HI Solvers, if possible.
Animating the End E ffectors
You animate a hierarchy of objects or bone
struc ture using HD Solvers by animating specia l
end effectors located at the bone joints. There are
two types of end effectors: Position and Rotation.
They are displayed as three intersecting blue lines
at the joint.
When you select and transform a joint that carr ies
either end effector, only the end effector itself is
transformed. The objects or bones in the chain
thenuseIKtocalculatetheIKsolution.
Animating these end effectors is much like
animating with Interac tive IK except interpolation
between keyframes uses correct IK s olutions.
Li nki ng E nd E f fectors to a Pa r ent
You can link HD IK end effectors to a parent
to achieve results similar to using bound follow
objects w ith Interactive and Applied IK. To link a
HD IK end effector, you click Link on the Motion
panel.