9

Setting Joint Parameters 483
effectors but do not want keys generated on ever y
frame.
TurnonApplyOnlyToKeystoconstraintheIK
solution to fr ames with end effector keys.
Watching Progr ess of the I K Sol ution
N ormally, Apply IK calculates all frames before
updating the viewpor ts. To watch the progress
of Apply IK frame by frame, turn on Update
Viewports on the Inverse Kinematics rollout.
Updating the v iewports g reatly slows down the
ApplyIKprocessbutitcanhelpyoutroubleshoot
complex animations.
Joi nt Cont r ols
S etting J oint Par ameters
You set whether a joint behaves as a hinge, a
dra wer slide, or another type of joint by setting
joint parameters (page 2–459) for each object in the
kinema tic chain. Joints control the rotation and
position of an object with respect to its paren t.
Any object has a maximum of two joint-type
rollouts: One rollout contains settings to control
the object’s position, and the other controls the
object’s rotation. There can be many different
types of positional and rotational joints. Which
joint parameters are available is determined by the
type of IK solver assigned to an object. HI Solvers,
for instance, are controlled with a preferred angle
setting found in the Rotational Joint parameters.
HD Solvers have additional parameters for spring
back, precedence, and damping, not found in the
HI Solver.
Any hierarch y of object or bone systems can have
its joint limits defined. Select all the objects, and
turn on their bone or l ink display. Select the
bone or link and open the Hierarchy panel > IK
tab. Scroll down to the Sliding and Rotational
Joints. There, you can activate axes and set their
individual limits.
Note: Different IK solvers use different joint limits.
When us ing a bone system, add the IK solvers first,
thensetthejointlimitssecond.
Common J oint Types
The most common joint types are Rotational and
Sliding joints. Other common joint types are Path
and Surface joints. Each joint type displays its own
set of joint parameters.
Rotational joints—Cont rol rotation of objects
using many of the standard rotation controllers.
The parameters for rotational joints set an object’s
ability to rotate about a given axis.
FormanyIKstructures,considerusing
an Euler XYZ controller (page 2–318).
Quaternion-based cont rollers tend to freeze if an
objectismovedbeyondrotationaljointlimits
before turning on IK.
Sliding j oints—Control the position of objects
using many of the standard position controllers.
The parameters for sliding join ts control whether
anobjectcanmovealongagivenaxis.
Surf ace joints—Control the position of objects
using Surface constraint (page 2–396).The
parameters control how the object travels along
its assig ned surface.
Path joints—Control the positional motion of
objects using Path constraint (page 2–398).The
parameters for path joints control how far an
object can travel along its assig ned path.
Usin g J oint Par ameter s
The way the children behave toward one another
is gover ned by the inheritance of the transforms