2009

Joint Controls
Setting Joint Parameters
You set whether a joint behaves as a hinge, a drawer slide, or another type of
joint by setting
joint parameters on page 3418 for each object in the kinematic
chain. Joints control the rotation and position of an object with respect to its
parent.
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 hierarchy of object or bone systems can have its joint limits defined.
Select all the objects, and turn on their bone or link 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 using a bone system,
add the IK solvers first, then set the joint limits second.
Common Joint 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 Control 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.
For many IK structures, consider using an
Euler XYZ controller on page 3151.
Quaternion-based controllers tend to freeze if an object is moved beyond
rotational joint limits before turning on IK.
Sliding joints Control the position of objects using many of the standard
position controllers. The parameters for sliding joints control whether an
object can move along a given axis.
3466 | Chapter 15 Animation