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466 Chapter 12: Animation
Common Joint Types
The most common joint types are Rotational and
Sliding joints. Other common joint types are Path
and Surface joints. Each joint t ype displays its own
set of joint parameters.
Rotational joints—Control rotation of objects
using many of the standard rotat ion controllers.
The p ar ameters for rotational joints set an object’s
ability to rotate about a given axis.
FormanyIKstructures,considerusing
an
Euler XYZ controller (page 2–312) .
Quaternion-based controllers tend to freeze if an
objectismovedbeyondrotationaljointlimits
before turning on IK.
Sliding joints—Control the position of objects
using many of the standard position cont rollers.
The parameters for sliding joints control whether
anobjectcanmovealongagivenaxis.
Surf ace joints—Control the position of objects
using
Surface constraint (page 2–379) .The
parameters control how the object travels along
its assigned surface.
Path joints—Control the positional motion of
objects using
Path constraint (page 2–380) .The
parameters for path joints control how far an
object can tr avel a long its assigned path.
Usin g J oint Pa ra meter s
Thewaythechildrenbehavetowardoneanother
is governed by the inheritance of the tr ansforms
down the chain. Setting
joint limits on individual
child objects can influence this inheritance. If
three children in a row all have their rotational
axes made inactive, they will not be able to rotate,
and so a piece of the chain will appear stiff. Or if
only one axis is made active as a sliding joint, the
component can separate in space from the chain.
When you are using an object with a path
constraint in an IK chain you might want the path
to appear as if it is part of the IK chain. You achieve
this effec t by linking the object using the path
constraint and the path to the same p arent. The
path object should have no children, and other
objects in the IK chain should be linked to the
object using the path constraint.
1. Base
2. Post
3. Cap
4. Ring
5. Holder
6. Handle