9
Choosing Child-to-Parent Precedence (HD Solver) 469
effector and progresses up the IK chain until the
base object is reached.
Using methods described in t he following topics
you can change the default precedence va lues.
You can also set your k inematic chain back to its
default precedence.
Toresetthedefaultjointprecedence:
1.
Select all objects in the kinematic chain.
2. On the Hierarchy panel, expand the Object
Parameters rollout.
3. Set Precedence to 0.
Note: Default joint precedence o ccurs w henever
all joints in the k inem atic chain have the same
precedence value. Assigning a value of 100 to
all objects in the kinematic chain is exactly the
same as assigning a value of 0.
Choosi n g Ch i ld -t o -Par e nt
Pr ecedence (H D S olv er )
Child–>Parent precedence causes joints closest to
where a force is applied (the end effector) to move
more than joints that are farther away from the
force. Like the default precedence, Child->Parent
precedence produces a natural result that is
suitable for many IK solutions.
ThedifferenceisthatChild
>Parent precedence
assigns unique v alues to each object in the
kinematic chain (default precedence uses the
value of 0 for every object). Chi ld
>Parent
precedence is more flexible if you want to go back
and manually change precedence values.
The first figure shows values for child-to-parent precedence.
Ass igni ng Chil d->Pa rent Pr ecedence
Clicking Child >Parent sets joint precedence
basedonachildhavingahigherprecedencethan
its parent. The values are calculated by setting the
root of the entire hierarchy to a precedence value
of 0 and each child to a value equal to 10 times its
depth from the root.
You almost always assign Child->Parent
precedence to an entire kinematic chain. The
chainforthestructureinthefigureusesthebody
as the root object and the duck as the end effector.
Each object receives a value equal to its depth
from the root of the hierarchy times 10. Note that
precedence value calculation is based on the root
of the hierarchy whether or not the root is selec ted
as part of the kinematic chain.