8

Binding Objects (HD Solver) 443
There are two reasons to link an end effec tor to
aparent:
• You can rescale your entire hierarchy. If you
animate a robot, and t hen later decide you want
to scale the entire robot and its animation, link
the robot’s root object to a dummy, link all of
the robot’s end effectors to the same dummy,
and then scale the dummy to scale all of the
hierarchicalobjectsaswellastheanimationof
the end effectors.
• You can use linked end effectors for things like
feet or hands. End-effectors are automatically
bound to the world, so when you move a root
object in your hierarchy, the end effectors
remain behind. This is goo d for keeping feet
on the ground, but not very good for hands,
where y ou want them to move along with the
character. To have hands follow the root object,
link the end effectors of the hands to t he root
object.
Linki ng B ones to Fol low Obj ects
You can also use follow objects instead of end
effectors and bind bones to any number of follow
objects using Interactive IK.
If you use follow objects with HD IK, you do not
need to click Apply IK. The IK solver t akes care of
everything automatically.
See also
Inverse Kinematics Rollout (page 2–480)
Binding Objects (HD Solver)
Use the binding functions (page 2–474) in the HD
Solver to cause an object to attempt to maintain its
position and orientation relative to the world or to
another object. A bound object wi ll resist mot ion
in the kinematic chain until the chain is stretched
near its limits and the bound object must move to
complete the IK solution.
In the top row, the ball is independent of the lam p. In the
bottom row, the lamp head is bo und to the ball’s p osition.
Setting B inding Options
You can bind an object by position, orientation, or
both. Once an object is bound you can set binding
axes, weight, and whether the bindi ng is ab solute
or relative.
Bind Position—Causes an object to attempt to
maintain its location or to match the location of a
follow object.
Bind Orientation—Causes an object to attempt to
maintain its rotational orientation or to match the
orientation of a follow object.
Relative—Changes how an object reacts to a b ound
follow object. See the follow ing discussion about
binding an object to a follow object.
Axis and Weight—Set these options to control
which axes are affected by the binding and the
binding’s influence over other bindings in the
kinematic chain.