8
388 Chapter 12: Animation
Start Time—
The st art time spinner is used to assig n
oredittheframevalueofatarget.Selectoneofthe
target object names i n the list window and see the
frame where the object becomes a parent. You can
adjust the value to change when the link transfer
takes place.
Key Mode group
Note: The options Key Nodes and Key Entire
Hierarchy have no effect unless the object you
areconstrainingisalreadypartofahierarchy.If
you add objects to the hierarchy after you apply
the Link constraint, you have to reapply the Lin k
constraint using the key options you desire.
No K ey—When used, no keyfr ames are wr itten
to the constrained object or its targets. T he link
control happens without inserting any keys. This
is similar to how the Link Controller worked in
3ds Max 3.1 and earlier versions.
Key Nodes—When used, keyframes are written to
thespecifiedoption.Therearetwooptions:Chil d
and Parents .Childsetsakeyframeonlyonthe
constrained object. Parents sets key frames for the
constrained object and all of its targets.
K ey Entire Hierarchy —Sets keyframes up the
hierarchy for the specified option. There are two
options: Child and Pa rents.Childsetsakeyframe
only on the constrained object and its parents.
Parents sets keyframes for the constrained object,
its targets, and their upper hierarchy.
Look At Constr ai nt
Animation menu > Constraints > LookAt Constraint
LookAt constraints enable the antenna dishes to track the
satellite.
The LookAt constraint controls an object’s
orientation so that it’s always looking at another
object. It locks an object’s rotation so that one of its
axes points toward the target object. The LookAt
axis points toward the t arget, while the Upnode
axis defines which axis points upward. If the two
coincide, a flipping behavior may result. This is
similar to pointing a target camera straig ht up.
An example of a LookAt constraint’s use would be
to constrain the eyeballs of a char acter to a point
helper. The eyes wi ll then always be aimed at the
point helper. Animate the point helper, and the
eyes follow. Even if you rotate the character’s head,
the e yes maintain their lock on the point helper.
Multiple Ta rgets and Weighting
A constrained object can be influenced by several
target objects. When using multiple targets, e ach
target has a weight value that defines the degree by
which it influences the constrained object, relative
to other targets.
UsingWeightismeaningful(andavailable)only
w ith multiple targets. A value of 0 means the
target has no influence. Any value greater than