Apple Motion 4 - Manual (Page 467)

The values of the source parameter can be scaled to more accurately apply to the
destination parameter, so for example a source parameter with a range of 1–100 can be
scaled when applied to a parameter with a range of 0 – 1. The values can also be offset
from the source, and the effect can be mixed with the destination value in a variety of
ways to create different resulting effects.
The Link behavior can be applied to parameters that have been animated with behaviors
or keyframes; however, it does not affect the parameter when the Start Values or End
Values are zero.
When using the Link behavior to control an object’s position parameter, the linked
coordinates are based on the center point of the current group. So when an object is
linked to another object within the same group, it will share an identical position. However,
if the source object is in a different group, the coordinates may appear offset in space.
If your goal is to match an identical position across groups with different center points,
you can create an invisible dummy object in the group containing the source, link it to
the source object, then use the Match Move behavior to copy the dummy object’s position
to that of the intended target. Match Move automatically compensates for inter-group
position offsets and provides the option to either attach one object to another or to
mimic the source object’s transformations. For more about Match Move, see
Motion
Tracking Behaviors .
You can also link to the group’s coordinates instead of the object’s, and use the Offset
parameters in the Link behavior to obtain the position you want. However, if that group
is subsequently added to another group, the linked object may again not move as
expected.
Parameters in the Inspector
Source Object: The object in which the source parameter resides. Click the To pop-up
menu to select from the objects in the current project.
Source Parameter: The Source Parameter (Compatible Parameters) pop-up menu shows
the parameter that serves as the source for the Link behavior and can be used to select
a new source parameter. Only parameters with the same value type and number of
attributes as the parameter selected in the Apply To (Target Parameters) pop-up menu
appear here.
Note: When possible, this parameter will default to the identical parameter in the source
object as has been selected in the Apply To parameter.
Important: Changing the Apply To (Target Parameters) setting will change which
parameters appear in the Source Parameter (Compatible Parameters) pop-up menu. If
you cannot find the parameter you are looking for, you may need to first choose a Target
Parameter to which you can link.
467 Chapter 9 Using Behaviors