As well as linking a parameter to multiple parameters, you can link a parameter to the orientation of an object. When you link to an object's orientation, you link to the "complete" orientation of an object that is calculated in quaternion space; that is, you don't link to the object's individual Euler X, Y, and Z rotation parameters. See Animating Rotations for information about quaternion rotation.
The same interpolation technique used for linking to multiple parameters is also used for linking to an object's orientation — see Linking to Multiple Driving Parameters. The interpolator for multi-linked parameters computes "how far" it is from one of its relative values by using a distance metric; for orientation, the interpolator uses the orientation (quaternion) distance.
To link a parameter to an object's orientation
Do one of the following to select the parameters to which you want to link the orientation of an object:
Pick the object whose orientation you want to drive the linked parameter. Right-click to end the picking session.
After you have set up the link, an expression (l_interpOri( local.rotx, local.roty, local.rotz )) is set on the linked parameter.
Set the object's orientation, then set the linked parameter's value relative to the orientation, as described in Setting Relative Values for Multi-Linked Parameters.
Setting relative values maps the object's complete orientation (not the individual Euler angle values) to the linked parameter's value.
Now when you change the orientation of the object, the linked parameter changes as well.
After you have set the relative values, you can edit the falloff, as described in Editing the Falloff.
