Using the Animation Constraints menu, you can apply constraints to objects. This menu also lets you select a target object. You can use the various constraints to limit the motion of objects, which is helpful as you begin to animate. If you're an animator, you should thank your lucky stars for controllers. Controllers offer power flexibility for animating objects-and just think of all those keys that you don't have to set by hand.
This chapter covered the basics of using the Expression controller. Using mathematical formulas to control the animation of an object's transformation and parameters offers lots of power. You can also use the values of one object to control another object.
In this chapter, you accomplished the following:
Constrained an object to the surface of another object using the Attachment and Surface constraints
Forced an object to travel along a path with the Path constraint
Controlled the position and orientation of objects with weighted Position and Orientation constraints
Shifted between two different controlling objects using the Link constraint
Followed objects with the LookAt constraint
Learned about the various controller types
Discovered how to assign controllers using the Motion panel and the Track View
Set default controllers in the Preference Settings dialog box
Examined the various controllers in several different categories
Saw a few examples of using controllers
Practiced building expressions in the Expression dialog box
Learned about expressions and what they can do
Reviewed the available operators, variables, and functions
Tried out examples of controlling object transformations and parameters
In the next chapter, you learn to use the Track View to display and manage all the details of the current scene.