Share
 
 

Animation Constraints

An animation constraint is a special type of controller that can help you automate the animation process. You can use constraints to control an object’s position, rotation, or scale through a binding relationship with another object.

A constraint requires an animated object and at least one target object. The target imposes specific animation limits on the constrained object.

For example, to quickly animate an airplane flying along a predefined path, you can use a Path constraint to restrict the airplane’s motion to a spline.

You can use keyframe animation to toggle the constraint’s binding relationship with its targets over a period of time.

Common uses for constraints include:

  • Linking one object to another over a period of time, such as a character’s hand picking up a baseball bat
  • Linking an object’s position or rotation to one or several objects
  • Keeping an object’s position between two or more objects
  • Constraining an object along a path or between multiple paths
  • Constraining an object to a surface
  • Making an object point toward another object
  • Keeping an object’s orientation in relation to another
Tip: You can use Schematic View to see all the Constraint relationships in a scene.

Using Constraints with Bones

Constraints can be applied to bones as long as an IK controller is not controlling the bones. If the bones have an assigned IK controller, you can only constrain the root of the hierarchy or chain.

Topics in this section
  • Attachment Constraint
    The Attachment constraint is a position constraint that attaches an object's position to a face on another object (the target object doesn't have to be a mesh, but must be convertible to a mesh).
  • Link Constraint
    The Link constraint causes an object to inherit the position, rotation, and scale of its target object. In effect, it allows you to animate a hierarchical relationship, so that the motion of an object to which the Link constraint is applied can be controlled by different objects in the scene throughout an animation.
  • LookAt Constraint
    The LookAt constraint controls an object’s orientation so that it’s always looking at another object or objects. It locks an object’s rotation so that one of its axes points toward the target object, or the weighted average of target positions. The LookAt axis points toward the target, while the Upnode axis defines which axis points upward. If the two coincide, a flipping behavior can result. This is similar to pointing a target camera straight up.
  • Orientation Constraint
    An Orientation constraint causes an object’s orientation to follow the orientation of a target object or averaged orientation of several target objects.
  • Path Constraint
    Use the Path constraint to restrict an object's movement along a spline or at an averaged distance among multiple splines.
  • Position Constraint
    Use the Position constraint to cause an object to follow the position of a target object or the weighted average position of several objects.
  • Surface Constraint
    The Surface constraint restricts an object to the surface of another object. Its controls include U and V Position settings as well as an alignment option.

Was this information helpful?