Apple Motion 4 - Manual (Page 1280)

In this example, a mask is tracked to a moving car so that the car can be isolated from
the rest of the clip. The illustration on the left shows the original unmodified clip. In the
illustration on the right, the tracked mask isolates the car, allowing separate effects to be
applied to the car and its background even though they are part of the same image. The
mask is “protecting” the car from the effects of the heavy blur and desaturation.
Note: As with all behaviors, you can drag or copy (Option-drag) a Track Points behavior
to a new shape in the Layers tab. When you apply the behavior to a new shape, the
trackers are automatically applied to the control points of the new shape. If the new
shape has more control points than the originally tracked shape, only the original track
points are applied. For example, if the originally tracked shape has three control points,
and the new shape has five controls points, trackers are applied to the first three control
points of the new shape. If the new shape has fewer control points than the originally
tracked shape, trackers are applied to the existing points on the new shape. For example,
if the originally tracked shape has five controls points, and the new shape has three
control points, the first three trackers from the original shape are applied to the three
control points of the new shape.
Using a Shape Object as the Animation Source
This section provides a brief overview of using the Track Points behavior to apply the
animation of a layer (another shape, in this example) to the vertices of a shape or mask.
Applying the animation of one animated shape to another is an easy way to quickly create
fun, complimentary animations in which the objects appear to “play” with each other.
For this workflow, your project must contain an object that is animated with keyframes
or behaviors.
To apply the animation of a shape to the control points of another shape or mask
1 In a project that contains two shapes, animate one of the shapes using keyframes or a
Basic Motion behavior.
In this example, a simple line shape is animated with the Spin behavior.
For more information about animating with keyframes, see Animating in the Canvas . For
more information about the Basic Motion behaviors, see Basic Motion Behaviors .
1280 Chapter 19 Motion Tracking