Apple Motion 2 - Manual (Page 865)

Chapter 12 Using Shapes and Masks 865
Every time you move the playhead to a new frame and make a change to the mask’s
shape, a keyframe is automatically created in that shape’s Shape Animation parameter.
If you move the playhead directly on top of a previously existing keyframe, you change
the mask’s shape at that point without creating a new keyframe.
Note: You can also transform and shear masks as you would any other object. If you
move, rotate, scale, shear, or change the anchor point for a mask while animation
recording is enabled, you add keyframes to additional channels in the Keyframe Editor.
6 When you’ve finished animating the mask, disable Record (press A).
You can also create, delete, and edit the timing of a mask’s Shape Animation keyframes
directly in the Keyframe Editor. For simplicity, each change you make to a mask is
recorded as a single keyframe, no matter how many control points you edited. The
Shape Animation parameter only allows keyframes set to Constant—you cannot use
any other form of keyframe interpolation.
The process used to animate both masks and shapes is identical. To see an example of
shape animation, see “
Animating Shapes ” on page 847. For more information on
keyframing in general, see “ Keyframes and Curves ” on page 401.
Applying Image Masks to an Object
Another way you can create transparency in an object is by using image masks. An
image mask creates transparency in another object by deriving an alpha channel from
another object, such as a shape, text object, movie, or still image.
Note: You can use masks and image masks together.
Text object Layers Layers masked by text object
01112.book Page 865 Sunday, March 13, 2005 10:36 PM