Apple Motion 2 - Manual (Page 855)

Chapter 12 Using Shapes and Masks 855
• Add: This is the default selection for new masks. Each new mask adds to the existing
alpha channel. This is useful for adding back regions of an image that other masks
are cutting out. In this example, both the rectangle and circle masks are creating
opaque regions.
• Subtract: Subtracts a mask from the alpha channel. This is useful for creating holes
in the middle of objects, or for masking out additional regions of an image that are
untouched by other masks. In this example, both the rectangle and circle masks are
creating transparent regions.
01112.book Page 855 Sunday, March 13, 2005 10:36 PM