User Guide

CHAPTER 7
256
Working with Masks and Transparency
Applying effects to a mask
You can apply the following standard After Effects effects to a mask shape: Path Text,
Audio Waveform, Audio Spectrum, Stroke, Fill (closed paths only), and Smear (closed
paths only). You can apply the following After Effects Production Bundle effects to a mask
shape: Reshape (closed paths only), Vegas, and the Inner Outer Key (closed paths only).
The Production Bundle effect Particle Playground can also use a mask shape to define
effect boundaries.
You may also be able to use masks with effects from other manufacturers. To find out
where to get more information on the effects listed, see the index.
Creating visible lines and solid shapes from masks
To outline or fill a mask, apply the Stroke (outline) and/or the Fill effect. Each mask in a
layer can have different fill and stoke settings. You can apply an outline to an open or
closed mask path, but if you want to fill a mask, it must be a closed path. See “Working
with effects” on page 269 for information on using effects.
Controlling how masks in the same layer interact
Transfer modes for masks control how different masks within a layer interact with one
another. By default, all masks are set to Add, which combines the transparency values of
any masks that overlap on the same layer. You can apply one mode to each mask, but you
cannot change a mask’s mode over time.
The first mask you create interacts with the layer’s alpha channel. If that channel doesn’t
define the entire image as opaque, then the mask interacts with the layer frame. Each
additional mask you create interacts with masks located above it in the Timeline window
outline. The results of mask modes vary depending on the modes set for the masks higher
up in the outline. You can use mask modes only between masks in the same layer. For more
information on working with mask modes, see “Using mask modes” on page 257.
UG.book Page 256 Wednesday, February 21, 2001 12:05 PM