5

To delete a custom folder from a subcategory in the Library stack
µ
Control-click the folder in the Library stack, then choose Move to Trash from the shortcut
menu.
Note: You can also delete the folder from the Finder. The folder is stored in the
Users/username/Library/Application Support/Library/ folder.
Important: Deleting a custom object or folder cannot be undone.
To delete a custom folder from a category in the Library sidebar
µ
In the Finder, navigate to the Users/[username]/Library/Application
Support/Motion/Library/ folder, Control-click the folder, then choose Move to Trash from
the shortcut menu.
Using Masks to Create Transparency
When you create a mask to define transparency in a layer, you’re drawing a shape to use
as that layer’s alpha channel. Because a layer’s alpha channel is a grayscale channel, masks
are grayscale objects, where white defines solid areas, progressively darker levels of gray
define decreasingly opaque areas, and black defines areas of complete transparency. If
you choose View > Channels > Alpha to set the Canvas to display the alpha channel only,
you can see the grayscale alpha channel directly.
Object alpha channelMasked object
You can apply masks to layers that already have an alpha channel, to add to, subtract
from, intersect, or replace the layer’s original alpha channel.
Masking a Layer or Group
Use the mask tools to create different shapes with which to mask a layer or group. There
are five mask tools available that are analogous to the five shape drawing tools covered
earlier in this chapter:
• Rectangle Mask
• Circle Mask
1196 Chapter 20 Using Shapes, Masks, and Paint Strokes