GDT 260 Animation for the Web: Winter 2002
2.21.02
Masks
Download the files needed for the demos:
Masks allow portions of content to be selectively shown and hidden.
- Where there is a shape on a mask layer, masked layer(s) shows through
- Where there is nothing on a mask layer, masked layer(s) is hidden
- Masks can apply to more than one layer at a time, as long as all the layers are directly below the mask
- Mask layers can be tweened
- Mask layers CAN'T have motion guides
- Mask layers can be made up of text, any shape or any symbol
- Movie clips on mask layers are static, however animated graphic symbols will play
- Movie clips on mask layers CAN'T be accessed or controlled with actionscript
- Buttons on mask layers will not work
Contrary to what the textbook states on page 275, masks DO NOT require that everything be converted to symbols in order to work.
Adding a Mask
- Add a new layer above the layer to be masked. Masks are always above the layers they are masking
- Draw your masking shape. Remember that the positive space of your mask is the area that will be revealed on the masked layers
- Control-click on the mask layer, and select "Mask" from the menu. The current layer will be converted to a mask, and the layer below will be automatically masked. Additionally, both layers are automatically locked. Unless both layers are locked, the mask effect doesn't display within the authoring environment, but will appear in the exported movie
- To add more layers to be masked, make sure they're directly below the existed masked layer, and Option-click the layer
Masking Effects with Bitmaps
This is a bit of a misnomer in the book. We've already done this - a broken apart bitmap is a shape filled with a bitmap. We're simply modifying the shape.
- File > Import to import the bitmap
- Modify > Break Apart
- Modify the shape as you see fit
Setting Compression for Bitmaps
- Select the bitmap in the library
- Library Options menu > Properties
- Uncheck "Use imported JPEG data" and enter a compression amount
