Add a mask layer

Using a mask layer provides a simple way to selectively reveal portions of the layer or layers below it. Masking requires making one layer a mask layer and the layers below it masked layers.

You'll use the rectangular shape on the Stage to mask part of the road graphic and animation so that the animation fits better on the Stage.

1. On the Stage, with the Selection tool selected, click the rectangular shape below the road.
2. Drag the shape straight up and align the left edge of the shape with the left edge of the road.
3. Right-click (Windows) or Control-click (Macintosh) the Mask layer in the Timeline and select Mask from the context menu.

   The layer converts to a mask layer, indicated by a blue diamond-shaped icon. The layer immediately below the layer is linked to the mask layer. The masked layer's name is indented, and its icon changes to a blue layer icon.

4. In the Timeline, drag the Road layer to the Mask layer, placing it below the Car layer.

   The mask layer and the layers it masks are automatically locked.

5. To view the mask effect, select Control > Test Movie.
6. When you finish viewing the mask effect, close the SWF file window to return to your document.