Masking is a way of selectively blocking areas of a layer. The technique allows an array of effects by hiding objects under a mask, animating the mask or object under the mask, or by placing multiple masks in a scene. In Flash, effects such as a spotlight that "illuminates" objects on the stage or a magnifying glass that appears to enlarge objects as it passes over them are not only possible but also simple to design with masks.

You create masks on mask layers, which differ from the two other types of layers found in Flash: motion guide layers and normal layers. A mask layer contains a filled shape that blocks off, or masks, objects on at least one other layer to which it is linked. You can link more than one layer to a single mask layer.

This article provides the steps to create a simple mask, then discusses using a mask to create a moving "spotlight." The article assumes mastery of beginning Flash concepts such as adding and naming layers, drawing objects, converting objects into symbols, adding simple actions, and creating tweening animation.

Creating a mask

Creating a spotlight effect with a mask

Add the background to a layer

Add the office graphic to a layer and align the instances

Create the spotlight animation on a mask layer

Add an action to play the movie continuously

Add add another instance and change the level of brightness

Summary

Stephanie Gowin Stephanie Gowin is a senior instructional designer for Macromedia. 6 July 2001 Flash, mask, spotlight effect 9814