Flash Lecture 3: Masks

1. Flash Lecture 3:Masks Dr. Harry Witchel

2. Masks • Masking is a 2 layer system (like guides) in which the upper layer controls what part of the lower layer can be seen • This technique is useful for appearances/disappearances, “spotlight” effects and “magnifier” effects • The Upper layer is mask (e.g., black) • Each pixel will be all or none • It is invisible in final movie • Mask is a layer property (right click to make a layer a mask) • Parts of the lower layer are revealed by what is present above • Either layer can be moving (tweens) • Masking does not work until you make a “published” version of the movie (i.e., control-return)

3. Appear Effect Using a Mask

4. Spotlight Effect Using a Mask

5. Exercise: Make an ECG movie with a mask • 3 layers, each 40 frames • Bottom layer: Graph paper lines • Middle layer: masked layer of ECG trace. • This layer has no animation or tween on it • In frame 1 draw the ECG trace with the pencil tool • Top layer: Mask layer with motion tween. • In frame one make a symbol that is a rectangle as large as the stage, and locate it to the left of the stage • In frame 40 make another keyframe and move the box symbol rightward so that it covers the entire stage • Tween the frames between frames 1 & 40 (either a motion tween or a classic tween) • Right click on top layer and middle layer and select properties, then make top layer a mask and middle layer masked • When you run the movie, you should see blank graph paper, and then the ECG trace should appear on it