Author: Brian Judy
Date: October 26, 2006
Level: Beginner

The Continents application in the Explorer menu uses the alpha property to create fade effects while the animation is playing.  Fade effects are one of the most commonly used transitions in any motion designer's toolbox. Learning to animate a Movie Clip’s alpha property will allow you to produce this effect, giving you an important skill in developing engaging Flash projects.

• Beginning Flash
• layers
• arrange
• alpha
• movie clips
• keyframes

• Flash

• How to Adjust the Alpha
• Animating a Movie Clip’s Alpha Property

• myglife_plate_map.fla

Alpha is a property that controls the amount of transparency a graphic element(anything which is visible in Flash) has.  Transparency allows graphic elements behind, or on a layer below, to show through depending on how much trannsparency there is.  An alpha of 100% won’t let any graphics show through.  A 0% alpha will only show graphics that are behind or below.  An element with 0% will be invisible.

You can adjust a color’s alpha from the color picker. Click on one of the color chips in the Tools panel to display the color picker.

You can also adjust a color’s alpha from the Color Mixer.

The alpha property of a Movie Clip can be changed from the Properties panel when a Movie Clip is selected.  Make sure you select alpha from the Color dropdown.

 

 

The Continents Flash movie makes a lot of use of animated alpha channels to create the fade transitions between two time periods.

1. Open glife_plate_map.fla
2. Move the frame dragger to frame 2. You should now see the screen for the movie.
3. Double click the center for the map.
4. Your screen should now look something like this…
   
   Each layer on the timeline represents a phase of the continental shift overtime.  The blue bars indicate an animation.

   .
   

5. Drag the red timeline scroller back and forth along the frames.  Notice how the animation moves.

6. Click the lock next for the layer named '-575'.  The lock should now be replaced by a dot.  This allows you to edit the layer.
7. Click on the map.  You should now see a Properties panel that looks like this.  Notice the alpha is set to 9%.
   
   
   

    

8. If you move the frame dragger to frame 9 and click on the globe again you’ll see that the alpha is not set. This is the same as 100%.  The frames in between will have an alpha between 9% and 100%.
9. While still on frame 9, click the drop down next to 100% in the Properties panel and drag the slider up and down.  Notice how the continents fade.
10. Try adjusting a Movie Clip's alpha at any keyframe to see how the movie changes.

There are other uses of alpha manipulation in this Flash application.  Run it from the website and see how many you can discover.