Flash CS5: The Missing Manual

Changing Transparency with the Motion Editor

Now it's time to turn some of that Motion Editor theory to practice. By now, you know how to tween dimensions (Tweening a Symbol's Dimension Properties) and position (Making It Move with Motion Tweens); now you'll learn how to change the transparency of a tweened symbol. As shown in Figure 8-18, the Missing CD file 08-5_Tween_Alpha.fla shows an animated sign for a car company, but you can use your own symbol if you prefer. In the sample file, the sign spins and bounces as it gets bigger, giving the impression that it's coming at the audience. In the following steps, you adjust the transparency so that the sign goes from an alpha value of 20 percent to a value of 100 percent, making it completely opaque at the end of the motion.

Figure 8-18. The Motion Editor is made up of numerous subpanels. Each subpanel gives you access to tweenable properties. Here the Rotation Z property is set to 1800. You can click and type a value or drag to "scrub in" a value.

Note

Techies often refer to transparency as the alpha channel. Typically, computer video has RGB channels for red, green, and blue. To store information about the opacity and transparency of an image, programmers needed another channel, and they dubbed it the alpha channel, because they needed another letter and why not start at the beginning of the alphabet?

1. Drag the playhead to Frame 1, and ...