#43 Putting Animation Inside Symbols
Whenever you're in symbol-editing mode, you might notice that all of the information in the Timeline disappears. That's because when you edit a symbol, you stop seeing your movie's Timeline and start seeing that symbol's timeline. Every symbol in Flash has its own internal timeline. (As you saw in #27, the one inside button symbols is greatly simplified, but it's a timeline nonetheless.)
The significance of symbol-specific timelines is that they allow you to put animation inside a symbol. Because instances of symbols appear in a movie's Timeline, and because instances of other symbols may appear in a symbol's timeline, it's possible (and actually common) to have several different levels of animation going on at once.
For example, suppose you want to animate a person running across the Stage. If you had to do this frame by frame, it would take you forever, but the use of animated symbols streamlines the process.
Here's all you'd have to do:
- Create a new movie-clip symbol and give it a descriptive name such as m_running.
Go into symbol-editing mode and animate the running person within m_running's timeline (not in the movie's Timeline).
You need only animate one cycle (that is, left foot forward and right foot forward). Make the cycle smooth enough that it can loop repeatedly without it being apparent where the cycle begins and ends (Figure 43a).
Figure 43a This frame-by-frame animation was created inside a movie-clip symbol.
- Drag an instance of m_running onto the movie's Stage.
- Motion-tween the instance to make it travel across the Stage.
- Test or preview the movie. You'll see two levels of animation going on at once: the animation within the symbol of the person running in place, and the animation outside the symbol of the running person moving across the Stage (Figure 43b).
Figure 43b As this person runs across the Stage, two levels of animation are going on at once.
Placing animation inside symbols is powerful and convenient, especially if you're creating an interactive movie in which the action is different every time. The Timeline for many interactive movies is only one frame long, because all of the movie's possible animation is contained within the symbols in the Library.