The greatest strength of Macromedia Flash is speed. It offers a significant decrease in production time that despite the limitations of the software's signature style cannot be ignored. This tutorial will focus on a technique available in Flash that allows very simple animation to be used to create complex effects and easily modified and reused action.
Figure 1 A sketch from Robot Republic
1. GENERAL CONCEPTS Each symbol created in Flash can be used almost like a miniature scene that can contain other symbols and animation. So if you have a symbol on the stage that has simple animation on it - and it contains another symbol that is animated - which contains yet another symbol that is animated...the result on the stage can be quite complex. This could be used on a machine whose moving parts contain other moving parts or a character whose head symbol contains other symbols with animated eyes and lip-sync.
The technique requires good organisation or it is easy to lose track of what is animating and when. It is important to understand how each of the symbol types and keyframing methods work. The tutorial will discuss the general concepts involved using a simple example and demonstrate how nested symbols were used to create some of the robot animation in Robot Republic.
A potential drawback is that it can make a scene quite processor intensive. For video formats this is not a problem but should be kept in mind if you want to avoid choppy playback as SWF.
TIMELINE: The timeline organises and controls a movie's content over time in layers and frames.
MAIN MOVIE: The base timeline of the document.
SYMBOLS: A symbol is a graphic, button, or movie clip that you create in Flash and can reuse throughout your movie or in other movies. Any symbol you create automatically becomes part of the library for the current document. Each symbol has a unique timeline and stage, complete with layers. When you create a symbol you choose the symbol type depending on how you want to use the symbol in the movie.
MOVIE CLIPS: Movie clips are used to create reusable peices of animation that play independently of the main movie's timeline. These can contain interactive elements.
BUTTONS: Button symbols are used to create interactive buttons that respond to user input.
GRAPHICS: Graphic symbols are used for static images or reusable peices of animation that are tied the to the timeline of the main movie. Interactive controls and sounds won't work with a graphic symbol.
2. EXAMPLE The simplest demonstration of nested symbols is one animated symbol containing another animated symbol. Graphic symbols are the easiest to use for this method as they are tied to the timeline of the main movie.
The simplest example is an eye blink inside an animated head symbol.
CHAR01: The symbol containing all the elements of the character, in this case the head and ponytail.
HEAD: This symbol contains any elements that remain anchored to the head, in this case fringe animation and eye symbol.
Then the head and ponytail movement are animated. Combined with the animation inside the symbols the result is a single piece of animation. Once animated the blink can be used in combination with any head move.
3. PRACTICAL APPLICATION This method is best used for character animation where one symbol contains all the elements of a character. That way the symbol can be moved around the scene, scaled, rotated or flipped, keyed to start at any frame or dropped into new scenes.
It is convenient for lip sync: the mouths, once matched to the soundtrack, always match to the movement of the head because they are contained within that symbol.
4. THE NTH DEGREE This method can be taken as far as you like. For Robot Republic it was used to combine some very basic animation to create a complex effect. For the dizbot's final scene the following combination was used.