1. Introduction
Flash provides several methods for creating
animation. In addition to shape and motion tweening, you can create
frame-by-frame animations. The frame-by-frame method is derived from
the traditional animation process whereby the content is redrawn on
each frame with slight differences from the last frame. When these
frames are played in sequence, there is an illusion of movement. In
Flash, you utilize keyframes in the Timeline to accomplish this. A keyframe
defines a change to the artwork placed on the Stage. There are a number
of ways to create and edit keyframes, as they are editable objects.
Keyframes can be moved, copied, and pasted to and from any Timeline in
your Flash movie or between different Flash documents. Frame-by-frame
animations can be previewed in the Flash development environment so you
can quickly see the results and check your work as you animate. They
can also be viewed in the Flash Player using the Test Movie options.
Additionally, there is an Onion Skin mode
that allows you to see the active frame in context to the frames around
it, making it easier to fine-tune keyframe changes. The versatility of
the Timeline and the strength of the Flash Player allow you to
implement animation in your movie and give it life.
2. Understanding Frame-by-Frame Animation
Animation is the illusion of
movement. It is comprised of a series of pictures, each slightly
different from the last, that when played sequentially imply movement.
Motion pictures work the same way. What you see when you view a film is
a long strip of images played at specific intervals. In this way, the
content in the pictures moves and seems to imitate real life.
Traditional cell animators draw a picture
onto a frame of celluloid and then draw the same thing onto the next
frame but with slight changes made to the drawing. Static parts of the
scene (such as a background) are copied and only the objects that
change are redrawn. In this way the process is more efficient.
The principles for animating in Flash have derived
from this process. In Flash, you create frame-by-frame animations in
the Timeline through the use of keyframes. Each keyframe defines a
change on the Stage, and when played in succession, the content can
seem to evolve, or move. When you export your movie, Flash will play
these frames in succession at specific intervals depending on the frame
rate you set. A good introduction to this concept, as well as the
basics of animation, is the dissection a character walk cycle. When
human beings walk, they are essentially repeating the same motion over
and over again. In an animated walk cycle, the same thing occurs,
though instead of drawing the cycle over and over again, the motion is
spaced out so that the last frame (the last image drawn) meets up with
the first frame. If this animation is looped, the character will seem
to walk perpetually.
Frame 1
Frame 2
Frame 3
Frame 4
Frame 5
Frame 6
Frame 7
Frame 8
