Understanding the Brute-Force Animation Technique

If you've ever made a flip-book, you already know how to make a frame-by-frame animation. Each page in a flip-book contains a slightly different image so that when you fan through all the pages, the image is animated. That's basically what you're going to do in this hour. However, instead of drawing something different on each page of a book, you'll be drawing a different image in each keyframe of the Flash Timeline. Whether you draw each image on a page of the book or in a Flash keyframe, I call this the brute-force technique because it's manual and very involved.

In this hour you will learn about features and techniques of Flash that make the animation process easier. However, frame-by-frame animation isn't a "feature" of Flash; it's a technique that you implement by using Flash's features. I mention this because I doubt you'll find "frame-by-frame" anywhere in the Flash manual or help files.

Enough talk! In the following task you'll make a quick animation, and then we can discuss what you've built.

Try It Yourself: Make a Frame-by-Frame Animation

In this task you'll make an animation of a stick man taking a walk. Follow these steps:

1.	Draw a stick man by using only lines (no fills) and make sure everything is snapped together, as in Figure 7.1. Figure 7.1. In this stick man drawn with lines, lines are used because they are easier to modify than shape fills.
2.	Single-click just to the right of the keyframe dot in Layer 1 that is, click in the second cell of Layer 1.
3.	Select Insert, Timeline, Keyframe or press F6 to insert a keyframe in Frame 2 with a copy of the stick man graphic.
4.	To make a slight change to the stick man in Frame 2, first make sure that you are editing Frame 2. You should see the red current-frame marker in Frame 2. If it's not there, click in Frame 2 of the Timeline.
5.	Bend one leg of the stick man slightly and change the end point of the arm so it looks like it's swinging (as in Figure 7.2). Figure 7.2. In the second keyframe, you bend the stick man's leg in preparation for taking a step.
6.	If you want to preview what you have so far, use the scrub technique. Grab the red current-frame marker and drag it back and forth. Okay, there's not much yet, but you can see the stick man beginning to take a step.
7.	To create the third frame, click in Layer 1 right after Frame 2 and select Insert, Timeline, Keyframe to copy the contents of Frame 2 into the new keyframe in Frame 3.
8.	Make a slight change to the stick man bend the leg more and swing the arm more.
9.	Continue to insert keyframes, one at a time. Make an edit to each new frame to keep the arms and legs moving, and then select Insert, Timeline, Keyframe again.

Previewing an Animation Using Test Movie

There are three ways to watch an entire animation: scrubbing, playing, and testing. Scrubbing the red current-frame marker is a good way to preview as you work. The only problem with scrubbing is that the speed isn't consistent it is only as smooth as you scrub. To play an animation, you select Control, Play or use the Play option on the Controller toolbar or press Enter. However, as you'll see later (when creating buttons the user can click, special effects layers such as masks, and animating using movie clips), playing a movie doesn't always show you exactly what your viewers will see, so I strongly recommend that you avoid previewing by using Play. The best way to view an animation is by selecting Control, Test Movie.

Test Movie exports a .swf file into the folder where your file is saved, names this file the same as your file but with a .swf extension, and then launches the Flash Player program so that you can view the results. You'll see how this works when you first save your source .fla file into a new, empty folder. After you use Test Movie, the folder will contain an additional .swf file.

By the Way: Test Movie Versus Publishing

Selecting File, Publish or File, Publish Preview is equivalent to testing the movie. In addition to generating a .swf, it just creates the .html page to host it and (in the case of Publish Preview) immediately lets you view the results in the browser. I suppose this is even more accurate than test movie because you see the movie in the final format but test movie is quicker and only good while you're working.

By the Way: .swf Files

As you recall from Hour 1, "Basics," a .swf file (pronounced "swif") is an exported Flash file. This is the kind of file you put in web pages. It differs from the source Flash (.fla) file in that it is not editable. The critical concept is that a source file is a .fla file, and that's the file you need to keep. You can always export again to create a .swf (from a .fla), but you can't get an editable .fla from a .swf.

You might have noticed that when you're testing a movie, the menus change. That's because you're actually running Flash Player, which is a different program than Flash. Also, the movie loops by default, which is something you'll learn about later, when you publish a movie to the Web (in Hours 19, "Linking a Movie to the Web," and 24, "Publishing a Creation").

Editing One Keyframe at a Time

The concept behind the frame-by-frame animation technique is simple. You just put a keyframe on each frame. An entirely different image appears on each frame sometimes drastically different, sometimes only slightly different. The beauty is that you can put anything you want in one keyframe because it doesn't matter what's in the other keyframes.

Although frame-by-frame animation is a simple concept, it can be a lot of work. Imagine conventional animation, in which an artist must draw each frame even when only a slight change is necessary. It's detailed, meticulous work and, unfortunately, it's not really any easier in Flash, although Flash provides functions such as Undo that help. You need to realize that this technique is for situations that require it such as when you're working with something that has lots of details, such as an animation of someone walking (which, actually, is one of the hardest things to animate because we all know what it should look like). No other Flash animation technique gives you this level of control to change each frame.

Changing the Frame View Setting

Just because frame-by-frame animation is a lot of work doesn't mean you can't use a little help. One way to make the process a little easier is by changing the Frame View setting. In Figure 7.3 you can see the Frame View drop-down menu. If you select Preview, each keyframe in the Timeline is displayed as it appears on the Stage. Figure 7.4 shows the stick man animation with Frame View set to Preview. Preview lets you see all the frames of the animation without actually stepping through them. The Preview in Context setting draws the preview in the correct proportions (including blank whitespace), so the stick man would likely appear smaller.

Figure 7.3. The Frame View drop-down menu is available to change the size and character of the Timeline. You can make each frame larger or include a visual preview of the contents of the Stage in each frame.

Figure 7.4. The stick man animation is shown with Frame View set to Preview so that an image of the onscreen contents appears in each frame of the Timeline.

The Frame View settings don't actually change an animation. For example, if you set Frame View to Large, it just makes the Timeline take up more space within Flash; the user will never notice the difference. Also, you can change the Frame View setting any time and change it back without changing the file.

Using the Onion Skin Tools

Probably the greatest helpers for frame-by-frame animations are Flash's Onion Skin tools. The onion skin technique was originally developed for conventional animation. When an artist draws each frame by hand, she needs a way to judge how much change in the image is necessary from one frame to the next. She draws a frame on tracing paper (which has the translucency of onion skin) that is placed on top of the previous frame. That way, she can see through to the previous frame and draw the next image accordingly.

In Flash, the Onion Skin tools have the same effect, but of course you don't use real onion skin. Flash's Onion Skin feature allows you to edit one keyframe while viewing as many frames before or after the current frame as you want.

To begin working with the Onion Skin tools, open the stick man animation file and click the leftmost Onion Skin button at the bottom of the Timeline (see Figure 7.5). Select Large by clicking the Frame View drop-down menu that is just to the right of the Timeline's frame numbers. With Onion Skin turned on, you can place the red current-frame marker on any frame you want and edit that frame, and then you see a dim view of the other frames in the animation. Which frames appear depends on where you position the Start Onion Skin and End Onion Skin markers. These markers can be difficult to grab when you try to move them; I often find myself accidentally grabbing the current-frame marker. It's easiest to grab the markers when Frame View is set to Large.

Figure 7.5. When Onion Skin is turned on (via the leftmost button), you can see the contents of adjacent frames.

You would probably turn on Onion Skin while creating an animation (instead of after it's done). To practice, in the following task you'll try creating the stick man animation again this time with the help of Onion Skin.

Try It Yourself: Use Onion Skin to Help Create an Animation

In this task you'll use the Onion Skin feature to ensure natural motion in the way a stick man walks. Here are the steps:

1.	Start a new file and set Frame View to Large.
2.	Turn on Onion Skin. Notice that the Start and End Onion Skin markers (see Figure 7.6) cannot be moved beyond the beginning or end of the animation (because it's only one frame long at this point). Figure 7.6. The Onion Skin markers indicate how many frames are included in the Onion Skin view.
3.	Draw a stick man similar to the way you did in the previous task (using only lines).
4.	In Frame 2, select Insert, Timeline, Keyframe or press F6 to copy what was in the previous frame and paste it into the new keyframe.
5.	While editing Frame 2 (the red current-frame marker should be in Frame 2), drag the end of one leg of the stick man to move it to a different angle. This time, the position of the leg from Frame 1 is visible (though dimly), even though you can only edit the contents of Frame 2.
6.	In Frame 3, insert another keyframe. When you move the leg, you can judge how much to move it, based on the position of the leg in Frame 2.
7.	Continue to insert keyframes, one at a time. Make an edit to each new frame and then select Insert, Timeline, Keyframe again.
8.	When you have several frames, experiment with changing both the Start and End Onion Skin markers. By default, the markers are set to Onion 2, meaning you can see two frames ahead and two behind. I rarely use the End Onion Skin marker at all I just position it at the current-frame marker. I would rather see where I've been than where I'm headed. You can move the markers to several preset positions from the Modify Onion Markers drop-down menu (the rightmost Onion Skin button, pictured in Figure 7.7). Figure 7.7. The Modify Onion Markers drop-down menu has several preset options.

• Always Show Markers This option leaves a faint version of the markers visible in the Timeline even after you turn off Onion Skin.

• Anchor Onion This option locks the two markers where they are, no matter where the red current-frame marker is.

• Onion 2 This option sets the markers to two frames ahead and two frames behind.

• Onion 5 This option sets the markers to five frames ahead and five frames behind.

• Onion All This option moves the Start Onion Skin Marker to Frame 1 and the End Onion Skin Marker to your last frame.

Before we finish with Onion Skin, let's look at two remaining features: Onion Skin Outlines and Edit Multiple Frames. You can choose either Onion Skin or Onion Skin Outlines, but not both. Onion Skin Outlines displays the other frames within the Onion markers as outlines instead of as dim images. Outlines can be helpful when the dim view makes images difficult to distinguish.

Edit Multiple Frames is quite interesting because you don't commonly use it to produce an animation. In the previous task, you used onion skinning to see the contents of surrounding keyframes, but you were editing only one frame at a time the current frame. You could move the stick man's leg close to the faded image in the previous frame without affecting the previous frame. Edit Multiple Frames lets you edit the contents of all the frames within the Start Onion Skin and End Onion Skin markers. Generally, Edit Multiple Frames is useful for editing a finished animation. For example, if you have a finished animation for which you want to move the contents of every frame, Edit Multiple Frames is invaluable. In this situation, you just turn on Edit Multiple Frames, select Modify Onion Markers, Onion All, select everything on the Stage (or press Ctrl+A), and move everything anywhere you want.