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About Franimate!

Franimate! is a program for animating fractals like the ones created by Fractalina. The animations are defined by saying where it should be at a few key points in time ("key frames").

If you want to see it in action now, go directly to the applet: Franimate!.

How Animations are Described

In order to describe where an animation goes Franimate! uses "key frames". Each key frame is it's own Fractalina window, describing the fractal that will be one of the frames that the animation goes through. An animation must have at least two key frames, the first and last frames of the animation, and can have more in between, to give finer control over the animation.

Key frames are like check points: Franimate! can decide how to go between key frames, but it must end up at each key frame in order.

The number of frames between each pair of key frames is supplied by the user (see below). Thus Franimate! will satisfy another constraint: not only will it always go through key frames, but the distance, in frames, between them is specified.

Franimate! generates the frames between pairs of key frames by linearly interpolation. That is, the change in parameters between the key frames is equally divided among frames in between.

As an example, imagine having two key frames in which the only difference is the placement of one transformation: in the first it's at (0,0), in the second it's at (8,8). If one frame is between these key frames, it will have the transformation at (4,4). Similarly, if there are three frames they will have (2,2), (4,4), and, (6,6).

Setting-Up and Making an Animation

Adding and removing key frames:

When Franimate is started two key frames will pop up (labeled 1 and 2). For a simple animation (which goes from one fractal directly to another) these are all that's needed.

To add a key frame, enter the number of the frame just after the one to be added in the text box right of "before:". Then press "Add Key Frame". For instance, if you have key frames 1, 2, and 3, to add a key frame between 2 and 3 enter "3" in the box and press the button. a new key frame 3 will come up, and the old 3 will be moved to 4. (Another way of looking at this: enter in the text box the number of the new key frame.)

To remove a key frame, enter the number of the key frame to be removed in the text box right of "number:", then press "Remove Key Frame".

Changing the number of iterations and size:

The size of the animation (in pixels, but not always real screen pixels) can be changed from the Options window. To get the Options window press the button labeled "Options" in the main control panel. After you have changed values, remember to press "Accept", or the new values won't be registered. When setting the size of the animation, remember that the memory usage to store each frame goes up as the square of the size (memory can be important on some systems).

Also in the Options window is the number of iterations per frame. Since each iteration adds a point to the fractal, the number of iterations corresponds to how complete the image is. A few thousand iterations is usually enough, but it depends a lot on the fractal.

Choosing the number of frames:

There are two ways to choose the number of frames in between each pair of key frames. If you want the same number of frames between each pair (or you only have two key frames), set the number in the text box just right of "with". The default is 4.

If you want to specify the number of frames between pairs of key frames, press the "set up" button, and the Set Up Animation window will pop up. Each key frame is listed, and in between each pair is a text box. Enter the number of frames in between the two adjacent key frames into this box . If you open the Set Up Animation window and then change your mind, just press "cancel".

Making an animation:

Once the animation is set up it is easy to make it. If you have a Set Up Animation window open, press the "Make Animation" button there. Otherwise, press the "Make Animation" button in the main window. You will see each frame as it's generated.

Playing an Animation

The play button and scrollbar:

To play back an animation after it has been made, press the "Play" button. The scrollbar just above "Play" corresponds to which frame is being displayed. Notice that the scrollbar moves while the animation is being played, and that you can set the frame shown by changing the scrollbar.

Bounces and delay:

The "number of bounces per showing", and "delay between frames" can be found in the Options window. The number of bounces is the number of times the animation plays backwards or forwards (it will bounce back and forth if this is more that 1). The frame delay is the amount of time to sleep after playing a frame.

Dumping an animation to GIF files:

If the security manager allows file access (usually in the stand alone program, but usually not in an applet) you can dump the frames of an animation to GIF files. When the "GIF dump" button is pressed Franimate! will try to dump each frame into a file called frmn.gif, where n is the frame number. Once you have the gif frame images you can use a utility such as GIFMerge to combine them into an animated gif.a The gif dump function uses the excellent GIFEncoder class by Addam Doppelt.


Since each frame is stored as a Java Image, the memory requirements can rise rapidly with the size of the animation. However, there is no set way that Images are stored, so there is no way to know the memory usage. We have had the most trouble with Unix systems, in which Images are stored in the X manager. Interestingly memory doesn't seem to be an issue on PCs (including Macs). When memory runs out each system handles it in it's own way. (Unix systems tend to force the JVM to quit without a message.)

In the Options window you have to press "Accept" or the new values won't register. This is not actually a bug, it's here so people won't write about it.

If you find any bugs not listed here, please email the author.

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This page was created by Noah Goodman.
Comments to: webmaster@geom.umn.edu
Created: Sep 23 1996 --- Last modified: Tue Oct 8 11:34:01 1996