Let's see how this works. We have two variables that are set up when the movieclip is loaded: dir and speed. Dir is set to 1, -1 or 0 depending on whether we want the animation to move forward, backward or to stay still. When we rollover or rollout of the movieclip, the direction of the animation is reversed.
On each frame the script calculates a new tentative transparency value for the original picture. The nested Math.min and Math.max functions bound the value of the temp variable to between 0 and 100; this is crucial as these are the only reasonable values for the _alpha property. So all the script does is make the original picture opaque on rollover and clear on rollout. That's all there is to it.
|» Level Basic|
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|The author is a math enthusiast. He is currently studying Physics at McGill University.|
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