0.1*$CEX*($F-1) ????

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I have recently enjoyed a tutorial on breaking polygons, and this is typed into the translate to move the poly away from the center. Could someone direct me to where I could learn about this command or explain it. I want to learn how to control it for key frame usage. It just runs the animation and I have no idea how to stop it until I want to use this effect.

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hi

So is: 0.1 is a constant, $CEX is the object's centroid position and $F will return the current frame number. If you take a look at the primitive sop you can see that the pivot has $CEX,Y,Z as values. Each node have a help card and there is a tab called locals. If you look into it you can learn something about the local variables that you can use with that node.
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So to put the equation in english, it just says to move the object in the direction of the line formed from the object's centroid to its origin. To make an expression keyframeable, you just substitute the part of it that you want to key with one of the keyframe expressions: linear(), cubic(), etc.

For this expression, note that ($F-1) is essentially a diagonal line slanted towards the right which has the value 0 at frame 1. So you could try replacing it with (linear()). Now go to the last frame in your animation. Key the parameter. Change the parameter from “expression” (dark grey) mode to “value” mode if it isn't already by clicking on the name of the parameter. Type in a new value, say 5. After you hit enter, the number will change because it then instantly evaluates to 0.1*$CEX*5. So can scope the channel to see how it looks and tweak the value of the key further. Note that you see that the graph doesn't evaluate to touch your keys though because it's graphing the result of the expression.
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Thank you both for your help. Both descriptions are great. The english version is easier to understand but the technical version teaches me what i need to know.
Thanks again.
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