Stop loop expression at certain time period

[Kevin Camp]

I think you’ll need to roll-your-own loop expression.

try this:

dur = 5; // value in seconds
if ( numKeys > 0 ) {
loopDur = key(numKeys).time - key(1).time;
if ( time < dur ) valueAtTime( time % loopDur ) else valueAtTime( dur % loopDur );
}

Kevin Camp
Art Director
KCPQ, KZJO & KRCW

[Krishna Moorthy]

Hi,, Thanks for your reply mate.

AE throws an error when I used your expression, the error is, “expected )”

Could you please explain the expression, so that I can figure out what is the issue with it.

Thank you!

[Kevin Camp]

the less-than sign was replaced by ‘<‘ when posting…

I also should have added the ‘else’ in case there were no keyframes…. i’ll try the expression with a performated tag:

dur = 5; // value in seconds
if ( numKeys > 0 ) {
	loopDur = key(numKeys).time - key(1).time;
	if ( time < dur ) valueAtTime( time % loopDur ) else valueAtTime( dur % loopDur );
} else {
	value;
}

essentially the expression is using the valueAtTime() function to build a loop. by using the modulus (that’s the % sign function) of the current time for a given period (in this case loopDur, that is derived by the times of the first an last keyframes), you can create your own looping expression.

using the if statement, it will loop until the time specified by the ‘dur’ variable.

valueAtTime( due % loopDur ) just sets the value (or point in the loop) to hold at that time specified by ‘dur’.

Kevin Camp
Art Director
KCPQ, KZJO & KRCW

[Suhair Vennakkad]

thank you Kevin Camp_it’s very usefull

dur = 15; // value in seconds

if ( numKeys > 0 ) {

loopDur = key(numKeys).time - key(1).time;

if ( time &lt; dur ) valueAtTime( time % loopDur ) else valueAtTime( dur % loopDur );

} else {

value;

}

[Colby Turybury]

How about the looping be based on number of loops instead of time. Say 10 loops. How would you go about that?

[Dan Ebberts]

That would be something like this:


nLoops = 10;
if (numKeys > 1){
loopDur = key(numKeys).time - key(1).time;
n = Math.floor((time - key(1).time)/loopDur);
if (n < nLoops){
t = (time - key(1).time)%loopDur;
valueAtTime(key(1).time + t);
}else{
valueAtTime(key(numKeys).time);
}
}else
value;


Dan

[Andy Engelkemier]

so I’m not great at math, which makes me not great at writing expressions. I get lost at the valueAtTime part. You know, the part that says what actually happens.

I’m not sure about the %. I don’t really understand how to practically apply what modulo is.

That being said. It works, but i need it to stop looping at the End of the loop. My loop is intentionally abrupt, so the beginning and end are opposite. I want to just say else value at key(2) (there are 3 keys) but not sure if that’s possible.