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Random expression with exceptions
I didn’t find my answer on the web nor here so I’m asking directly :
I’d like to make a random expression which goes from 1 to 10 for instance but with exceptions like 2, 4 and 6. These exceptions could be changing so this is why I’m not doing a random expression based only on the other numbers.I tried to achieve it using if/else statements :
If random number = exception 1 add 1 to it
but first it’s quite messy and there are many flaws especially with several exceptions.Are you aware of a more efficient way?
Have a great weekend
UPDATE : I found the “while” statement could be, theoretically, the solution by looping the random expression until it gives a correct value, but when I use in AE, AE turns veryyy slow or even doesn’t calculate it due to a Timeout while waiting for the engine.
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4 Replies
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I think this will work
exceptions = [2,4,6];
randomSeed=time*thisComp.frameDuration;
result=Math.round(Math.random(10));
while(exceptions.indexOf(result)!=-1){
randomSeed+=Math.round(Math.random(100));
result=Math.round(Math.random(10));
}
resultAndrei
My Envato portfolio. -
Hi Andrei,
Thank you for the answer!
I tried to give your expression a shot in AE but I have several error messages :
– first “Math.random()” is not a function. I replaced them by simply “random()”
– “exceptions.indexOf” is undefined and since I’m not sure what this line is for I don’t know how to fix it. Any idea? -
Do you have After Effects 2019 or later? If yes, go to Project Settings>Expressions and set the Expression Engine to Javascript.
If you do not wish to change your Expression Engine to Javascript(I suggest you do), you can use this expression:
function include(arr, obj) {
for (var i = 0; i < arr.length; i++) {
if (arr[i] == obj) return true;
}
}exceptions = [2,4,6];
randomSeed=time*thisComp.frameDuration;
result=Math.round(random(10));
while(include(exceptions,result)){
randomSeed+=Math.round(random(100));
result=Math.round(random(10));
}
result
Andrei
My Envato portfolio. -
This works great!
Thanks for giving me the “no Javascript engine” version since I work on an older version of AE.
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