Expression to randomly change color of individual characters of a text layer

[Yoan Boisjoli]

Guttentag Vlad!

I managed to do it via multiple text fill color (RGB) animators (one for each color).

Then I added an expression selector that goes like this to aim at each character:

(textIndex % 5 == 0) ? 100 : 0; //5 is the amount of color choices and 0 is the char index

The zero here is the one I’m changing on each animators.
Then I’m having the colors changing every 5 frames via an expression on the color property of the color animator.

seedRandom(index, true); // Ensures each layer has a unique random sequence
var colors = [
    effect("Color Control")(1),
	effect("Color Control 2")(1),
	effect("Color Control 3")(1),
	effect("Color Control 4")(1),
	effect("Color Control 5")(1)
];
colors[Math.floor(timeToFrames(time) / 5 + random(0, 5)) % colors.length]

I’m uploading the after effects file. Hope it helps !

ColorCharacter-1.aep 101 KB After Effects Project Files - Click to view

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Screenshot-2025-03-11-143329.png 141 KB Image File - Click to view

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[Dan Ebberts]

This Source Text expression appears to work:

numFrames = 5; // change colors every 5 frames
c1 = effect("Color Control 1")("Color");
c2 = effect("Color Control 2")("Color");
c3 = effect("Color Control 3")("Color");
c4 = effect("Color Control 4")("Color");
c5 = effect("Color Control 5")("Color");
colors = [c1,c2,c3,c4,c5];
f = timeToFrames(time);
seed = Math.floor(f/numFrames);
seedRandom(seed,true);
myExpr = "style";
for (i = 0; i < value.length; i++){
  myExpr += ".setFillColor(colors[Math.floor(random(colors.length))]," + i + ",1)";
}
eval(myExpr)

[Yoan Boisjoli]

Geez Dan! I took the complicated route ! hahaha yeah that works perfectly.

Is this using the new Per Character expression in 2025?

[Vlad Mecne]

Hi Dan, Yoan,

Both killing it. Wasn’t to make Dan’s expression work but may need to take a second stab at it.

Yoan – yours work fine but somehow the frequency of change isn’t applying the same to every character. Some letters change every other frames or around, others fine. AE file is attached if helpful.

Keeping at it and letting you know once something works well.

Danke!

Yoan-250311.aep 204 KB After Effects Project Files - Click to view

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[Vlad Mecne]

@Dan tried yours again – working really well. Many thanks!

Is there a way for the next color pick of each letter to not repeat the color it’s already using. Something like Color N+1 not equal to Color N?

Again thanks so much for helping out 🙂

[Dan Ebberts]

Do you mean so that each letter has a color different than the one next to it, or so that a letter doesn’t get the same color for two consecutive periods?

[Vlad Mecne]

So that a letter doesn’t get the same color for two consecutive periods.

[Dan Ebberts]

That’s considerably more complicated and will bog down in a longer comp because of the additional processing that needs to happen at each successive frame. Try this:

numFrames = 5; // change colors every 5 frames
c1 = effect("Color Control 1")("Color");
c2 = effect("Color Control 2")("Color");
c3 = effect("Color Control 3")("Color");
c4 = effect("Color Control 4")("Color");
c5 = effect("Color Control 5")("Color");
colors = [c1,c2,c3,c4,c5];
f = timeToFrames(time);
curPeriod = Math.floor(f/numFrames);
colorIdx = [];
seedRandom(0,true);
for (i = 0; i < value.length; i++){
  colorIdx.push(Math.floor(random(colors.length)));
}
i = 1;
while (i <= curPeriod){
  seedRandom(i,true);
  for (j = 0; j < value.length; j++){
    temp = colorIdx[j] + Math.floor(random(colors.length-1)) + 1;
    colorIdx[j] = temp%colors.length;
  }
  i++;
}
myExpr = "style";
for (i = 0; i < value.length; i++){
  myExpr += ".setFillColor(colors[colorIdx[" + i + "]]," + i + ",1)";
}
eval(myExpr)