Tag Archives: VFX

After Effects: Split-flap text animation

Here is a code snippet which allows you to animate text changes similar to a split-flap display using AfterEffects. The animation does not look exactly like those displays because I wanted a slightly different behavior for texts of different lengths. This is how the effect will look like (click on the following image to start the animation):
splitFlapDisplay

So how to do this in AfterEffects?

  1. Create a new text layer and add a slider control to the layer by searching for it in the Effects&Presets field.
  2. Now we have to enter an expression for the source text: open the layer properties and then the text property. Alt-click on the stop watch next to “Source Text”. Now, it should look like this:Split-Flap Display Tutorial 02
  3. Then enter the following code into the expression field (the field on the right which currently says “text.sourceText”):
    var oldText = "the old text";
    var newText = "new content";
    
    var result = "";
    var percentage = Math.min(Math.max(0,<code>effect("Slider Control")("Slider"</code>),100);
    //Iterate through charcodes
    var maxLength = Math.max(oldText.length, newText.length);
    for(var i=0; i<maxLength; i++) {
    	if(i> oldText.length-1) {
    		//The old text is shorter
    		var toomuch= maxLength-oldText.length;
    		var additional = percentage/100*toomuch;
    		if(i < oldText.length+ additional) {
    			result += String.fromCharCode(newText.charCodeAt(i));
    		}
    	} else if( i > newText.length-1) {
    		//The new text is shorter
    		var toomuch= maxLength-newText.length;
    		var additional = (100-percentage)/100*toomuch;
    		if(i < newText.length+ additional) {
    			result += String.fromCharCode(oldText.charCodeAt(i));
    		}
    	} else {
    		result += String.fromCharCode(oldText.charCodeAt(i) + percentage/100*(newText.charCodeAt(i)-oldText.charCodeAt(i)));
    	}
    }
    result
    
  4. Note: if you have started AfterEffects in a different language than English you will get an exception. This is because effect("Slider Control")("Slider") in line 5 cannot be found. Find the slider control in the text layer, write down the right names and enter them into line 5 (i.e. in German: effect("Einstellungen für Schieberegler")("Schieberegler") ).
  5. Change the variables oldText and newText to your desired values.
  6. Now you can animate the slider with values between 0 (old text) and 100 (new text).

You can also download an example project: