Much as I hate to make this expression more complicated, I've been observing butterfly motion, and I've realized that it differs from what's generated in the expression in one key way. The wings don't move in a sine wave pattern. Rather they "pop," that is, they move down and up rather qui...

Here's a new version of the expression which is a little less incomprehensible, and a new version of the question, in case the best solution is to start again from scratch: Frequency=comp("Comp 1").layer("B_Controls").effect("Flap_Freq")("Slider")*6; Amplitude...

I've posted this on the AE forum over at Adobe, but I'd love to see what you guys can come up with (though many of us are regulars over there already). This one suddenly got a lot more difficult than I thought. I'm animating a butterfly's wings. So, I used a cosine function to drive the flapping, an...