I was looking for a simple way to alternate 2 layers for a simple flapping cape animation.

I came across this expression to set a layer to blink. I figured out how to modify it for the effect I wanted.

Add the following expressions to opacity:

Layer 1

blinkSpeed = 2;

t = (Math.cos (blinkSpeed*time*Math.PI*2)+1)/2;

v = linear(t, 0, 1, 0, 1);

Math.round(v)*100

Layer 1

blinkSpeed = 2;

t = (Math.cos (blinkSpeed*time*Math.PI*2)+1)/2;

v = linear(t, 1, 0, 1, 0);

Math.round(v)*100

Notice the change to the "v=linear" number order.

I'm sure this is out there somewhere but I couldn't find it.