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Using the Checkbox expression control in After Effects

The Checkbox control is an expression control that works differently than the other controls in this group. This is because a Checkbox Control can only control two values. Therefore, it works like a true or false, on or off statement. If the box is checked, we return a 1. If it isn’t checked, we return a 0.

Let’s look at using this control with layer opacity as an example. With the control applied, set an expression for opacity. Then, pickwhip to the checkbox. We can multiply the expression times 100. Therefore, if the box is checked, we will see the layer. This is because the checkbox value is on, or 1. 1*100=100, or full opacity of 100%. If the checkbox is NOT checked, then we return a 0. 0*100=0, and at 0% opacity the layer is not showing.

Watch this short tutorial to see it in action: