Creating a bulge between two layers

Use an expression to synchronize the Bulge Center parameter of the Bulge effect in one layer with the position of another layer. For example, you can create an effect that looks like a magnifying glass moving over a layer, with the contents under the magnifying glass bulging as the lens (that is, the overlying layer) moves. This expression uses the fromWorld element, which makes the expression work correctly regardless of whether you move the magnifying glass layer or the underlying layer. You can rotate or scale the underlying layer and the expression stays intact.

You can also use other effects, such as Ripple, with this expression.

To create a bulge between two layers:

1. Start with two layers. Make one layer a magnifying glass or similar object with a hole in the middle and name it Magnifier.
2. Create a motion path for the magnifying glass layer.
3. Apply the Bulge effect to the other layer.
4. Select the Bulge effect's Bulge Center property in the Timeline window and choose Animation > Add Expression.
5. Select the default expression text and type the following:
fromWorld(thisComp.layer("Magnifier").position)