After Effects masks

[dennisb33002902]

An issue with masks. How to create a stationary mask.

I create a layer with a simple graphic with a motion path, a simple up and down. I want the simple graphic to come out of (from behind) a mask. The mask I create following the typical way to create a mask, follows the motion path. I want the mask to stay stationary. How to create a typical mask that stays stationary on  a layer with a motion path. Thanks

[Justin Taylor-Hyper Brew · Accepted solution]

What you want is a Track Matte. Set this up by creating a blank solid on a layer above, create a mask on that layer. Now set your layer you want masked to Alpha Matte. Now you can move your layer around and the mask will stay put.