AfterEffects

Create a mask from a motion path

You can copy position keyframes, anchor point keyframes, or an effect control point’s position keyframes and paste those keyframes on a selected mask. This is useful for creating animations that follow the edges of a mask. When you create masks from motion paths, make sure that you copy keyframes from a single position property only—do not copy the keyframes of any other property.

The motion path of the spaceship (top) is copied to the background layer (bottom left) and used by the Vegas effect (bottom right).

  1. In the Timeline panel, click the name of the Position property or Anchor Point property from which you want to copy the motion path. (This selects all keyframes. To select only some of the motion path’s keyframes, Shift-click them.)
  2. Choose Edit > Copy.
  3. To create a new mask, select the layer on which to create the mask, and choose Layer > Mask > New Mask.
  4. In the Timeline panel, click the name of the Mask Path property for the mask to which to paste the motion path keyframes.
  5. Choose Edit > Paste.
    Selecting and copying Position keyframes (left); then pasting them in the selected Mask Path property (right)