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Moving a mask and panning a layer behind a mask


    You can adjust the area that displays through a mask by either moving the mask in the Layer or Composition window or panning (moving) the layer behind the mask in the Composition window. When you move a mask, the mask layer's Position values remain constant, and the mask moves in relation to other objects in the Composition window.

    When you use the Pan Behind tool to pan a layer behind a mask, the mask's position remains constant in the Composition window, but changes in the Layer window. The masked layer's Position values change in relation to the composition. As you pan past the edges of the layer's frame, the layer's Mask Shape values also change. Using the Pan Behind tool saves steps; without it, you would have to change the masked layer's Position and Mask Shape properties manually. You can animate a layer panning behind another layer by setting keyframes for the masked layer's Position and Mask Shape properties (see Setting keyframes).

    When you use the Pan Behind tool in the Composition window, After Effects automatically makes two adjustments for you. In the Layer window, the mask is moved in relation to its layer (top), while in the Composition window, the layer is moved in relation to the composition (bottom).
    When you use the Pan Behind tool in the Composition window, After Effects automatically makes two adjustments for you. In the Layer window, the mask is moved in relation to its layer (top), while in the Composition window, the layer is moved in relation to the composition (bottom).

To move a mask:

  1. Select the mask or masks you want to move. See Selecting masks and control points for information on selecting masks.
  2. In the Composition window, drag the mask or masks to a new location. To constrain the movement of the mask or masks to horizontal or vertical, press Shift after you start dragging.

To pan a layer behind its mask:

  1. Select the Pan Behind tool in the toolbox (the Pan Behind icon).
  2. Click inside the mask area in the Composition window and drag the layer to a new position.