Create masks

You can create shapes and masks with the Rectangle and Pen tool in After Effects. When you create a mask or shape layer, keep the following things in mind:

• If a layer is selected in the Timeline panel, you are creating a mask.
• If a layer is not selected in the Timeline panel, you are creating a shape layer. See Creating shapes in After Effects.

You can create one or more masks for each layer in a composition using any of the following methods:

Points to keep in mind

• When you create masks on a layer, the mask names appear in the Timeline panel outline in the order in which you create the masks. To organize and keep track of your masks, rename them.

• To rename a mask, select it and press Enter (Windows) or Return (macOS), or right-click (Windows) or control+click (macOS) the mask name and choose Rename.

• When you create additional masks for one layer in the Layer panel, make sure that the Target menu in the Layer panel is set to None; otherwise, you replace the targeted mask instead of creating a mask. You can also lock a mask to prevent changes to it.

• When creating or editing masks, look in the Info panel for information such as the mask name and the number of vertices in the mask.

Create a mask by dragging with shape tools

The shape tools are the Rectangle , Rounded Rectangle , Ellipse , Polygon , and Star tools.

A polygon is a star without an Inner Radius or Inner Roundness property. So, the name of the shape created for a polygon or a star is the same: polystar.

You can create a mask by dragging with a shape tool on a selected layer in the Composition or Layer panel.

To learn more, see how to create shapes by dragging shape tools.

Create a rectangular or elliptical mask numerically

Create a mask from channel values with Auto-trace

1. You can convert the alpha, red, green, blue, or luminance channel of a layer to one or more masks by using the Auto-trace command.
   
2. Auto-trace creates as many Bezier masks as necessary to outline the specified channel values in the layer.
   
3. It also creates masks with the smallest number of vertices possible while conforming to the settings that you choose.
   
4. You can modify a mask created with Auto-trace as you would any other mask, and you can link its path to other path types, such as shape paths on a shape layer, using expressions.

When you apply Auto-trace, affected layers are automatically set to Best Quality to ensure accurate results.

Create a mask of the size of the layer

Create masks from text characters

The Create Shapes From Text command extracts the outlines for each character, creates shapes from the outlines, and puts the shapes on a new shape layer. You can then use these shapes as you would any other shapes.

The Create Masks From Text command extracts the outlines for each character, creates masks from the outlines, and puts the masks on a new solid-color layer. You can then use these masks as you would any other masks.

Points to note

• The Video switch for the text layer is turned off.
• The new solid-color layer is created at the top of the layer stacking order.
• For characters that consist of compound paths—such as i and e—multiple masks are created and combined with the Subtract mask mode.

Create a mask from a motionpath

You can copy position keyframes, anchor point keyframes, or an effect control point’s position keyframes and paste those keyframes into a selected mask path or shape path. When you create mask paths or shape paths from motion paths, make sure that you copy keyframes from a single Position property only—do not copy the keyframes of any other property.

Create a mask path from a motion path