Animating Mask Shape

So your mask needs to adjust over time. Don't most things in life? Not a problem. After Effects offers several functions for keyframing your masks. Let's get started by clicking the triangle by the Masks to open up the mask properties.

• Click the Mask Shape stopwatch to set a shape keyframe. You can also press Shift+Option+M (Shift+Alt+M) to set an initial keyframe on a selected mask

• Advance in the Timeline and modify your vertexes to make a new shape keyframe.

• Make the workspace as long as your shape mask animation and RAM preview to see After Effects interpolate the shape transformation.

• When modifying a Bezier handle, you will affect both the incoming and outgoing curves. To access one handle at a time, use the Convert Vertex Tool, and drag one of the handles. You can also hold down the Option key (Alt) to do the same.

• If you want to rejoin your handles, use the Convert Vertex Tool to convert the vertex to linear, then back to Bezier again.