Reshaping a mask in After Effects is primarily done by directly manipulating its points and handles, or by scaling and rotating the entire mask. Here's a breakdown of the process:
Direct Manipulation of Mask Points
- Select the Layer: In the timeline panel, select the layer containing the mask you want to reshape.
- Select the Mask: In the Composition panel, select the mask itself. You can do this by clicking on the mask path. Alternatively, in the Timeline panel, expand the layer properties, then expand "Masks," and select the specific mask you want to edit.
- Use the Selection Tool (V): Make sure the Selection tool (V) is active. This is your primary tool for manipulating mask points.
- Move Mask Points: Click and drag individual mask points to reposition them.
- Adjust Handles: Click on the handles extending from each mask point to adjust the curvature of the mask path. These handles control Bezier curves. Experiment with dragging the handles to understand how they affect the shape.
- Add or Delete Points:
- Add: If your pen tool is active, hovering over the existing mask path will change your cursor. Click on the mask path to add a new point.
- Delete: You can use the Delete Vertex Tool (found by clicking and holding the Pen Tool) to remove points. Select a point and click it with the Delete Vertex Tool. Alternatively, with a mask point selected, hit the Delete key.
- Change Point Type: Right-click on a mask point to change its type (e.g., Bezier, Corner, or Auto Bezier). This can affect how the handles behave.
Scaling and Rotating the Entire Mask
- Select the Layer and Mask: Same as steps 1 and 2 above.
- Activate Transform Controls: Make sure the Selection tool (V) is active. You should see a bounding box around the mask.
- Scale: Hover your cursor near a corner of the bounding box. When you see the resize cursor (a double-headed arrow), click and drag to scale the mask.
- Proportional Scaling: Hold down the Shift key while dragging to scale proportionally, maintaining the mask's aspect ratio.
- Rotate: Move your cursor slightly further away from a corner of the bounding box. When you see the rotate cursor (a curved arrow), click and drag to rotate the mask.
Mask Feathering and Expansion
Besides reshaping the path, you can adjust feathering and expansion:
- Locate Mask Properties: In the Timeline panel, expand the layer properties, then expand "Masks," and select the specific mask you want to edit.
- Adjust Values:
- Mask Feather: Changes the softness of the mask edge. Increase the value for a softer edge.
- Mask Expansion: Expands or contracts the mask area. A positive value expands the mask, while a negative value contracts it.
Important Considerations
- Mask Mode: The mask mode (Add, Subtract, Intersect, etc.) influences how the mask interacts with the layer and other masks. Be sure the mask mode is set correctly for your intended result.
- Animation: You can animate any of these mask properties (path, feather, expansion, etc.) over time to create dynamic effects. Set keyframes for each property to change the values over time.
