Animating a paint stroke in the Timeline window

You can animate a paint stroke by setting keyframes for paint stroke properties. After Effects animates paint strokes automatically when you choose Write On from the Duration pop-up menu in the Paint palette or when you replace paint strokes (referred to as stroke targeting) in the Timeline window. The time you take to apply the stroke determines the stroke's duration; the speed of your movements determines velocity.

To animate a paint stroke automatically with Write On:

1. Open a layer and select a paint tool in the Tools palette.
2. In the Paint palette, choose Write On from the Duration pop-up menu.
3. Apply a paint stroke to the layer. As you paint, your movements are recorded in real time and determine the duration and velocity of the resulting stroke.
4. In the Timeline window, open the layer to view the paint stroke in the Stroke Options section. Two keyframes appear in the End parameter.
5. Drag the second keyframe to the frame where you want the complete stroke to appear. The stroke begins on the frame indicated by the first keyframe.

You can reverse the order of the animation by cutting and pasting the first keyframe in the Timeline window to a later time than the ending keyframe.

To animate a paint stroke by using stroke targeting:

1. Open a layer and select a paint tool in the Tools palette.
2. In the Paint palette, choose Single Frame, Constant, or Custom from the Duration pop-up menu.
3. In the Layer window, drag in the layer to create a paint stroke.
4. In the Timeline window, click the triangles next to the layer in the Strokes section and in the Paint section to view the brush stroke.
5. Do one of the following:
• Click the stopwatch for Shape to create a keyframe.
• Click the stopwatch for any other Brush properties that you want to animate.
6. Drag the current-time indicator to a new location in the Timeline window.
7. While the brush stroke is still selected, drag in the layer to create a new paint stroke. A second keyframe appears in the Timeline window for each animated property.

When you render the work area, After Effects interpolates brush shape and other animated properties for all frames between the two keyframes.


After Effects interpolates a brush shape (center) between two different strokes created with the same brush.