Animate the points on a path or clipping path
In Microsoft Expression Blend, you can animate the points (or vertices) on a path object. For example, you could animate the points of a clipping path to gradually reveal the object underneath the clipping path. You could convert text in a TextBlock to path objects, and then animate the letters to change them into other shapes, perhaps even reversing the storyboard so that you start with shapes that change into letters.
Path objects are created by the Pen tool , by the Pencil tool , and by converting other objects (such as shapes or text) to paths.
If you do not have a path object on the artboard, you can create one by following the instructions in one of the following topics:
Open the storyboard to which you want to add the path animation timeline, or create a new storyboard.
In the Objects and Timeline panel, select the path object that you want to animate.
In the Tools panel, select the Direct Selection tool . The points of your path object are identified on the artboard by small squares.
Move the timeline playhead to the location on the timeline where you want to record a change in one of the points.
On the artboard, either drag or hold down ALT while dragging individual points and line segments to new locations. You can also select the Pen tool to add or remove points on the path.
If you add or remove points when in timeline-recording mode, the results take effect from the start of the timeline. For example, removing a point changes the starting shape of the path as if you had removed the point when not in timeline-recording mode.
Continue moving the timeline playhead and modifying points until you complete your animation.