If you want to create an arrow that moves along a path on After Effects, especially a curved path, Trim Paths is useful.
First, create a shape layer path. This is the path the arrow will travel. With the path defined, select Shape 1 in the “Contents” property of the shape layer. Then, select the Add button and choose Trim Paths. Shape 1 can be the pointed part of the arrow, so give it a fitting name like “Arrow Head.” Then, duplicate “Arrow Head” and rename it something like “Arrow Tail,” and this will be the back part of the arrow.
For the Arrow Head Trim Paths property, link the End value to the Start value by using the pickwhip. Then, link both the Arrow Tail Trim Paths Start and End value to the Arrow Head Trim Paths Start value.
Now, define the Arrow Head shape. Go to the expression for the Trim Paths End value and append the plus sign and a number to the end of the expression. The number value dictates the length of the Arrow Head. To further shape the Arrow Head, go to the Stroke property and adjust the stroke width as needed. Under the Taper property, adjust either the start or end length (depending on the direction your arrow is going) to 100% to create the triangle shape. In this example, the arrow is moving toward the right.
Drag the Trim Paths start value up to see the Arrow Head move along the curves of the path.
Next, it’s time to shape the tail. On the Arrow Tail Trim Paths End property expression, append a minus sign and a numeric value to the end. This defines the Arrow Tail length. You may see a small gap where the arrow’s head and tail meet. If so, adjust the tail’s Trim Paths start property expression by adding one to close the gap. You can adjust other Taper properties to shape the tail accordingly.
Finally, go back to the Arrow Head Trim Paths Start property and set keyframes for the beginning and ending arrow motion along the path. Now, the arrow moves along the curved path.
Watch a short After Effects tutorial here:
