How to make a moving arrow? I want to create an animation where a arrow points from the red circle to the blue circle.

My standard approch would be, to start with a cube on frame 1, deform the cube to a rectangle in frame 2, than to a long line and eventually in frame 4 I have the full arrow.

Now in this approach two things are not optimal:


The arrow looks really bad.
Its hard work to do this.


Is there a shorter approach to get a more accurate looking arrow which is developing during time? I know the curve->path object, but I dont know how to explain to blender that it should develop during time (as in the image below).
One solution is to make your arrow as a Curve, and then adding a Build Modifier to it.



It will animate along the direction of the curve (represented by the arrows in Edit mode), but you can check Reverse to change this. Also you can cange the start and length fields to your likes.