Dotted line on curve? I'm making a video, and I have two identical objects that start in the same place and then separate. I want to have a dotted line connecting them which appears only when the two objects start separating and continues to grow as the objects continue to separate. This takes out using the array modifier.
Make a curve, attach empties as hooks to each end of the curve, parent then those hooks/empties to the objects.
That way when the objects move apart the curve will follow and grow.



For the curve to have some thickness, make it 3d and add some bevel.



CYCLES rendering 

To create the dotted lines for the curve, use a checker texture to control the transparency on a material .