SOLVED How to make a dynamic length animated dotted line?

I know there MUST be an example somewhere on these forums, but I can't find anything on this topic.

I'm trying to do this:

here's my version:

dropbox.com/s/mpgm3yx44ksl74t/AnimLineTest.c3p

getting close... just have to figure out how to animate the frames.

using the dist and angle and looping on dist, then using cos and sin to determine the x/y

EDIT: also I think it needs spaces in between the dots (drawing the line manually) - not sure this is the best way to do this....??

here's my final version. but I like newt's better since there's less stuff to do, and less objects.

but overall it was easier than I thought.