Use freestyle to animate a sketch being made?

I know you can use freestyle to make a drawing move around, but how would you animate a drawing being made? If anybody has seen The Pacific, I’m looking for the effect they did in the opening. If not, this is what I’m talking about: (Sorry I can’t embed it, youtube won’t let me)
Thanks for any help in advance!

Bumped because I updated the video- posted the wrong one at first.

Thanks for the help! I’ll be sure to post the video when I’m done.

Just animate a curve growing over time and apply a freestyle stroke to it.

However then NPR effect for a hand drawn line relies on length of a curve and terminators so you may end up with undesirable NPR animation during the curve draw.

I just tested it, it seems to work fine for me. I am animating the END BEVEL FACTOR which should not internally change the length of the curve, only it’s displayed render. But do you have a Line Set in mind that the technique does not work with? I just tried the default line set with a texture applied.

yes I guess it may depend on line set having effects applied to it. I would guess that you might add some 2D distortion for the hand drawn effect (like a displacement) but I’m happy to be wrong.

I did something like this. I used grease pencil, converted it to a curve, and added a build modifier to the curve. End result:

Really simple approach good result. Would be cool to see this taken further with some compositing effects.