Hmm, yeah I see a couple of different problems there.

I was able to tune up one thing that helped reduce the bumps near the middle, but there is still some additional work to make it work better overall. I've added this to my list of stuff to fix up, but I probably won't get a chance to work more on it until some of the more basic stuff (array, units, background images, ...) is wrapped up.

You'll probably run into other problems like this, when you do please send me the file just like you did here. When I do work on this area more in depth, having examples like this really helps a lot.

- Michael