Hi Terry - I don't think this IS 3D though. Check out the code he posted. There's no Z going on.
Whatever though - what I'm getting at is there's no reason (that I can see at least) why the lines SUDDENLY change length dramatically. Check out the pic I posted again, There's NO detail there that would require it. Maybe I'm wrong - just thinking.
Anyway - as we've both now said - it's working so it doesn't really matter.