Here is attack area visualization widget. Currently its work only for cannons and direct fire towers. It's damned slow, so currently it can be used only to place towers. When you build tower, press meta key to see, where your tower can fire.
There are some ugly maths, may be you guys can help to improve that. Also may be to do something with square - made them more smooth.
Any help would be appreciate.
P.S.
This is continue of this topic