thats what i was meaning. you either do it for x or for y. not both in the same. thats how i used to do enemy zones and distance. its just not good, its horribly innacurate, unless youre really wanting a box zone area.
Ok, with the picture I understand what you mean now.
And you're right, the zone created by your method is more logical than mine. Except that I'm working on a platform game, and the square is good in that case (the enemy I'm working on precisely). But I'm curious to see a short exemple of your method cause I'm planning to have flying enemies, and in this case, your method will be better.
This subject would be a good subject for a tutorial I think...
EDIT : I asked an exemple because I don't know what mean ^ and sqrt in math... Sorry I'm 35 years old, school is far away from me !