Best way to tell if an object is within a region?

Unity Engine
1

I can think of lots of ways to do it… what’s the best?

I want my object’s scrip to know when it enters a space–as defined by an invisible cube or sphere, say.

Like collision detection without bouncing off…

2

I’d say use a trigger, and have a tiny script on the trigger with an OnTriggerEnter function, which just does a SendMessage to a collider that enters the trigger. Maybe pass the name of the trigger if you need specific info like that.

–Eric

3

That makes sense to me. It would be great to have a way for an object to know it had entered a trigger, without having to put a script on the trigger itself. Like checking the trigger’s name.?

I was just using a distance comparison, and that works fine (for spheres) but it’s not flexible and probably a bad habit! So I wanted to learn what I SHOULD be doing before I forgot to ask :slight_smile:

4

The object entering the trigger also gets the message. The only catch is that one of the two objects has to be a rigidbody for all of these trigger (and collision) messages.

http://unity3d.com/Documentation/ScriptReference/MonoBehaviour.OnTriggerEnter.html

-Jon

5

I’m guessing a distance comparison using Vector3.Distance is more efficient than using triggers as long as a spherical/circular boundary is all you need.

6

Since that takes, like, virtually no effort and has basically no effect on speed, I can’t imagine why. :wink: However, aarku is right, the object entering the trigger also gets the message, which I knew but totally forgot about… I would expect that scripting distance comparisons yourself is going to be slower than triggers, since those are done 100% natively and while user compiled code is relatively fast, it’s apparently 50% as fast as native code. But probably not enough difference to be noticeable.

–Eric

7

I just like having fewer scripts, and more in one script :slight_smile:

But now I have some good things to think about!

8

I totally understand that since I felt that way myself ;), but I’m starting to think it’s more of a bad habit in Unity than anything, and that it’s better to have a lot of little modular scripts than one colossal do-all script that becomes hard to maintain.

–Eric

9

You haven’t seen my Director work :lol:

10

If you don’t like the trigger approach for some reason, which has the smallest performance overhead btw.

You can use: Physics.OverlapSphere which gives you back a list of colliders.

11

Neat–I will keep that method in mind too!