Unity - How to write a "Behaviour" or script for entire scene (in C#)? - c#-4.0

Question

I am starting to learn Unity.
As I understand, We can write scripts(behaviors) in the form of C# files and apply them to each objects on the scene.
But how to write a script for the entire scene? I know this is a obvious question - there has to be a script for the entire scene so that all my objects "behave" in a synchronized way and it's gotta be pretty basic, but preliminary Google searches has not borne much fruit.
Can someone give me a quick guide?

Answer 1

Taking your "boxes" example comment I would do the following:
Create an empty gameobject, let's call it BoxesController...
Attach below BoxesController.cs script to it
In the editor inspector reference all boxes
BoxesController.cs
public class BoxesController: MonoBehaviour
{
public Transform box1, box2, box3;
void Update() {
// change boxes position
}
}
Now imagine you will need to have > 30 boxes in current scene... You will have a lot of work to reference each box. So you could change your script if you add a Tag to all boxes. Let's say you create a new tag inside Unity Tag Manager called "Box" and give it to all boxes.
You now can change BoxesController.cs script to the above and you will not have to reference all boxes in the Editor Inspector because they will be searched and referenced inside Start method.
BoxesController.cs
public class BoxesController: MonoBehaviour
{
public GameObject[] boxes;
void Start()
{
boxes = GameObject.FindGameObjectsWithTag("Box");
}
void Update() {
// change boxes position
foreach (GameObject go in boxes)
{
//get box name
string box_name = go.Name;
// get box transform property
Transform t = go.transform;
}
}
}
Please note that GameObject.FindGameObjectsWithTag is a heavy operation and that's why I did it in the Start method and saved the result to reuse it in Update method calls.

Answer 2

what you can do is create an empty GameObject and add a script to it and use one of the techniques described in the link to get access to the 3 boxes you want to move.
http://docs.unity3d.com/412/Documentation/ScriptReference/index.Accessing_Other_Game_Objects.html
In this case you probably want to use "1. Through inspector assignable references." which just means create a public Transform variable in the script, save, then in the Inspector drag the box in the slot that appeared in the script-component
edit: for further reading i'd suggest googling the term "Game Manager" in combination with "Singelton" and "Unity" :)