What is the best method to control the movement of a group of objects based on the collision trigger of any individual?

Questions & Answers
1

I’m not sure what the best approach to this is, but I have searched around a lot for some solution but nothing I try seems to work.

I want to have a group of four cubes fall down (tetris style), and when one of them hits the ground, or a previously grounded cube, for all members of the group to stop falling and snap to a grid. The reason I don’t want to set the arrangement to be a single object is that they are being shot at and destroyed on their way down.

At the moment I have a empty prefab “shape” with the four “cubes” in it. The shape script just sets the initial position of the group and nothing else. The cube script is below. I’ve tried a lot to set some sort of groupFalling variable in the shape, but I cannot for the life of me work out how to get a cube to access and change it. Nor am I sure that is the best approach.

My current cube script looks like this (just in case it helps):

using UnityEngine;
using System.Collections;

public class Cube : MonoBehaviour {
	private Transform myTransform;
	private float cubeSpeed = 5;
	public bool falling;
	
	// Use this for initialization
	void Start () {
		myTransform = transform;
		falling = true;
	}
	
	// Update is called once per frame
	void Update () {
		if (falling) {
			myTransform.Translate(Vector3.down * cubeSpeed * Time.deltaTime);
		}
	}
		
	void OnTriggerEnter(Collider collider) {
		if (collider.gameObject.CompareTag("Bullet") && falling) {
			DestroyObject(this.gameObject);
			DestroyObject(collider.gameObject);
		}
		if (collider.gameObject.CompareTag("Floor")) {
			falling = false;
			transform.gameObject.tag = "Floor";
		}
	}
}
2

Give all your cubes a “Cube” tag and when one hits the floor, do something like this:

        public GameObject [] cubes;
        void OnTriggerEnter(Collider collider) {
            if (collider.gameobject.tag == "Floor")
    {
                cubes = GameObject.FindGameObjectsWithTag("Cubes");
            
            foreach (GameObject cube in cubes)
    {
             cube.tag = "Floor";
            }
          }
        }

And above where you translate when falling is true, you could do something like this:

if (gameObject.tag != "Floor") {
         myTransform.Translate(Vector3.down * cubeSpeed * Time.deltaTime);
       }

In this case you won’t need your falling boolean variable.