The timer starts after a collision with an object

Hello all!

I have a Timer script (C#):

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class Timer : MonoBehaviour {

    public Text counterText;
    public bool TimerOn;

    public float seconds, minutes;

    void Start(){
        TimerOn = false;
        Text counterText = GetComponent<Text>();
        counterText = GetComponent<Text>() as Text;
    }

    void Update(){
        if (TimerOn = true){
            minutes = (int)(Time.time / 60f);
            seconds = (int)(Time.time % 60f);
            counterText.text = minutes.ToString("00") + ":" + seconds.ToString("00");
        }
    }
}

And I want to do when my car will collide with the invisible object, for example, (Box1) is a timer starts running but if a collision with an object (Box2) is the timer will stop working.

Someone would like to help me?
It was not until I begin programming with Unity so please bear with us.
*
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*I am using google translator because I come from Polish, and I do not speak much English. :slight_smile:

You should look up the API for OnTriggerEnter and CompareTag

void OnTriggerEnter (Collider other) {
     if (other.gameObject.CompareTag("Box1")) {
          TimerOn = true;
     } else if (other.gameObject.CompareTag("Box2")) {
          TimerOn = false;
     }
}

Create a tag called “Box1” and “Box2” and put it on the two GameObjects that you want to collide with (make sure they have colliders as well)