How to change variable in another script after colliding?

Questions & Answers
1

Hello guys!

I’m making my first unity game right now, and I’m stuck with changing variables after a collision.

So:

I have an object named pistol that has a script Shooting.cs where I have variable int ammo.

103314-1u.png

And then I have a cube that after colliding, ammo variable should change. The name of a script inside the cube is AmmoPack.cs

103315-2u.png

AmmoPack.cs code looks like that:

  using System.Collections;
    using System.Collections.Generic;
    using UnityEngine;
    
    public class AmmoPack : MonoBehaviour
    {
        private Shooting shooting;
        private Transform gun;
        void Start()
        {
            gun = transform.Find("Main Camera/FPSController/FirstPersonCharacter/pistol");
            shooting = gun.GetComponent<Shooting>();
        }
    
    
        void Update()
        {
    
        }
    
        void OnTriggerEnter(Collider other)
        {
            shooting.ammo = 0;
        }
    }

But it keeps giving me Object reference not set to an instance of an object exception.

What should I do?

3

Remove

     private Shooting shooting;
     private Transform gun;
     void Start()
     {
         gun = transform.Find("Main Camera/FPSController/FirstPersonCharacter/pistol");
         shooting = gun.GetComponent<Shooting>();
     }

and change

void OnTriggerEnter(Collider other)
     {
         shooting.ammo = 0;
     }

to

void OnTriggerEnter(Collider other) {
       Shooting shooting = other.gameObject.GetComponentInChildren<Shooting>();
       if(shooting != null){
             shooting.ammo = 0;
       }
}
2

As you said, this script AmmoPack is inside the Cube object.

But then you are using:

transform.Find();

which looks for transforms childs of the object where this script is placed. (In this case is looking for childs of Cube, and they don’t exist).

Maybe you should crate a TAG for the pistol like “Weapon” and use:

gun = GameObject.FindWithTag("Weapon");

Which looks for GameObjects in the scene with this Tag.

You can also use GameObject.FindGameObjectsWithTag (with an “s” that make an array of all objects in the scene with this tag)

If using the FindWithTag be sure there is always only 1 GameObject in the scene with the tag Weapon.