Calling GetComponent<>() is detaching object at runtime

2D
1

I’m working through the Angry Meteor tutorial, and it’s all working except the game Resetter Script that is attached to the Boundary that surrounds the play area (BoxCollider2D).

I dragged my Asteroid object into the RigidBody2D box for the script reference and pressed play, but I kept getting NullReference errors in Resetter script, and I saw the object disappear from the script reference box. So when I commented out GetComponent<>(RigidBody2D) it didn’t disappear from the script ref. box. So I added a debug line on the GetComponent call, and it’s null at runtime and I can’t figure out why. I tried turning off all other scripts and verified the Asteroid has a RigidBody2D,and also verified that I set the script reference back to None, and dragged it on again. It just keeps detaching. Can anyone help me out?
Code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Resetter : MonoBehaviour {

    public Rigidbody2D asteroid;
    public float resetSpeed = 0.025f;

    private SpringJoint2D spring;
    private float resetSpeedSqr;

   
    void Start () {
        Debug.Log(GetComponent<Rigidbody2D>() == null);
        //asteroid = GetComponent<Rigidbody2D>();
        //spring = asteroid.GetComponent<SpringJoint2D>();
        //resetSpeedSqr = resetSpeed * resetSpeed;

    }

    /*
    void Update () {
        Debug.Log("Update");
        if (Input.GetKeyDown (KeyCode.R)) {
            Debug.Log("R Pressed.");
            Reset();
        }
        if(asteroid.velocity.sqrMagnitude < resetSpeedSqr && spring == null) {
            Reset();
        }
    }

    private void OnTriggerExit2D(Collider2D collision) {
        Rigidbody2D rb = collision.GetComponent<Rigidbody2D>();
        if (rb == asteroid) {
            Reset();
        }
    }

    void Reset() {
        Application.LoadLevel(Application.loadedLevel);
    }
    */
}
2

If the Rigidbody2D is supposed to be set via inspector, the line “asteroid = GetComponent” does not make sense, since it would overwrite whatever you assign to “asteroid” in edit-mode.

Have you tried simply removing that line and leaving everything else as they were?

1 Like
3

Yes, when I remove that line, it doesn’t disappear from the inspector.
But the script is attached to the “Boundary” objects, which takes a public RigidBody2D (the Asteroid).
Are you saying I don’t need a GetComponent to get a reference to the Asteroid?

4

mikael_juhala You were right.
I just took the GetComponent out and accessed asteroid. Thank you!!!

Working code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;

public class Resetter : MonoBehaviour {

    public Rigidbody2D asteroid;
    public float resetSpeed = 0.025f;

    private SpringJoint2D spring;
    private float resetSpeedSqr;

   
    void Start () {
        spring = asteroid.GetComponent<SpringJoint2D>();
        resetSpeedSqr = resetSpeed * resetSpeed;
    }
   
    void Update () {
       
        if (Input.GetKeyDown (KeyCode.R)) {
            Reset();
        }
      
        if(asteroid.velocity.sqrMagnitude < resetSpeedSqr && spring == null) {
            Reset();
        }
    
    }   

    private void OnTriggerExit2D(Collider2D collision) {       
        Reset();
    }
   
    void Reset() {
        SceneManager.LoadScene("Main");
    }
}