Hello all, I am using the most current version of Unity3d (5.4.1) and I am following the Space Shooter tutorial. I am at the point of adding points to the game when the player destroys the asteroids, part 3 section 2 “Counting points and ending the game”. However, when all the code is written, and I go to test, when the player shoots, the bolts go through the asteroids, and asteroids go through the player. Collision must be happening because the explosions still happen when the bolt hits the asteroid, and when the asteroid hits the player. During testing I get the error “NullReferenceException: Object reference not set to an instance of an object” in my DestroyByContact script. I have identified the culprit code piece, however I am at a loss as to how to fix it. When I comment out the code piece in the DestroyByContact script ‘gameController.Addscore(scoreValue)’
everything works fine, except for adding the score.
Please let me know if you would like me to post my scripts. Much thanks in advance!
@gjf thanks for the quick reply. i followed the tutorial step by step again just to be sure my code is in line. However i am still getting the same error and in game results. So first here is my error code
Severity Code Description Project File Line Suppression State
Error NullReferenceException: Object reference not set to an instance of an object Solution 'Space Shooter' (1 project) Assets/Scripts/DestroyByContact.cs 35
Here is the DestroyByContact code
using UnityEngine;
using System.Collections;
public class DestroyByContact : MonoBehaviour
{
public GameObject explosion;
public GameObject playerExplosion;
public int scoreValue;
private GameController gameController;
void start ()
{
GameObject gameControllerObject = GameObject.FindWithTag("GameController");
if (gameControllerObject != null)
{
gameController = gameControllerObject.GetComponent<GameController>();
}
if (gameController == null)
{
Debug.Log("Cannot find 'GameController' script");
}
}
void OnTriggerEnter(Collider other){
if (other.tag == "Boundary")
{
return;
}
Instantiate(explosion, transform.position, transform.rotation);
if (other.tag =="Player")
{
Instantiate(playerExplosion, other.transform.position, other.transform.rotation);
}
//gameController.AddScore(scoreValue);
gameController.AddScore(scoreValue);
Destroy(other.gameObject);
Destroy(gameObject);
}
}
And here is my GameController script just in case
using UnityEngine;
using System.Collections;
public class GameController : MonoBehaviour
{
public GameObject hazard;
public Vector3 spawnValues;
public int hazardCount;
public float spawnWait;
public float startWait;
public float waveWait;
public GUIText scoreText;
private int score;
void Start()
{
score = 0;
UpdateScore();
StartCoroutine(SpawnWaves ());
}
IEnumerator SpawnWaves()
{
while (true)
{
yield return new WaitForSeconds(startWait);
for (int i = 0; i < hazardCount; i++)
{
Vector3 spawnPosition = new Vector3(Random.Range(-spawnValues.x, spawnValues.x), spawnValues.y, spawnValues.z);
Quaternion spawnRotation = Quaternion.identity;
Instantiate(hazard, spawnPosition, spawnRotation);
yield return new WaitForSeconds(spawnWait);
}
yield return new WaitForSeconds (waveWait);
}
}
public void AddScore (int newScoreValue)
{
score += newScoreValue;
UpdateScore();
}
void UpdateScore ()
{
scoreText.text = "Score: " + score;
}
}
Any suggestions are greatly appreciated!
sorry if my code isnt properly formatted, still new to this community and unity itself 
- Do you have a GameController GameObject in your scene?
- Do you have tagged it correctly?
- Is the script GameController attached to it?
- Is the GameController GameObject active?
- Does the debug line fires at start?
- Did you dragged in the text field into your GameController?
Edit: Your Score Text variable is wrong! Except you really use GUIText and not Text in the Canvas System.
In the GameController make use of the namespace:
using UnityEngine.UI;
and instead of:
public GUIText scoreText;
use
public Text scoreText;
And test again.
You may also want to make the make a new function for game controller: see the codes below for “DestroyByContact”:
public GameObject explotion;
private GameObject newProjectile;
public GameObject playerExplotion;
public int scorePoints;
void gameController_Main()
{
GameController gameController = new GameController();
gameController = GameObject.FindObjectOfType<GameController>();
GameObject gameControllerObject = GameObject.FindWithTag("GameController");
if (gameController != null)
{
gameController = gameControllerObject.GetComponent<GameController>();
}
if (gameController == null)
{
Debug.Log("Cannot Find 'GameController' script");
}
gameController.AddScore(scorePoints);
}
********************************************************************************************************************
//And declare it on void OnTriggerEnter(Collider other)
*********************************************************************************************************************
void OnTriggerEnter(Collider other)
{
if (other.tag == "Boundary")
{
return;
}
newProjectile = Instantiate (explotion, transform.position, transform.rotation) as GameObject;
if (other.tag == "Player")
{
newProjectile = Instantiate(playerExplotion, other.transform.position, other.transform.rotation) as GameObject;
}
gameController_Main(); //this the declaration of the function gameController_Main
Destroy(other.gameObject);
Destroy(gameObject);
}
********************************************************************
for the code in "GameController" make that:
**********************************************************************
using UnityEngine;
using System.Collections;
using UnityEngine.UI;
public class GameController : MonoBehaviour {
public GameObject hazard;
public Vector3 SpawnValue;
public int hazardCount;
public float spawnWait;
public float startWait;
public float waveWait;
private GUIText scoreText; //make the GUIText as private
private int score;
void Start ()
{
GameObject scoreTextObject = GameObject.FindWithTag("ScoreText");
if (scoreTextObject != null)
{
scoreText = scoreTextObject.GetComponent<GUIText>();
}
if (scoreText == null)
{
Debug.Log("Cannot Find 'scoreText' Script");
}
score = 0;
UpdateScore();
StartCoroutine(SpawnWaves());
}
IEnumerator SpawnWaves ()
{
yield return new WaitForSeconds (startWait);
while (true)
{
for (int i = 0; i < hazardCount; i++)
{
Vector3 spawnPosition = new Vector3 (Random.Range (-SpawnValue.x, SpawnValue.x), 0.0f, SpawnValue.z);
Quaternion spawnRotation = Quaternion.identity;
Instantiate (hazard, spawnPosition, spawnRotation);
yield return new WaitForSeconds (spawnWait);
}
yield return new WaitForSeconds(waveWait);
}
}
public void AddScore(int newScoreValue)
{
score += newScoreValue;
UpdateScore();
}
void UpdateScore ()
{
scoreText.text = "Score: " + score;
}
}
Hope this will help.