alt textNullReferenceException: Object reference not set to an instance of an object Complete.GameManager+c__Iterator1.MoveNext () (at Assets/TANKS/_Completed-Assets/Scripts/Managers/GameManager.cs:105)][1]
A NullReferenceException occurs when Unity tries to access a variable that points to null. In other words, you’re trying to access something that doesn’t exist.
Since the error is pointing you to line 105, it must be that m_CameraControl is null.
To verify this, you can put this right above:
if (m_CameraControl == null) {
Debug.Log("m_CameraControl is null!");
}
If you get that message in the console, then my hunch was right.
Fixing this can be a bit tricky, as you’ll have to trace your code to see where you forgot to initialize m_CameraControl. I can’t do this without seeing the whole GameManager script, but I’ll give you some general troubleshooting steps that might help:
- Make sure all of your scripts are attached to their respective game objects.
- Make sure you’ve defined any public variables in the inspector that you need to.
- Make sure your method names are correct. ex- Unity will call
void Start()
, but notvoid start()
orprivate void Start()
. - Lastly, try to trace your code line by line. If you find yourself arriving at line 105 before you have defined m_CameraControl, go back and see where you forgot to initialize it.
Good luck!
@MattG54321
GameManager.cs
using System.Collections;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;
namespace Complete
{
public class GameManager : MonoBehaviour
{
public int m_NumRoundsToWin = 5; // The number of rounds a single player has to win to win the game.
public float m_StartDelay = 3f; // The delay between the start of RoundStarting and RoundPlaying phases.
public float m_EndDelay = 3f; // The delay between the end of RoundPlaying and RoundEnding phases.
public CameraControl m_CameraControl; // Reference to the CameraControl script for control during different phases.
public Text m_MessageText; // Reference to the overlay Text to display winning text, etc.
public GameObject m_TankPrefab; // Reference to the prefab the players will control.
public TankManager[] m_Tanks; // A collection of managers for enabling and disabling different aspects of the tanks.
private int m_RoundNumber; // Which round the game is currently on.
private WaitForSeconds m_StartWait; // Used to have a delay whilst the round starts.
private WaitForSeconds m_EndWait; // Used to have a delay whilst the round or game ends.
private TankManager m_RoundWinner; // Reference to the winner of the current round. Used to make an announcement of who won.
private TankManager m_GameWinner; // Reference to the winner of the game. Used to make an announcement of who won.
private void Start()
{
// Create the delays so they only have to be made once.
m_StartWait = new WaitForSeconds (m_StartDelay);
m_EndWait = new WaitForSeconds (m_EndDelay);
SpawnAllTanks();
SetCameraTargets();
// Once the tanks have been created and the camera is using them as targets, start the game.
StartCoroutine (GameLoop ());
}
private void SpawnAllTanks()
{
// For all the tanks...
for (int i = 0; i < m_Tanks.Length; i++)
{
// ... create them, set their player number and references needed for control.
m_Tanks*.m_Instance =*
Instantiate(m_TankPrefab, m_Tanks.m_SpawnPoint.position, m_Tanks*.m_SpawnPoint.rotation) as GameObject;
m_Tanks.m_PlayerNumber = i + 1;
m_Tanks.Setup();
_}
}
private void SetCameraTargets()
{
// Create a collection of transforms the same size as the number of tanks.
Transform[] targets = new Transform[m_Tanks.Length];
// For each of these transforms…
for (int i = 0; i < targets.Length; i++)
{
// … set it to the appropriate tank transform._
targets = m_Tanks.m_Instance.transform;
_}
// These are the targets the camera should follow._
// m_CameraControl.m_Targets = targets;
_}
// This is called from start and will run each phase of the game one after another.
private IEnumerator GameLoop ()
{
// Start off by running the ‘RoundStarting’ coroutine but don’t return until it’s finished.
yield return StartCoroutine (RoundStarting ());
// Once the ‘RoundStarting’ coroutine is finished, run the ‘RoundPlaying’ coroutine but don’t return until it’s finished.
yield return StartCoroutine (RoundPlaying());
// Once execution has returned here, run the ‘RoundEnding’ coroutine, again don’t return until it’s finished.
yield return StartCoroutine (RoundEnding());
// This code is not run until ‘RoundEnding’ has finished. At which point, check if a game winner has been found.
if (m_GameWinner != null)
{
// If there is a game winner, restart the level.
SceneManager.LoadScene (0);
}
else
{
// If there isn’t a winner yet, restart this coroutine so the loop continues.
// Note that this coroutine doesn’t yield. This means that the current version of the GameLoop will end.
StartCoroutine (GameLoop ());
}
}
private IEnumerator RoundStarting ()
{
// As soon as the round starts reset the tanks and make sure they can’t move.
ResetAllTanks ();
DisableTankControl ();
// Snap the camera’s zoom and position to something appropriate for the reset tanks.
m_CameraControl.SetStartPositionAndSize ();
// Increment the round number and display text showing the players what round it is.
m_RoundNumber++;
m_MessageText.text = "ROUND " + m_RoundNumber;
// Wait for the specified length of time until yielding control back to the game loop.
yield return m_StartWait;
}
private IEnumerator RoundPlaying ()
{
// As soon as the round begins playing let the players control the tanks.
EnableTankControl ();
// Clear the text from the screen.
m_MessageText.text = string.Empty;
// While there is not one tank left…
while (!OneTankLeft())
{
// … return on the next frame.
yield return null;
}
}
private IEnumerator RoundEnding ()
{
// Stop tanks from moving.
DisableTankControl ();
// Clear the winner from the previous round.
m_RoundWinner = null;
// See if there is a winner now the round is over.
m_RoundWinner = GetRoundWinner ();
// If there is a winner, increment their score.
if (m_RoundWinner != null)
m_RoundWinner.m_Wins++;
// Now the winner’s score has been incremented, see if someone has one the game.
m_GameWinner = GetGameWinner ();
// Get a message based on the scores and whether or not there is a game winner and display it.
string message = EndMessage ();
m_MessageText.text = message;
// Wait for the specified length of time until yielding control back to the game loop.
yield return m_EndWait;
}
// This is used to check if there is one or fewer tanks remaining and thus the round should end.
private bool OneTankLeft()
{
// Start the count of tanks left at zero.
int numTanksLeft = 0;
// Go through all the tanks…
for (int i = 0; i < m_Tanks.Length; i++)
{
// … and if they are active, increment the counter._
if (m_Tanks.m_Instance.activeSelf)
numTanksLeft++;
_}
// If there are one or fewer tanks remaining return true, otherwise return false.
return numTanksLeft <= 1;
}*_
// This function is to find out if there is a winner of the round.
// This function is called with the assumption that 1 or fewer tanks are currently active.
private TankManager GetRoundWinner()
{
// Go through all the tanks…
for (int i = 0; i < m_Tanks.Length; i++)
{
// … and if one of them is active, it is the winner so return it.
if (m_Tanks*.m_Instance.activeSelf)
return m_Tanks;
_}
// If none of the tanks are active it is a draw so return null.
return null;
}
// This function is to find out if there is a winner of the game.
private TankManager GetGameWinner()
{
// Go through all the tanks…
for (int i = 0; i < m_Tanks.Length; i++)
{
// … and if one of them has enough rounds to win the game, return it._
if (m_Tanks.m_Wins == m_NumRoundsToWin)
return m_Tanks;
_}
// If no tanks have enough rounds to win, return null.
return null;
}
// Returns a string message to display at the end of each round.
private string EndMessage()
{
// By default when a round ends there are no winners so the default end message is a draw.
string message = “DRAW!”;
// If there is a winner then change the message to reflect that.
if (m_RoundWinner != null)
message = m_RoundWinner.m_ColoredPlayerText + " WINS THE ROUND!";
// Add some line breaks after the initial message.*
*message += "
";
// Go through all the tanks and add each of their scores to the message.
for (int i = 0; i < m_Tanks.Length; i++)
{_
message += m_Tanks.m_ColoredPlayerText + ": " + m_Tanks.m_Wins + " WINS
";
_}
// If there is a game winner, change the entire message to reflect that.
if (m_GameWinner != null)
message = m_GameWinner.m_ColoredPlayerText + " WINS THE GAME!";
return message;
}
// This function is used to turn all the tanks back on and reset their positions and properties.
private void ResetAllTanks()
{
for (int i = 0; i < m_Tanks.Length; i++)
{_
m_Tanks.Reset();
_}
}
private void EnableTankControl()
{
for (int i = 0; i < m_Tanks.Length; i++)
{_
m_Tanks.EnableControl();
_}
}
private void DisableTankControl()
{
for (int i = 0; i < m_Tanks.Length; i++)
{_
m_Tanks.DisableControl();
_}
}
}
}*_