I am following a Unity tutorial and faced this problem
NullReferenceException: Object reference not set to an instance of an object
PieceSpawner.Spawn () (at Assets/Script/PieceSpawner.cs:25)
Segment.Spawn () (at Assets/Script/Segment.cs:30)
LevelManager.SpawnSegment () (at Assets/Script/LevelManager.cs:94)
LevelManager.GenerateSegment () (at Assets/Script/LevelManager.cs:69)
LevelManager.Update () (at Assets/Script/LevelManager.cs:58)
and
NullReferenceException: Object reference not set to an instance of an object
Segment.Awake () (at Assets/Script/Segment.cs:22)
UnityEngine.Object:Instantiate(GameObject)
LevelManager:GetSegment(Int32, Boolean) (at Assets/Script/LevelManager.cs:121)
LevelManager:SpawnSegment() (at Assets/Script/LevelManager.cs:84)
LevelManager:GenerateSegment() (at Assets/Script/LevelManager.cs:69)
LevelManager:Update() (at Assets/Script/LevelManager.cs:58)
. This game is a subway surfers type of game that generates endless objects as you go on. Why is this error happening? Is it related to an unity object or the code? I think happened after updating to 2021.1.26f1. Here is the code, what should I change?
PieceSpawner.cs:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class PieceSpawner : MonoBehaviour {
public PieceType type;
private Piece currentPiece;
public void Spawn()
{
int amtObj = 0;
switch(type)
{
case PieceType.jump:
amtObj = LevelManager.Instance.jumps.Count;
break;
case PieceType.slide:
amtObj = LevelManager.Instance.slides.Count;
break;
case PieceType.longblock:
amtObj = LevelManager.Instance.longblocks.Count;
break;
case PieceType.ramp:
amtObj = LevelManager.Instance.ramps.Count;
break;
}
currentPiece = LevelManager.Instance.GetPiece (type, Random.Range(0, amtObj));
currentPiece.gameObject.SetActive (true);
currentPiece.transform.SetParent (transform, false);
}
public void Despawn()
{
currentPiece.gameObject.SetActive (false);
}
}
LevelManager.cs:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class LevelManager : MonoBehaviour {
public bool SHOW_COLLIDER = true; //$$
public static LevelManager Instance { set; get;}
// Level spawning
private const float DISTANCE_BEFORE_SPWAN = 100f;
private const int INITIAL_SEGMENT = 10;
private const int MAX_SEGMENT_ON_SCREEN = 15;
private Transform cameraContainer;
private int amountOfActiveSegment;
private int continiousSegments;
private int currentSpawnZ;
private int currentLevel;
private int y1, y2, y3;
// List of pieces
public List<Piece> ramps = new List<Piece>();
public List<Piece> longblocks = new List<Piece>();
public List<Piece> jumps = new List<Piece>();
public List<Piece> slides = new List<Piece>();
[HideInInspector]
public List<Piece> pieces = new List<Piece>(); // All pieces on the pool
// List of segments
public List<Segment> availableSegments = new List<Segment>();
public List<Segment> availableTransition = new List<Segment>();
[HideInInspector]
public List<Segment> segments = new List<Segment> ();
// Gameplay
private bool isMoving;
private void Awake()
{
cameraContainer = Camera.main.transform;
currentSpawnZ = 0;
currentLevel = 0;
}
private void Start()
{
for (int i = 0; i < INITIAL_SEGMENT; i++) {
GenerateSegment ();
}
}
private void Update()
{
if (currentSpawnZ - cameraContainer.position.z < DISTANCE_BEFORE_SPWAN)
{
GenerateSegment ();
}
if (amountOfActiveSegment >= MAX_SEGMENT_ON_SCREEN) {
segments [amountOfActiveSegment - 1].DeSpawn();
amountOfActiveSegment--;
}
}
private void GenerateSegment()
{
SpawnSegment ();
if (Random.Range (0f, 1f) < (continiousSegments * 0.25f)) {
SpawnTransition ();
continiousSegments = 0;
} else {
continiousSegments++;
}
}
private void SpawnSegment()
{
List<Segment> possibleSegments = availableSegments.FindAll (x => x.beginY1 == y1 || x.beginY2 == y2 || x.beginY3 == y3);
int id = Random.Range (0, possibleSegments.Count);
Segment s = GetSegment (id, false);
y1 = s.endY1;
y2 = s.endY2;
y3 = s.endY3;
s.transform.SetParent (transform);
s.transform.localPosition = Vector3.forward * currentSpawnZ;
currentSpawnZ += s.lenght;
amountOfActiveSegment++;
s.Spawn ();
}
private void SpawnTransition()
{
List<Segment> possibleTransition = availableTransition.FindAll (x => x.beginY1 == y1 || x.beginY2 == y2 || x.beginY3 == y3);
int id = Random.Range (0, possibleTransition.Count);
Segment s = GetSegment (id, true);
y1 = s.endY1;
y2 = s.endY2;
y3 = s.endY3;
s.transform.SetParent (transform);
s.transform.localPosition = Vector3.forward * currentSpawnZ;
currentSpawnZ += s.lenght;
amountOfActiveSegment++;
s.Spawn ();
}
public Segment GetSegment(int id, bool transition)
{
Segment s = null;
s = segments.Find (x => x.SegID == id && x.transition == transition && !x.gameObject.activeSelf);
if (s == null) {
GameObject go = Instantiate (transition ? availableTransition [id].gameObject : availableSegments [id].gameObject) as GameObject;
s = go.GetComponent<Segment> ();
s.SegID = id;
s.transition = transition;
segments.Insert (0, s);
} else {
segments.Remove (s);
segments.Insert (0, s);
}
return s;
}
public Piece GetPiece(PieceType pt, int visualIndex)
{
Piece p = pieces.Find(x => x.type == pt && x.visualIndex == visualIndex && !x.gameObject.activeSelf);
if (p == null) {
GameObject go = null;
switch (pt) {
case PieceType.ramp:
go = ramps [visualIndex].gameObject;
break;
case PieceType.longblock:
go = longblocks [visualIndex].gameObject;
break;
case PieceType.jump:
go = jumps [visualIndex].gameObject;
break;
case PieceType.slide:
go = slides [visualIndex].gameObject;
break;
}
go = Instantiate (go);
p = go.GetComponent<Piece> ();
pieces.Add (p);
}
return p;
}
}
