我创建了4个C＃脚本。当我运行2D统一游戏时，我在控制台中看到此警告。
“ Assets \ Scripts \ GameHandler.cs（7,34）：警告CS0649：从未将字段'GameHandler.car'分配给该字段，并且其默认值始终为null”
我正在统一2d中使用c＃脚本创建类似于蛇的游戏。从未使用过unity或C＃，这是我的第一个项目。到目前为止一切顺利，但是，我一直收到此警告，这导致我的游戏崩溃。我已经在脚本中附加了2个脚本，第一个游戏处理器是该问题所在的位置，我认为它是指Car我下面附加的类。很多代码，所以我很抱歉，我只是一头雾水。
public class GameHandler : MonoBehaviour
{
[SerializeField] private Car car;
private LevelGrid levelGrid;
// Start is called before the first frame update
private void Start()
{
Debug.Log("GameHandler.Start");
//GameObject carHeadGameObject = new GameObject();
//SpriteRenderer carSpriteRenderer = carHeadGameObject.AddComponent<SpriteRenderer>();
//carSpriteRenderer.sprite = GameAssets.instance.carHeadSprite;
levelGrid = new LevelGrid(20,20); //width,height of grid
car.Setup(levelGrid);
levelGrid.Setup(car);
}
}
--------------------------------------
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Car : MonoBehaviour
{
private enum Direction
{
Left,
Right,
Up,
Down
}
private enum State
{
Alive,
Dead
}
private State state;
private Vector2Int gridPosition; //uses ints instead of floats useful for grid positiioning
private float gridMoveTimer; //time remaining until next movement
private float gridMoveTimerMax; // time between moves
private Direction gridMoveDirection;
private LevelGrid levelGrid;
private int carsize;
private List<CarMovePosition> carMovePositionList;
private List<Carsize> carSizeList;
public void Setup(LevelGrid levelGrid) {
this.levelGrid = levelGrid;
}
private void Awake() {
gridPosition = new Vector2Int(10,10); //initalise grid position into middle of grid
gridMoveTimerMax = .2f; //car to move along grid every 1/2 second
gridMoveTimer = gridMoveTimerMax; //0f
gridMoveDirection = Direction.Right; // default move right
carMovePositionList = new List<CarMovePosition>();
carsize = 0;
carSizeList = new List<Carsize>();
state = State.Alive;
}
private void Update()
{
switch (state)
{
case State.Alive:
HandleInput(); // checks for keyboard input
HandleGridMovement();
break;
case State.Dead:
break;
}
}
private void HandleInput()
{
if (Input.GetKeyDown(KeyCode.UpArrow))
{
if (gridMoveDirection != Direction.Down)
{ // can only go up if not going down
gridMoveDirection = Direction.Up;
}
}
//return true on up arrow press
if (Input.GetKeyDown(KeyCode.DownArrow))
{
if (gridMoveDirection != Direction.Up)
{
gridMoveDirection = Direction.Down;
}
}
if (Input.GetKeyDown(KeyCode.LeftArrow))
{
if (gridMoveDirection != Direction.Right)
{
gridMoveDirection = Direction.Left;
}
}
if (Input.GetKeyDown(KeyCode.RightArrow))
{
if (gridMoveDirection != Direction.Left)
{
gridMoveDirection = Direction.Right;
}
}
}
private void HandleGridMovement()
{
gridMoveTimer += Time.deltaTime; // amount of time left since last update
if (gridMoveTimer >= gridMoveTimerMax)//if true then 1 sec since last move
{
gridMoveTimer -= gridMoveTimerMax;
CarMovePosition previousCarMovePosition = null;
if (carMovePositionList.Count > 0){
previousCarMovePosition = carMovePositionList[0];
}
CarMovePosition carMovePosition = new CarMovePosition(previousCarMovePosition, gridPosition, gridMoveDirection);
carMovePositionList.Insert(0, carMovePosition);
Vector2Int gridMoveDirectionVector;
switch (gridMoveDirection) {
default:
case Direction.Right: gridMoveDirectionVector = new Vector2Int(+1, 0);break;
case Direction.Left: gridMoveDirectionVector = new Vector2Int(-1, 0); break;
case Direction.Up: gridMoveDirectionVector = new Vector2Int(0, +1); break;
case Direction.Down: gridMoveDirectionVector = new Vector2Int(0, -1); break;
}
gridPosition += gridMoveDirectionVector;
bool cargotfuel = levelGrid.Trycarfuel(gridPosition);
if (cargotfuel)
{
carsize++;
CreateCarSize();
}
if (carMovePositionList.Count >= carsize + 1)
{
carMovePositionList.RemoveAt(carMovePositionList.Count - 1);
}
foreach (Carsize carsize in carSizeList)
{
Vector2Int carSizeGridPosition = carsize.GetGridPosition();
if (gridPosition == carSizeGridPosition)
{
//print("Gameover");
state = State.Dead;
}
}
transform.position = new Vector3(gridPosition.x, gridPosition.y);
//move transform based on location of gridPosition
transform.eulerAngles = new Vector3(0, 0, GetAngleFromVector(gridMoveDirectionVector) - 90);
//modify transform to face the correct way
UpdateCarSize();
}
}
private void CreateCarSize()
{
carSizeList.Add(new Carsize(carSizeList.Count));
}
private void UpdateCarSize(){
for (int i = 0; i < carSizeList.Count; i++) {
carSizeList[i].SetCarMovePosition(carMovePositionList[i]);
//carSizeList[i].SetGridPosition(carMovePositionList[i].GetGridPosition());
}
}
private float GetAngleFromVector(Vector2Int dir)
{
float n = Mathf.Atan2(dir.y, dir.x) * Mathf.Rad2Deg;
if (n < 0) n += 360;
return n;
}
public Vector2Int GetGridPosition()
{
return gridPosition;
}
//returns car list of positions full with body
public List<Vector2Int> Getcargridpositionlist(){
List<Vector2Int> gridPositionList = new List<Vector2Int>() { gridPosition };
foreach (CarMovePosition carMovePosition in carMovePositionList)
{
gridPositionList.Add(carMovePosition.GetGridPosition());
}
return gridPositionList;
}
private class Carsize{
private CarMovePosition carMovePosition;
private Transform transform;
public Carsize(int sizeIndex){
GameObject carsGameObject = new GameObject("carBody", typeof(SpriteRenderer));
carsGameObject.GetComponent<SpriteRenderer>().sprite = GameAssets.instance.carsSprite;
carsGameObject.GetComponent<SpriteRenderer>().sortingOrder = -sizeIndex;
transform = carsGameObject.transform;
}
public void SetCarMovePosition(CarMovePosition carMovePosition){
this.carMovePosition = carMovePosition;
transform.position = new Vector3(carMovePosition.GetGridPosition().x, carMovePosition.GetGridPosition().y);
float angle;
switch (carMovePosition.GetDirection()){
default:
case Direction.Up:// going up
switch (carMovePosition.GetPreviousDirection()){
default:
angle = 0; break;
case Direction.Left: // was going left
angle = 0 + 45; break;
case Direction.Right:// was going right
angle = 0 - 45; break;
}
break;
case Direction.Down:
switch (carMovePosition.GetPreviousDirection()){
default:
angle = 180; break;
case Direction.Left:
angle = 180 + 45; break;
case Direction.Right:
angle = 180 - 45; break;
}
break;
case Direction.Left:
switch (carMovePosition.GetPreviousDirection()){
default:
angle = -90; break;
case Direction.Down:
angle = -45; break;
case Direction.Up:
angle = 45; break;
}
break;
case Direction.Right: // going right
switch (carMovePosition.GetPreviousDirection()){
default:
angle = 90; break;
case Direction.Down: // previously going down
angle = 45; break;
}
break;
}
transform.eulerAngles = new Vector3(0, 0, angle);
}
public Vector2Int GetGridPosition()
{
return carMovePosition.GetGridPosition();
}
}
private class CarMovePosition{
private CarMovePosition previousCarMovePosition;
private Vector2Int gridPosition;
private Direction direction;
public CarMovePosition(CarMovePosition previousCarMovePosition, Vector2Int gridPosition, Direction direction){
this.previousCarMovePosition = previousCarMovePosition;
this.gridPosition = gridPosition;
this.direction = direction;
}
public Vector2Int GetGridPosition(){
return gridPosition;
}
public Direction GetDirection(){
return direction;
}
public Direction GetPreviousDirection(){
if (previousCarMovePosition == null){
return Direction.Right;
} else {
return previousCarMovePosition.direction;
}
}
}
}
可能是我以前必须在unity2d本身中单击/拖动某些内容的情况。但是我现在迷失了。
发生警告是因为您没有初始化对象“ car”，并且当它尝试使用未分配任何值的对象时，游戏会崩溃。
您必须在使用任何对象之前对其进行初始化，以避免崩溃。
因此，您的Start（）方法必须像这样：
private void Start()
{
Debug.Log("GameHandler.Start");
car = new Car(); // you must initialize objects before using them!
//GameObject carHeadGameObject = new GameObject();
//SpriteRenderer carSpriteRenderer = carHeadGameObject.AddComponent<SpriteRenderer>();
//carSpriteRenderer.sprite = GameAssets.instance.carHeadSprite;
levelGrid = new LevelGrid(20,20); //width,height of grid
car.Setup(levelGrid);
levelGrid.Setup(car);
}
希望对您有所帮助！
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