StateMachine 空引用

Question

我正在做 tps 的一些原型，但我遇到了错误

NullReferenceException: Object reference not set to an instance of an object
IdleState.EnterState () (at Assets/Scripts/Character/Player/MovementState/States/Grounded/States/IdleState.cs:10)
StateMachine.ChangeState (PlayerBase newState) (at Assets/Scripts/StateMachine/StateMachine.cs:9)
Player.Start () (at Assets/Scripts/Character/Player/Player.cs:27)

&

NullReferenceException: Object reference not set to an instance of an object
PlayerMovementState.GetMovementSpeed () (at Assets/Scripts/Character/Player/MovementState/States/PlayerMovementState.cs:52)
PlayerMovementState.Move () (at Assets/Scripts/Character/Player/MovementState/States/PlayerMovementState.cs:37)
PlayerMovementState.UpdateState () (at Assets/Scripts/Character/Player/MovementState/States/PlayerMovementState.cs:24)
IdleState.UpdateState () (at Assets/Scripts/Character/Player/MovementState/States/Grounded/States/IdleState.cs:15)
StateMachine.UpdateState () (at Assets/Scripts/StateMachine/StateMachine.cs:14)
Player.Update () (at Assets/Scripts/Character/Player/Player.cs:33) 

有文件代码

public abstract class PlayerBase 
{
    public abstract void EnterState();
    public abstract void UpdateState();
    public abstract void ExitState();
    public abstract void HandleInput();
}

public abstract class StateMachine 
{
    protected PlayerBase _currentState;

    public void ChangeState(PlayerBase newState)
    {
        _currentState?.ExitState();
        _currentState = newState;
        _currentState.EnterState();
    }

    public void UpdateState()
    {
        _currentState?.UpdateState();
    }

    public void ExitState()
    {
        _currentState?.ExitState();
    }

    public void HandleInput()
    {
        _currentState?.HandleInput();
    }
}

using UnityEngine;

public class PlayerMovementState : PlayerBase
{
    protected PlayerMovementStateMachine _stateMachine;
    protected PlayerGroundedData _movementData;

    public PlayerMovementState(PlayerMovementStateMachine stateMachine)
    {
    }


    #region Base Methods
    public override void EnterState()
    {
        Debug.Log("State " + GetType().Name);
    }
    public override void ExitState()
    {

    }
    public override void UpdateState()
    {
        Move();
    }
    public override void HandleInput()
    {
        ReadMovementInput();
    }

    #endregion

    #region Main Methods

    private void Move()
    {
        float movementSpeed = GetMovementSpeed();
        Vector2 direction = MovementDirection();

        _stateMachine.Player.Controller.Move(direction * movementSpeed * Time.deltaTime);
    }

    private Vector2 ReadMovementInput()
    {
        _stateMachine.ReusableData.Movement = _stateMachine.Player.Input.PlayerAction.Movement.ReadValue<Vector2>();

        return _stateMachine.ReusableData.Movement;
    }

    private float GetMovementSpeed()
    {
        return _movementData.BaseSpeed * _stateMachine.ReusableData.MovementSpeedModifier;
    }


    #endregion

    #region Reusable Methods

    private Vector2 MovementDirection()
    {
        return new Vector2(_stateMachine.ReusableData.Movement.x, _stateMachine.ReusableData.Movement.y);
    }

    #endregion
}

using UnityEngine;

public class Player : MonoBehaviour
{
    public CharacterController Controller;
    private PlayerMovementStateMachine _movementStateMachine;
    public PlayerInput Input { get; private set; }

    public Transform PlayerBody;

    public Transform GroundPosition;

    private void Awake()
    {
        Controller = GetComponent<CharacterController>();

        _movementStateMachine = new PlayerMovementStateMachine(this);

        PlayerBody = GameObject.FindGameObjectWithTag(Tags.PlayerBody).GetComponent<Transform>();
        GroundPosition = GameObject.FindGameObjectWithTag(Tags.GroundCheck).GetComponent<Transform>();
    }

    private void Start()
    {
        if(_movementStateMachine != null)
        {
        _movementStateMachine.ChangeState(_movementStateMachine.IdleState);
        }
    }

    private void Update()
    {
        _movementStateMachine.UpdateState();
        _movementStateMachine.HandleInput();
    }


}

public class IdleState : PlayerMovementState
{
    public IdleState(PlayerMovementStateMachine stateMachine) : base(stateMachine)
    {
    }

    public override void EnterState()
    {
        base.EnterState();
        _stateMachine.ReusableData.MovementSpeedModifier = 0;
    }

    public override void UpdateState()
    {
        base.UpdateState();
        if(_stateMachine.Player.Controller.velocity.magnitude > 0f)
        {
            _stateMachine.ChangeState(_stateMachine.RunState);
        }
    }

}

using UnityEngine;

public class PlayerStateReusableData 
{
    public Vector2 Movement { get; set; }
    public float MovementSpeedModifier { get; set; } = 1f;
}

我在 ytb 上搜索，询问了 chatgpt，但我仍然不明白缺少什么。 如果我能收到一些提示，我将不胜感激

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