Unity网球游戏项目中命令模式无法实现的问题求助

问题概述 #

在Unity网球游戏项目中实现命令模式，已完成Command接口、LeftCommand/RightCommand命令类、Invoker调用类，以及关联Player的Character脚本，但按下左箭头键时角色毫无反应。

问题代码 #

Command.cs #

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public interface Command 
{
    void Execute();
}

RightCommand.cs #

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class RightCommand : Command
{
    Vector3 position;
    float speed = 3f;

    public RightCommand(Vector3 vector)
    {
        position = vector;
    }

    public void Execute()
    {
        position.x -= speed * Time.deltaTime;
    }
}

LeftCommand.cs #

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class LeftCommand : Command
{
    Vector3 position;
    float speed = 3f;

    public LeftCommand(Vector3 vector)
    {
        position = vector;
    }

    public void Execute()
    {
        position.x += speed * Time.deltaTime;
    }
}

Invoker.cs #

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Invoker 
{
    Stack<Command> mCommands;

    public Invoker()
    {
        mCommands = new Stack<Command>();
    }
    public void Execute(Command command)
    {
        if (command != null)
        {
            mCommands.Push(command);
            mCommands.Peek().Execute();
        }
    }
}

Character.cs #

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Character : MonoBehaviour
{
    public Leftmove left;
    float speed = 3f;
    float force = 10;
    bool hit;
    public Transform target;
    public Transform Tennisball;
    Animator animator;
    private Invoker minvoker;

    void Start()
    {
        minvoker = new Invoker();
        animator = GetComponent<Animator>();
    }

    void Update()
    {
        Vector3 position = transform.position;
        Vector3 positiont = target.position;

        if (Input.GetKeyDown(KeyCode.F))
        {
            hit = true;
        }
        else if (Input.GetKeyUp(KeyCode.F))
        {
            hit = false;
        }

        if (Input.GetKey(KeyCode.LeftArrow) && hit == false)
        {
            Command command = new LeftCommand(position);
            minvoker.Execute(command);
        }

        if (Input.GetKey(KeyCode.RightArrow) && hit == false)
        {
            position.x -= speed * Time.deltaTime;
        }

        if (Input.GetKey(KeyCode.UpArrow) && hit == false)
        {
            position.z -= speed * Time.deltaTime;
        }

        if (Input.GetKey(KeyCode.DownArrow) && hit == false)
        {
            position.z += speed * Time.deltaTime;
        }

        if ((hit == true) && (Input.GetKey(KeyCode.LeftArrow)))
        {
            positiont.x += speed * Time.deltaTime;
        }

        if ((hit == true) && (Input.GetKey(KeyCode.RightArrow)))
        {
            positiont.x -= speed * Time.deltaTime;
        }

        if ((hit == true) && (Input.GetKey(KeyCode.UpArrow)))
        {
            positiont.z -= speed * Time.deltaTime;
        }

        if ((hit == true) && (Input.GetKey(KeyCode.DownArrow)))
        {
            positiont.z += speed * Time.deltaTime;
        }

        transform.position = position;
        target.position = positiont;
    }

    private void OnTriggerEnter(Collider other)
    {
        if (other.CompareTag("Tennis ball"))
        {
            Vector3 dir = target.position - transform.position;
            other.GetComponent<Rigidbody>().velocity = dir.normalized * force + new Vector3(0, 10, 0);
            Vector3 side = Tennisball.position - transform.position;
            if (side.x >= 0)
            {
                animator.Play("backhand play");
            }
            else
            {
                animator.Play("forehand play");
            }
        }
    }
}

问题原因与修复方案 #

核心问题：值类型传递导致修改无效 #

Vector3是值类型，创建LeftCommand时传入的position是transform.position的副本，命令中修改的只是这个副本，不会影响角色的实际位置。命令类需要直接持有角色的Transform引用，才能真正修改位置。

修改后的命令类 #

LeftCommand.cs

using UnityEngine;

public class LeftCommand : Command
{
    private Transform _transform;
    private float _speed = 3f;

    // 传入角色的Transform引用
    public LeftCommand(Transform characterTransform)
    {
        _transform = characterTransform;
    }

    public void Execute()
    {
        // 直接修改Transform的位置，根据原有逻辑调整方向
        Vector3 newPos = _transform.position;
        newPos.x += _speed * Time.deltaTime;
        _transform.position = newPos;
    }
}

RightCommand.cs

using UnityEngine;

public class RightCommand : Command
{
    private Transform _transform;
    private float _speed = 3f;

    public RightCommand(Transform characterTransform)
    {
        _transform = characterTransform;
    }

    public void Execute()
    {
        Vector3 newPos = _transform.position;
        newPos.x -= _speed * Time.deltaTime;
        _transform.position = newPos;
    }
}

修改Character.cs中的调用逻辑 #

在左箭头键触发时，传入角色自身的transform而非position：

if (Input.GetKey(KeyCode.LeftArrow) && hit == false)
{
    Command command = new LeftCommand(transform);
    minvoker.Execute(command);
}

额外优化建议 #

• 避免重复创建命令实例：提前初始化左右命令对象，每次按键时复用，减少内存开销。
• 统一速度参数：将速度值提取为可配置的公共变量，在Character或命令类中统一管理，避免硬编码。
• 命令撤销逻辑：利用Invoker的栈结构添加Undo方法，弹出栈顶命令并执行反向操作（需为命令添加Undo接口）。

内容的提问来源于stack exchange，提问作者Dramus17