Unity 3D第三人称相机开发遇CS0103错误：targetAngle未定义

错误原因 #

targetAngle是在if(direction.magnitude >= 0.1f)代码块内部声明的局部变量，作用域仅局限于该代码块。当你在代码块外的Vector3 moveDir = Quaternion.Euler(0f, targetAngle, 0f) * Vector3.forward;语句中访问它时，编译器找不到这个变量，因此抛出CS0103错误。

修复步骤 #

1. 将targetAngle的声明移到if代码块之外，确保它的作用域覆盖到后续使用它的代码；
2. 修正Start方法里的错误：_playerMove是bool类型，你却给它赋值GetComponent<PlayerMovement>()，这会导致类型不匹配错误，直接删除这句即可。

修改后的完整代码 #

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

public class PlayerMovement : MonoBehaviour
{
    public CharacterController controller;
    public Transform cam;

    public float speed = 12f;
    public float gravity = -9.81f;
    public float jumpHeight = 3f;
    public float _doubleJumpMultiplier = 1.5f;
    public float turnSmoothTime = 0.1f;
    private float turnSmoothVelocity;

    public Transform groundCheck;
    public float groundDistance = 0.4f;
    public LayerMask groundMask; 

    Vector3 velocity;
    bool isGrounded;
    private bool _canDoubleJump = false;
    bool _playerMove = false;

    private void Start()
    {
        // 移除错误的赋值语句：_playerMove是bool类型，不能赋值PlayerMovement组件
    }

    void Update()
    {
        isGrounded = Physics.CheckSphere(groundCheck.position, groundDistance, groundMask);

        if(isGrounded && velocity.y < 0) 
        {
            _canDoubleJump = true;
            velocity.y = -2f;
        }
        else 
        {
            if(Input.GetButtonDown("Jump") && _canDoubleJump) 
            {
                velocity.y = 3f * _doubleJumpMultiplier;
                _canDoubleJump = false;
            }
        }

        float vertical = Input.GetAxisRaw("Vertical");
        float horizontal = Input.GetAxisRaw("Horizontal");
        Vector3 direction = new Vector3(horizontal, 0f, vertical).normalized;

        // 提前声明targetAngle并初始化默认值
        float targetAngle = transform.eulerAngles.y;
        if(direction.magnitude >= 0.1f) 
        {
            // 这里不再重新声明，直接赋值
            targetAngle = Mathf.Atan2(direction.x, direction.z) * Mathf.Rad2Deg + cam.eulerAngles.y;
            float angle = Mathf.SmoothDampAngle(transform.eulerAngles.y, targetAngle, ref turnSmoothVelocity, turnSmoothTime);
            transform.rotation = Quaternion.Euler(0f, angle, 0f);
        }

        Vector3 moveDir = Quaternion.Euler(0f, targetAngle, 0f) * Vector3.forward;
        controller.Move(moveDir * speed * Time.deltaTime);

        if(Input.GetButtonDown("Vertical") && isGrounded && _canDoubleJump) 
        {
            _playerMove = true;
        }  
        else if(!Input.GetButtonDown("Vertical") && isGrounded && _canDoubleJump) 
        {
            _playerMove = false;
        } 

        if(Input.GetButtonDown("Horizontal") && isGrounded && _canDoubleJump) 
        {
            _playerMove = true;
        }  
        else if(!Input.GetButtonDown("Horizontal") && isGrounded && _canDoubleJump) 
        {
            _playerMove = false;
        }

        if(Input.GetButtonDown("Jump") && isGrounded)
        {
            velocity.y = Mathf.Sqrt(jumpHeight * -2 * gravity);
        }

        velocity.y += gravity * Time.deltaTime;
        controller.Move(velocity * Time.deltaTime);
    }
}

额外说明 #

把targetAngle的初始值设为transform.eulerAngles.y，可以让玩家在静止时保持当前朝向，避免无输入时移动方向跳转到世界正前方。

内容的提问来源于stack exchange，提问作者RedWolf