Unity第三人称肩视角相机移动实现方案技术咨询

我在开发Unity相机控制器时进度缓慢，没法构思出可行的实现方案。目前已经通过新输入系统获取了鼠标输入并传入lookInput变量，还定义了mouseDelta但没用到，以下是修改后的代码，求技术帮助：

这是我在评论中提到的修改版本。

using UnityEngine.InputSystem;
using UnityEngine;

public class CameraController : MonoBehaviour
{
    public InputActionAsset cameraInputs;
    private InputActionMap cameraMap;
    private InputAction lookAction;

    public float sensitivity = 10f;

    public Transform player;

    private Vector2 lookInput;

    public Vector3 defaultCameraPosition;
    private Vector3 initialOffset;
    private void Awake()
    {
        cameraMap = cameraInputs.FindActionMap("CameraMap");
        lookAction = cameraMap.FindAction("Look");
        lookAction.performed += OnLookPerformed;
    }

    private void Start()
    {
        transform.position = defaultCameraPosition;

        if (player == null)
        {
            initialOffset = transform.position - player.position;

            transform.LookAt(player.position);
        }

        Cursor.lockState = CursorLockMode.Locked;
        Cursor.visible = false;
    }

    private void Update()
    {
        Vector3 mouseDelta = new Vector3(-lookInput.y, lookInput.x, 0f) * sensitivity * Time.deltaTime;
    }

    private void LateUpdate()
    {
        RotateCamera();
    }

    private void OnEnable()
    {
        cameraMap.Enable();
    }

    private void OnDisable()
    {
        cameraMap.Disable();
    }

    private void OnLookPerformed(InputAction.CallbackContext context)
    {
        lookInput = context.ReadValue<Vector2>();
    }

    private void RotateCamera()
    {
        float yaw = lookInput.x * sensitivity * Time.deltaTime;
        float pitch = -lookInput.y * sensitivity * Time.deltaTime;

        player.Rotate(0f, yaw, 0f, Space.World);

        Vector3 currentRotation = player.transform.localEulerAngles;
        float newPitch = currentRotation.x + pitch;

        float maxPitch = 80f;
        newPitch = Mathf.Clamp(newPitch, -maxPitch, maxPitch);

        player.transform.localEulerAngles = new Vector3(newPitch, currentRotation.y, currentRotation.z);

        transform.LookAt(player.position);
    }
}

问题分析与修复建议 #

1. 空指针判断逻辑错误
   Start方法里的if (player == null)写反了，应该是if (player != null)，否则当player为空时执行player.position会触发空引用报错。

2. 相机旋转逻辑错误
   当前代码把俯仰（上下拖动）和偏航（左右拖动）都应用在player上，会导致玩家模型跟着抬头低头，不符合常规第三人称相机逻辑。正确逻辑是：

   • 偏航（左右拖动）旋转player
   • 俯仰（上下拖动）旋转相机本身，同时限制俯仰角度

3. initialOffset未被使用
   应该在LateUpdate中通过这个变量维持相机与player的相对位置，避免相机位置漂移。

4. mouseDelta变量冗余
   当前Update里定义了mouseDelta但未使用，可直接删除，或在RotateCamera中复用该计算逻辑。

修复后的代码示例 #

using UnityEngine.InputSystem;
using UnityEngine;

public class CameraController : MonoBehaviour
{
    public InputActionAsset cameraInputs;
    private InputActionMap cameraMap;
    private InputAction lookAction;

    public float sensitivity = 10f;
    public Transform player;

    private Vector2 lookInput;
    private Vector3 initialOffset;
    // 单独存储俯仰角度，避免欧拉角万向锁和角度范围异常
    private float currentPitch = 0f;
    public float maxPitch = 80f;

    private void Awake()
    {
        cameraMap = cameraInputs.FindActionMap("CameraMap");
        lookAction = cameraMap.FindAction("Look");
        lookAction.performed += OnLookPerformed;
    }

    private void Start()
    {
        Cursor.lockState = CursorLockMode.Locked;
        Cursor.visible = false;

        if (player != null)
        {
            // 记录相机与玩家的初始相对偏移
            initialOffset = transform.position - player.position;
            // 初始化俯仰角度并修正欧拉角0-360度范围问题
            currentPitch = transform.localEulerAngles.x;
            if (currentPitch > 180f) currentPitch -= 360f;
        }
    }

    private void LateUpdate()
    {
        if (player == null) return;
        
        // 处理偏航：旋转玩家
        float yaw = lookInput.x * sensitivity * Time.deltaTime;
        player.Rotate(Vector3.up, yaw, Space.World);

        // 处理俯仰：旋转相机并限制角度
        currentPitch += -lookInput.y * sensitivity * Time.deltaTime;
        currentPitch = Mathf.Clamp(currentPitch, -maxPitch, maxPitch);

        // 更新相机位置和旋转
        Quaternion playerYawRotation = Quaternion.Euler(0, player.eulerAngles.y, 0);
        transform.position = player.position + playerYawRotation * initialOffset;
        transform.rotation = playerYawRotation * Quaternion.Euler(currentPitch, 0, 0);
    }

    private void OnEnable()
    {
        cameraMap.Enable();
    }

    private void OnDisable()
    {
        cameraMap.Disable();
    }

    private void OnLookPerformed(InputAction.CallbackContext context)
    {
        lookInput = context.ReadValue<Vector2>();
    }
}

关键优化说明 #

• 分离玩家旋转（偏航）和相机旋转（俯仰），符合常规第三人称视角逻辑
• 使用独立变量存储俯仰角度，避免欧拉角的万向锁问题和角度范围异常
• 通过玩家旋转更新相机位置，维持初始相对距离和方向
• 修复空指针判断逻辑，避免运行时错误

内容的提问来源于stack exchange，提问作者user20658958