unity如何实现控制视角的同时实现拖拽物体移动

在使用UNITY有两个脚本，我在unity写了两个C#脚本，一个是通过键盘鼠标控制视角的，另一个是通过鼠标拖拽移动物体的。但是当通过键盘鼠标控制视角的脚本运行之后，通过鼠标拖拽移动物体的脚本就很难起作用，具体表现为：键盘鼠标控制视角的脚本运行之后，多次点击并尝试拖拽物体失败，被拖拽物体不会有任何反应，这主要是因为代码无法准确识别点击的对象，常常会认为鼠标点击的是其它物体，例如物体下方的地板。代码如下，请各位不吝赐教：

// 通过键盘鼠标控制视角的脚本
using UnityEngine;
 
public class FirstPersonController : MonoBehaviour
{
    public float moveSpeed = 5.0f;

    public float lookSpeed = 2.0f;

    public float lookXLimit = 45.0f;
 
    private float rotationY;

    private float rotationX;

    private CharacterController controller;
 
    void Start()
    {
        Cursor.lockState = CursorLockMode.Locked;

        controller = GetComponent<
CharacterController>
();

    } 
    void Update()
    {
        if (Input.GetMouseButton(0))
        {
            rotationX -= Input.GetAxis("
Mouse Y"
) * lookSpeed;

            rotationY += Input.GetAxis("
Mouse X"
) * lookSpeed;

            rotationX = Mathf.Clamp(rotationX, -lookXLimit, lookXLimit);

            transform.localRotation = Quaternion.Euler(rotationX, rotationY, 0);

            transform.GetChild(0).localRotation = Quaternion.Euler(0, rotationY, 0);

        } 
        float moveX = Input.GetAxis("
Horizontal"
);

        float moveZ = Input.GetAxis("
Vertical"
);
 
        Vector3 moveDir = new Vector3(moveX, 0, moveZ).normalized;

        moveDir = transform.TransformDirection(moveDir);

        moveDir.y = 0;

        controller.Move(moveDir * moveSpeed * Time.deltaTime);

    }
}

// 通过鼠标拖拽移动物体的脚本
using UnityEngine;
 
public class DragObject : MonoBehaviour
{
    private bool dragging = false;

    private Vector3 screenPoint;

    private Vector3 offset;
 
    void OnMouseDown()
    {
        screenPoint = Camera.main.WorldToScreenPoint(gameObject.transform.position);

        offset = gameObject.transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z));

        dragging = true;

    } 
    void OnMouseUp()
    {
        dragging = false;

    } 
    void OnMouseDrag()
    {
        if (dragging)
        {
            Vector3 mousePosition = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z);

            gameObject.transform.position = Camera.main.ScreenToWorldPoint(mousePosition) + offset;

        }
    }
}