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

public class PinPreciseDrag : MonoBehaviour
{

    Vector3 target_Screen;
    Vector3 target_World;
    Vector3 mouse_Screen;
    Vector3 mouse_World;
    Vector3 offset;
    bool IsClickTarget;

    private void Start()
    {
        IsClickTarget = false;
        target_Screen = Camera.main.WorldToScreenPoint(transform.position);
    }

    void Update()
    {
        if (Input.GetMouseButton(0) && IsClickTarget == true)
        {
            mouse_Screen = new Vector3(Input.mousePosition.x, Input.mousePosition.y, target_Screen.z);
            mouse_World = Camera.main.ScreenToWorldPoint(mouse_Screen);

            transform.position = mouse_World + offset;
        }
    }

    void OnMouseDown()
    {
        IsClickTarget = true;
        mouse_Screen = new Vector3(Input.mousePosition.x, Input.mousePosition.y, target_Screen.z);
        mouse_World = Camera.main.ScreenToWorldPoint(mouse_Screen);

        offset = transform.position - mouse_World;  //目标物体世界位置 减去 鼠标世界位置      
    }

}