using UnityEngine;
/*
 讓物體完全跟隨鼠標
  */
public class MouseMove : MonoBehaviour
{
 [Header("主相機")]
 [Tooltip("主相機")]
 /// <summary>
 /// 主相機
 /// </summary>
 public Camera m_mainCamera;
 [Header("目標物體")]
 [Tooltip("目標物體")]
 /// <summary>
 /// 目標物體
 /// </summary>
 public Transform m_target;
 
 void Start()
 {
  isDown = false;
  targetWTSP = m_mainCamera.WorldToScreenPoint(m_target.position);
 }
 /// <summary>
 /// 是否按下
 /// </summary>
 private bool isDown;
 /// <summary>
 /// 記錄初始化時候target世界坐標轉屏幕坐標時候的位置 WTSP==WorldToScreenPoint
 /// </summary>
 private Vector3 targetWTSP;
 void Update()
 {
  if (Input.GetMouseButtonDown(0)) {
   isDown = true;
  }
  if (Input.GetMouseButtonUp(0))
  {
   isDown = false;
  }
 }
 private void LateUpdate()
 {
  if (isDown)
  {
   Vector3 mouseVec3 = m_mainCamera.ScreenToWorldPoint(
    new Vector3(Input.mousePosition.x, Input.mousePosition.y, targetWTSP.z)
   );
   m_target.position = mouseVec3;
  }
 }
}