注：本文章只是学习总结的笔记，视频链接

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一、获取到点击物体的Tansform（摁下鼠标左键的瞬间）

实现思路：通过Camera的ScreenPointToRay方法和Input.mousePosition鼠标坐标生成创建Ray射线，再通过Physics的Raycast方法和射线，获得被碰撞的物体相关信息存储在RaycastHit里。
实现代码：

using UnityEngine;public class 点击移动物体 : MonoBehaviour
{public Camera cam;public Transform 被点击物体;//clickedOBJ// Update is called once per framevoid Update(){if (Input.GetMouseButtonDown(0)) {Ray ray = cam.ScreenPointToRay(Input.mousePosition);RaycastHit hit;Physics.Raycast(ray, out hit);被点击物体 = hit.transform;}}
}

二、移动点击的物体（摁着鼠标左键不放）

思路：通过相机的射线和距离获得一个点，设置给物体从而达到移动物体。
距离如何获取：
方法一：获取到点击物体时hit对象中存射线起点到碰撞点的距离
方法二：通过两个点算一个距离，也就的那被移动对象的坐标和相机坐标算一个距离
代码如下：

using System.Globalization;
using UnityEngine;public class 点击移动物体 : MonoBehaviour
{public Camera cam;public Transform 被点击物体;//clickedOBJpublic float 距离;//distance// Update is called once per framevoid Update(){if (Input.GetMouseButtonDown(0)) {Ray ray = cam.ScreenPointToRay(Input.mousePosition);RaycastHit hit;if(Physics.Raycast(ray, out hit)){被点击物体 = hit.transform;距离 = Vector3.Distance(cam.transform.position, hit.transform.position);float 距离1 = hit.distance; //这是视频老师写的获取应该相机和碰撞点的距离Debug.Log($"1:{距离}\n2:{距离1}");}}if(Input.GetMouseButton(0)){if(被点击物体){Ray ray = cam.ScreenPointToRay(Input.mousePosition);被点击物体.position = ray.GetPoint(距离);}}}
}

三、松开左键清理被移动对象属性

using System.Globalization;
using UnityEngine;public class 点击移动物体 : MonoBehaviour
{public Camera cam;public Transform 被点击物体;//clickedOBJpublic float 距离;//distance// Start is called once before the first execution of Update after the MonoBehaviour is createdvoid Start(){}// Update is called once per framevoid Update(){if (Input.GetMouseButtonDown(0)) {Ray ray = cam.ScreenPointToRay(Input.mousePosition);RaycastHit hit;if(Physics.Raycast(ray, out hit)){被点击物体 = hit.transform;距离 = Vector3.Distance(cam.transform.position, hit.transform.position);float 距离1 = hit.distance; //这是视频老师写的获取应该相机和碰撞点的距离Debug.Log($"1:{距离}\n2:{距离1}");}}if(Input.GetMouseButton(0)){if(被点击物体){Ray ray = cam.ScreenPointToRay(Input.mousePosition);被点击物体.position = ray.GetPoint(距离);}}if (Input.GetMouseButtonUp(0)) {被点击物体 = null;}}
}

总结

射线生成，射线检测，射线+距离获得坐标