Unity3D 入门小技巧——鼠标拾取并移动物体

一、鼠标拾取物体的原理

在Unity3D当中，想要在观察面(Aspect)中拾取物体(有碰撞属性)的方法一般如下：

1、声明一个观察的摄像机、一个从摄像机原点出发的射线Ray以及一个用于检测碰撞的RaycastHit；

2、将射线Ray定义为从摄像机原点出发并且指向当前鼠标所在的坐标(屏幕坐标)；

3、定义碰撞RaycastHit为射线Ray与有碰撞属性的物体的碰撞点。

具体代码实现如下(C#代码)：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class camera : MonoBehaviour
{public Camera ca;private Ray ra;private RaycastHit hit;// Use this for initializationvoid Start(){}// Update is called once per framevoid Update(){ra = ca.ScreenPointToRay(Input.mousePosition);if (Physics.Raycast(ra, out hit)){  }}
}

应用一：当鼠标按住不动时，移动被选定物体随鼠标一起移动

using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class camera : MonoBehaviour
{public Camera ca;private Ray ra;private RaycastHit hit;// Use this for initializationvoid Start(){}// Update is called once per framevoid Update(){if (Input.GetMouseButton(0)){ra = ca.ScreenPointToRay(Input.mousePosition);if (Physics.Raycast(ra, out hit)){hit.collider.gameObject.transform.position = ca.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, hit.collider.gameObject.transform.position.z));}}}
}

应用二：当鼠标点击物体时，物体随鼠标一起移动；当鼠标再次点击时，放下物体。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class camera : MonoBehaviour {public Camera ca;private Ray ra;private RaycastHit hit;private int flag = 0;// Use this for initializationvoid Start () {}// Update is called once per framevoid Update () {if (Input.GetMouseButtonDown(0)){ra = ca.ScreenPointToRay(Input.mousePosition);if (Physics.Raycast(ra, out hit)){if (flag == 0){flag = 1;} else{flag = 0;}}}if (flag == 1){hit.collider.gameObject.transform.position = ca.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, hit.collider.gameObject.transform.position.z));}}
}