Unity3d 使用Raycast2D检测对象

我正在研究简单的策略游戏机制。我有一个兵营预制房。当我在场景中添加营房并单击营房时，我收到一个

NullReferenceException

错误：

NullReferenceException:对象引用未设置为对象PlacementController.Update（）的实例（位于Assets/Scripts/PlacementController.cs:64）

当我尝试使用Raycast2D访问营房的碰撞器名称时收到错误

营房预制有一个盒子碰撞R2D碰撞器（触发器已选中），其标签为“建筑”，其图层为“建筑”。它有一个刚体2D组件，是一个运动学刚体

我想不出这个问题。请帮帮我

谢谢你抽出时间

using UnityEngine;
using System.Collections;

public class PlacementController : MonoBehaviour
{
    private Buildings buildings;
    private Transform currentBuilding;
    private bool _hasPlaced;
    public LayerMask BuildingsMask;
    public void SelectBuilding(GameObject g)
    {
        _hasPlaced = false;
        currentBuilding = ((GameObject)Instantiate(g)).transform;
        buildings = currentBuilding.GetComponent<Buildings>();
    }

bool CheckPosition()
{
    if (buildings.CollidersList.Count > 0)
    {
        return false;
    }
    return true;
}

// Update is called once per frame
void Update () {


    Vector3 m = Input.mousePosition;
    m = new Vector3(m.x, m.y, transform.position.z);
    Vector3 p = GetComponent<Camera>().ScreenToWorldPoint(m);


    if (currentBuilding != null && !_hasPlaced)
    {

        currentBuilding.position = new Vector3(p.x,p.y,0);

        if (Input.GetMouseButtonDown(0))
        {
            if (CheckPosition())
            {
                _hasPlaced = true;
            }
        }
    }
    else
    {
        if (Input.GetMouseButtonDown(0))
        {
            RaycastHit2D hit = new RaycastHit2D();
            Ray2D ray2D = new Ray2D(new Vector2(p.x,p.y), Vector3.down );
            //Ray2D ray = new Ray(transform.position,new Vector3(p.x,p.y,p.z));
            if (Physics2D.Raycast(new Vector2(p.x,p.y),Vector3.down,5.0f,BuildingsMask) )
            {
                Debug.Log(hit.collider.name); //error
            }
        }
    }

}

---

Unity有两个物理引擎，它们非常相似，但这是一个以微妙和令人困惑的方式不同的领域

3D引擎提供，命中时返回

true

，否则返回

false

，如果需要了解更多命中信息，可以通过引用传递

RaycastHit

2D引擎提供，它在命中时返回

RaycastHit2D

，否则返回

null

。按照编写代码的方式，您访问的

命中

与raycast调用返回的命中不同

因此，您需要更接近这一点：

RaycastHit2D hit = Physics2D.Raycast(...); //edit in your raycast settings
if (hit) {
    //do something with the hit data
}

（您可能会注意到，

RaycastHit2D

隐式转换为

bool

）

---

Unity在很长一段时间内只拥有3D引擎，所以很多旧文档都会说这是唯一的一个。注意这一点。

在新的UI系统中，您不再需要像这样手动处理点击。只需在你的MonoBehavior上实现，并确保场景中有和存在。

好的！我查看了所有的互联网，没有人了解人们真正需要什么。当谈论raycast2D时，我终于找到了他们需要的东西，拿走了，并感到高兴。）我会尝试在任何地方发布答案，这样人们就可以很容易地找到它，如果它需要的话。 从相机屏幕到2D精灵，精灵应该与任何碰撞器，刚体上的精灵不需要

//create 2 empty places for objects

public RaycastHit2D hit;
public GameObject choosen;

//in update put click on mouse //take Method play by clicking mouse

void Update(){
if (Input.GetKeyDown (KeyCode.Mouse0)) {
    RayCaster ();
    }
}

// create raycast Method

void RayCaster (){
    RaycastHit2D ray = Physics2D.GetRayIntersection(Camera.main.ScreenPointToRay (Input.mousePosition));//making ray and object, taking mouse position on screen from camera
    if(!UnityEngine.EventSystems.EventSystem.current.IsPointerOverGameObject (-1)) {
        if (ray.collider != null) {// for non error, check maybe you hit none collider sprite
            hit = ray;// not hit is our obj from scene, but we cant work with it as an object
            choosen = hit.transform.gameObject;// making hit obj as normal object, now we can work with it like with 3Dobject, not as sprite
        }
    }
}

然后与choosen obj合作

---

把脚本放到相机上，现在每个人都会很高兴，因为在互联网上甚至unity3D社区都不了解人们对raycast2D的真正需求，希望将来他们能让这个功能变得更简单。）

谢谢@ааааааааааааа，我只是需要用鼠标位置击中一条射线，然后知道这个位置是否与一些2D游戏对象（如精灵）击中

我正在调用这个命中OnMouseUp（）方法

//create 2 empty places for objects

public RaycastHit2D hit;
public GameObject choosen;

//in update put click on mouse //take Method play by clicking mouse

void Update(){
if (Input.GetKeyDown (KeyCode.Mouse0)) {
    RayCaster ();
    }
}

// create raycast Method

void RayCaster (){
    RaycastHit2D ray = Physics2D.GetRayIntersection(Camera.main.ScreenPointToRay (Input.mousePosition));//making ray and object, taking mouse position on screen from camera
    if(!UnityEngine.EventSystems.EventSystem.current.IsPointerOverGameObject (-1)) {
        if (ray.collider != null) {// for non error, check maybe you hit none collider sprite
            hit = ray;// not hit is our obj from scene, but we cant work with it as an object
            choosen = hit.transform.gameObject;// making hit obj as normal object, now we can work with it like with 3Dobject, not as sprite
        }
    }
}

void OnMouseUp(){
    RaycastHit2D ray = Physics2D.GetRayIntersection(Camera.main.ScreenPointToRay(Input.mousePosition));

    if (ray)
    {
        GameObject hittedGameObject = ray.collider.gameObject;

        // Do something else

    }
}