执行raycast时Camera.main为null [英] Camera.main is null when performing raycast

问题描述

产生错误的代码:

void Update()
{
    if (Input.touchCount > 0)
    {
        RaycastHit2D hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.GetTouch(0).position), Vector2.zero);
        if (hit && hit.collider != null && hit.collider.name == "leftTapArea")
        {
            hit.transform.name = "Hit";
        }
    }
}

它表示此字符串有问题:

It says that something is wrong with this string:

RaycastHit2D hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.GetTouch(0).position)，Vector2.zero);

RaycastHit2D hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.GetTouch(0).position), Vector2.zero);

错误:

NullReferenceException:对象引用未设置为对象的实例 leftScript.Update()(位于Assets/leftScript.cs:16)

NullReferenceException: Object reference not set to an instance of an object leftScript.Update () (at Assets/leftScript.cs:16)

推荐答案

在代码中唯一可以返回null的是Camera.main.ScreenToWorldPoint.这意味着Camera.main是null.为了初始化Camera.main，摄像机必须具有MainCamera标签.

The only thing that can return null in your code is Camera.main.ScreenToWorldPoint. It means that Camera.main is null. For Camera.main to be initialized, the camera must have the MainCamera tag.

选择Camera GameObject，然后将标签更改为MainCamera.

Select the Camera GameObject then change the tag to MainCamera.

如果您不希望相机位于MainCamera标签中，也可以直接使用GameObject.Find查找机智，然后从中获取Camera组件.

If you don't want your camera to be in the MainCamera tag, you can also find wit directly with GameObject.Find then get the Camera component from it.

Camera cam;

void Start()
{
    cam = GameObject.Find("NameOfCameraGameObject").GetComponent<Camera>();
}

void Update()
{
    if (Input.touchCount > 0)
    {
        RaycastHit2D hit = Physics2D.Raycast(cam.ScreenToWorldPoint(Input.GetTouch(0).position), Vector2.zero);
        if (hit && hit.collider != null && hit.collider.name == "leftTapArea")
        {
            hit.transform.name = "Hit";
        }
    }
}

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