执行光线投射时，Camera.main 为空 [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";
        }
    }
}

它说这个字符串有问题:

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: 未将对象引用设置为对象的实例leftScript.Update ()(在 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

在您的代码中唯一可以返回 null 的是 Camera.main.ScreenToWorldPoint.这意味着 Camera.main 是 null.要初始化 Camera.main，相机必须具有 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.

如果您不希望您的相机位于 MainCamera 标签中，您也可以直接使用 GameObject.Find 找到 wit，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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