试图用鼠标统一拖动一个对象，我不断收到同样的错误

Question

脚本已附加到我尝试拖动的游戏对象，错误状态为：

NullReferenceException，对象引用未设置到对象的实例

它指向我脚本的第 25 行：

distance = Vector3.Distance(transform.position, Camera.main.transform.position);

这是完整的脚本：

using System.Collections;
using UnityEngine;

class DragTransform : MonoBehaviour

{

    private Color mouseOverColor = Color.blue;
    private Color originalColor = Color.yellow;
    private bool dragging = false;
    private float distance;


    void OnMouseEnter()
    {
        GetComponent<Renderer>().material.color = mouseOverColor;
    }

    void OnMouseExit()
    {
        GetComponent<Renderer>().material.color = originalColor;
    }

    void OnMouseDown()
    {
        distance = Vector3.Distance(transform.position, Camera.main.transform.position);
        dragging = true;
    }

    void OnMouseUp()
    {
        dragging = false;
    }

    void Update()
    {
        if (dragging)
        {
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            Vector3 rayPoint = ray.GetPoint(distance);
            transform.position = rayPoint;
        }
    }
}

非常感谢大家的帮助！谢谢！

Answer 1

如果没有相机标记为 MainCamera，

Camera.main 将 return 为空。 https://docs.unity3d.com/ScriptReference/Camera-main.html

您需要将主摄像头标记为MainCamera。

试图用鼠标统一拖动一个对象，我不断收到同样的错误

Trying to drag an object with mouse in unity, I keep getting the same error

c#

nullreferenceexception

unity3d

unity5