更改线宽出错，对象引用未设置为对象的实例

Question

我希望能够更改线宽，但我似乎运行遇到了一些问题。我设置它的方式是我有 6 种不同的线宽，当用户点击宽度时，下次他们画线时应该反映出来。目前我收到错误：

"NullReferenceException: 对象引用未设置到对象的实例 BrushWidth.SetThickness (Int32 _lineNum) (at Assets/_Scripts/BrushWidth.cs:46) BrushWidth.Start () (at Assets/_Scripts/BrushWidth.cs:30)”

这是指改变线比例的线，lineConfig.Scale = 0.35f ;

我在这里错过了什么？我以为我用 public LineConfig lineConfig 做了我的实例引用；感谢您的帮助！

using UnityEngine ;
using System.Collections ;
using UnityEngine.UI ;
using System ;
using PaintCraft.Tools ;

public class BrushWidth : MonoBehaviour
{
    public Button btn1, btn2, btn3, btn4, btn5, btn6 ;
    public float brushSize ;
    public Text brushNameTextBox ;
    public String brushName ;
    public LineConfig lineConfig ;

    void Awake ()
    {
        lineConfig = gameObject.GetComponent<LineConfig> () ;

        btn1.onClick.AddListener (() => SetThickness (1)) ;
        btn2.onClick.AddListener (() => SetThickness (2)) ;
        btn3.onClick.AddListener (() => SetThickness (3)) ;
        btn4.onClick.AddListener (() => SetThickness (4)) ;
        btn5.onClick.AddListener (() => SetThickness (5)) ;
        btn6.onClick.AddListener (() => SetThickness (6)) ;
    }

    void Start ()
    {
        // Set Starting Thickness
        SetThickness (3) ;
    }

    void SetThickness (int _lineNum)
    {
        switch (_lineNum)
        {
            case 1:
                lineConfig.Scale = 0.1f ;
                brushName = "Thin  " ;
                break ;
            case 2:
                lineConfig.Scale = 0.2f ;
                brushName = "Light  " ;
                break ;
            case 3:
                lineConfig.Scale = 0.35f ;
                brushName = "Regular  " ;
                break ;
            case 4:
                lineConfig.Scale = 0.5f ;
                brushName = "Medium  " ;
                break ;
            case 5:
                lineConfig.Scale = 0.75f ;
                brushName = "Thick  " ;
                break ;
            case 6:
                lineConfig.Scale = 1.0f ;
                brushName = "Heavy  " ;
                break ;
            default:
                break ;
        }
        brushNameTextBox.text = brushName ;
    }
}

Answer 1

您的问题是您没有将 LineConfig 组件附加到您的脚本所附加的对象。因此，GetComponent returns 无效。要解决此问题，请将 LineComponent 添加到您的对象，或简单地更改：

lineConfig = gameObject.GetComponent<LineConfig> () ;

至：

lineConfig = gameObject.AddComponent<LineConfig>() ;

或者，如果您想确保已经附加了 LineConfig，请将 [RequireComponent (typeof (LineConfig))] 添加到 class 的开头，高于 public class BrushWidth : MonoBehaviour。所以，你的 class 应该是这样的：

using UnityEngine ;
using System.Collections ;
using UnityEngine.UI ;
using System ;
using PaintCraft.Tools ;
public class BrushWidth : MonoBehaviour
{
public Button btn1, btn2, btn3, btn4, btn5, btn6 ;
public float brushSize ;
public Text brushNameTextBox ;
public String brushName ;
public LineConfig lineConfig ;

void Awake ()
{
    lineConfig = gameObject.AddComponent<LineConfig> () ;

    btn1.onClick.AddListener (() => SetThickness (1)) ;
    btn2.onClick.AddListener (() => SetThickness (2)) ;
    btn3.onClick.AddListener (() => SetThickness (3)) ;
    btn4.onClick.AddListener (() => SetThickness (4)) ;
    btn5.onClick.AddListener (() => SetThickness (5)) ;
    btn6.onClick.AddListener (() => SetThickness (6)) ;
}

void Start ()
{
    // Set Starting Thickness
    SetThickness (3) ;
}

void SetThickness (int _lineNum)
{
    switch (_lineNum)
    {
        case 1:
            lineConfig.Scale = 0.1f ;
            brushName = "Thin  " ;
            break ;
        case 2:
            lineConfig.Scale = 0.2f ;
            brushName = "Light  " ;
            break ;
        case 3:
            lineConfig.Scale = 0.35f ;
            brushName = "Regular  " ;
            break ;
        case 4:
            lineConfig.Scale = 0.5f ;
            brushName = "Medium  " ;
            break ;
        case 5:
            lineConfig.Scale = 0.75f ;
            brushName = "Thick  " ;
            break ;
        case 6:
            lineConfig.Scale = 1.0f ;
            brushName = "Heavy  " ;
            break ;
        default:
            break ;
    }
    brushNameTextBox.text = brushName ;
}
}

希望对您有所帮助 :)

更改线宽出错，对象引用未设置为对象的实例

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