如何知道点击了哪个按钮？ (Unity/Hololens2/MRTK)

Question

我有大约 10 个按钮，每个按钮都有一个通过脚本添加的唯一值。我想知道使用 MRTK 手与按钮交互时单击了哪个按钮。

我尝试向使用默认 EventSystem 获取当前选定对象的按钮添加一个 updateField 方法。但是，当我调试时，该值为 null。

public void UpdateField()
{
      int dayNumb = EventSystem.current.currentSelectedGameObject.GetComponent<DayButton>().CurrentNumber();
}

NullReferenceException：对象引用未设置为 对象 UpdateInputField.UpdateField () (在 资产/脚本/UpdateInputField.cs:35) UnityEngine.Events.InvokableCall.Invoke() (在 C:/buildslave/unity/build/Runtime/Export/UnityEvent.cs:166) UnityEngine.Events.UnityEvent.Invoke () (在 C:/buildslave/unity/build/Runtime/Export/UnityEvent_0.cs:58) Microsoft.MixedReality.Toolkit.UI.InteractableOnPressReceiver.OnUpdate （Microsoft.MixedReality.Toolkit.UI.InteractableStates 状态， Microsoft.MixedReality.Toolkit.UI.Interactable 源）（在 资产/MixedRealityToolkit.SDK/Features/UX/Interactable/Scripts/Events/InteractableOnPressReceiver.cs:71) Microsoft.MixedReality.Toolkit.UI.Interactable.InternalUpdate () (在 资产/MixedRealityToolkit.SDK/Features/UX/Interactable/Scripts/Interactable.cs:525) Microsoft.MixedReality.Toolkit.UI.Interactable.Update () (在 Assets/MixedRealityToolkit.SDK/Features/UX/Interactable/Scripts/Interactable.cs:506)

Answer 1

以下代码将打印场景中被点击的每个按钮的名称。请注意，您可以在从代码创建按钮时添加这些侦听器，而不是在启动时添加事件侦听器。

using Microsoft.MixedReality.Toolkit.UI;
using UnityEngine;

/// <summary>
/// On startup, adds event handlers for every Interactable aka button
/// in the scene that logs the name of the button pressed.
/// You can similarly add such a listener when adding the buttons dynamically
/// </summary>
public class PrintWhichButtonPressed : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {
        var allInteractables = GameObject.FindObjectsOfType<Interactable>();
        foreach (var i in allInteractables)
        {
            i.OnClick.AddListener(() => Debug.Log(Time.time + ": " + i.gameObject.name + " was clicked"));
        }
    }
}

Answer 2

关于异常

EventSystem.current.currentSelectedGameObject.GetComponent<DayButton>().CurrentNumber();

提供了很多可能性。基本上每个. 之前的引用都可能是null。最有可能的是currentSelectedGameObject（当当前根本没有选择对象时）或GetComponent<DayButton>()（当所选对象根本没有这样的组件时）。

---

我对你的课程一无所知，对 MRTK 也知之甚少，但也许你可以使用事件系统模式，例如

public class DayButton : WhateverType
{
    // public static event everyone can add listeners to 
    // in order to wait for any DayButton click
    public static event Action<DayButton> OnButtonClicked;

    // Just assuming for now this is the method called on click
    public void OnClick()
    {
        // Fire the static event and inform every listener
        // that this button was clicked by passing yourself in as parameter
        OnButtonClicked?.Invoke(this);
    }
}

然后你可以让一个（或不同的）监听器类等待事件并检查按下了哪个按钮

public class SomeListener : MonoBehaviour
{
    privtae void Awake()
    {
        // Add a listener to the global event
        DayButton.OnButtonClicked += HandleOnButtonClicked;
    }

    private void OnDestroy()
    {
        // Make sure to always remove listeners once not needed anymore
        // otherwise you get NullReferenceExceptions!
        DayButton.OnButtonClicked -= HandleOnButtonClicked;
    }

    // By passing the according DayButton reference in you have access
    // to all its public fields and methods
    private void HandleOnButtonClicked(DayButton button)
    {
        Debug.Log("The Button with the name {button.name} and number {button.CurrentNumber} was clicked!", this);
    }
}

Answer 3

解决了！！ 我在 start 方法的每个按钮上添加了一个监听器。然后调用该函数来获取这些对象的组件。

这就是我的做法............

using UnityEngine.UI;
using UnityEngine.EventSystems;
using UnityEditor;
using Microsoft.MixedReality.Toolkit.UI;

public class UpdateInputField : MonoBehaviour {
    public InputField mainInputField;
    private Calendar calendar;
    private GameObject dateCanvas;
    public int dayNumb;

    void Start(){
        var allInteractables = GameObject.FindObjectsOfType<Interactable>();
        foreach (var i in allInteractables)
        {
            i.OnClick.AddListener(() => UpdateField(i));
        }
    }

    public void UpdateField(Microsoft.MixedReality.Toolkit.UI.Interactable index)
    {
        dayNumb = GameObject.Find(index.gameObject.name).GetComponent<DayButton>().CurrentNumber();
        calendar = GameObject.FindObjectOfType<Calendar>();
        mainInputField.text = calendar.ReturnDate(dayNumb);     
    }
}