Unity3D UI，计算拖动项目的位置? [英] Unity3D UI, calculation for position dragging an item?

问题描述

如今在 Unity 中拖动 UI 元素非常容易:制作一些 UI 项目.添加组件 -> 事件 -> 事件触发器.放下下面的脚本.单击以添加四个明显的触发器.大功告成.

These days it's incredibly easy to drag UI elements in Unity: Make a few UI items. Add Component -> Event -> Event Trigger. Drop on the script below. Click to add the four obvious triggers. You're done.

不过.

我完全迷失在指针坐标和UI坐标之间的关系(如RectTransform等中所见).

I'm totally lost in the relationship between pointer coordinates and UI coordinates (as seen in RectTransform and so on).

在下面的 DragIt 中:你到底是如何在手指下正确移动 UI 面板的?

In DragIt below: how the hell do you move a UI panel correctly under the finger?

假设您有一个大面板，面板中有十个 UIButton，按钮上有 Dragster.RectTransform坐标和鼠标指针有什么关系...

Say you have one large panel, with ten UIButton sitting in the panel with Dragster on the buttons. What is the relationship between the RectTransform coords and the mouse pointer ...

简而言之，您如何在下面的 DragIt() 处移动按钮之一?

in short how do you move one of the button around at DragIt() below?

/* modern Unity drag of UI element */
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.Events;
using UnityEngine.EventSystems;
public class Dragster:MonoBehaviour
    {
    public int index; // number each of your UI items
    static bool beingDragged = false;
    static int dragFrom;
    public void DragStart()
        {
        beingDragged = true; dragFrom = index;
        }
    public void DragIt()
        {
        ? ? W T F ? ?
        }
    public void DragEnd()
        {
        beingDragged = false;
        }
    public void DroppedBra()
        {
        Debig.Log("Drag: from/to " +dragFrom +" --> " +index);
        }
    }

推荐答案

对于拖动东西，我只是这样做:

For Draging stuff I just do this :

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;

public class Draggable : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler {
    
    
    
    public void OnBeginDrag(PointerEventData eventData) {
        
    }
    
    public void OnDrag(PointerEventData eventData) {
        //Debug.Log ("OnDrag");
        
        this.transform.position = eventData.position;

        }

    public void OnEndDrag(PointerEventData eventData) {
        Debug.Log ("OnEndDrag");
    
    }
}

这是同样惊人的 URIPOPOV CODE，它具有两个简单的功能，您在拖动时总是需要这些功能:

Here's the identical amazing URIPOPOV CODE with two simple features which you always need when dragging:

// allow dragging with two basic problem fixes:
// - limit drag to the parent box
// - don't "jump" based on where you hold down

100% 测试:

using UnityEngine;
using UnityEngine.EventSystems;

public class AmazingUPDrag : MonoBehaviour,
               IBeginDragHandler, IDragHandler, IEndDragHandler
{
    Vector2 dragOffset = Vector2.zero;
    Vector2 limits = Vector2.zero;

    public void OnBeginDrag(PointerEventData eventData)
    {
        dragOffset = eventData.position - (Vector2)transform.position;
        limits = transform.parent.GetComponent<RectTransform>().rect.max;
    }

    public void OnDrag(PointerEventData eventData)
    {
        transform.position = eventData.position - dragOffset;
        var p = transform.localPosition;
        if (p.x < -limits.x) { p.x = -limits.x; }
        if (p.x > limits.x) { p.x = limits.x; }
        if (p.y < -limits.y) { p.y = -limits.y; }
        if (p.y > limits.y) { p.y = limits.y; }
        transform.localPosition = p;
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        dragOffset = Vector2.zero;
    }
}

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