Question

如何使用IBeginDragHandler并设置拖动位置以保持一致并且不会突然切换到GameObject的中心？

这是我在一个新位置抓取并对象并释放它们的简单代码。但是，我意识到通过角落抓取物体（2D）会自动将指针指向中心。离开这样的阻力只是感觉很破旧。

using UnityEngine;
using System.Collections;
using UnityEngine.EventSystems;

public class Draggable : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler {
    public void OnBeginDrag(PointerEventData eventData) {
        Debug.Log ("Started dragging");

    }

    public void OnDrag(PointerEventData eventData) {
        Debug.Log ("Currently dragging");
        this.transform.position = eventData.position;
    }

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

}

Answer 1

您需要使用偏移量。调用OnPointerDown时获取偏移量。在调用OnDrag时应用此偏移量。

对于2D Sprite：

Camera mainCamera;
float zAxis = 0;
Vector3 clickOffset = Vector3.zero;

// Use this for initialization
void Start()
{
    zAxis = transform.position.z;
}

public void OnPointerDown(PointerEventData eventData)
{
    clickOffset = transform.position - mainCamera.ScreenToWorldPoint(new Vector3(eventData.position.x, eventData.position.y, zAxis));
}

public void OnDrag(PointerEventData eventData)
{
    //Use Offset To Prevent Sprite from Jumping to where the finger is
    Vector3 tempVec = mainCamera.ScreenToWorldPoint(eventData.position) + clickOffset;
    tempVec.z = zAxis; //Make sure that the z zxis never change

    transform.position = tempVec;
}

public void OnEndDrag(PointerEventData eventData)
{

}

对于UI对象，偏移量仍然是相同的解决方案，但也应使用ScreenPointToLocalPointInRectangle。

public class Draggable : MonoBehaviour, IDragHandler, IBeginDragHandler
{
    public Canvas parentCanvas;
    Vector3 Offset = Vector3.zero;

    public void OnPointerDown(PointerEventData eventData)
    {
        Vector2 pos;
        RectTransformUtility.ScreenPointToLocalPointInRectangle(parentCanvas.transform as RectTransform, eventData.position, parentCanvas.worldCamera, out pos);
        Offset = transform.position - parentCanvas.transform.TransformPoint(pos);
    }

    public void OnDrag(PointerEventData eventData)
    {
        Vector2 movePos;
        RectTransformUtility.ScreenPointToLocalPointInRectangle(parentCanvas.transform as RectTransform, eventData.position, parentCanvas.worldCamera, out movePos);
        transform.position = parentCanvas.transform.TransformPoint(movePos) + Offset;
    }
}

拖动时，对象会跳转到中心

1 个答案: