Unity学习笔记 鼠标点击拖拽等

1.使用unity内置方法 OnMouseXXX（），需要目标有碰撞体。适合2D贴图和3D场景使用。ui的拖动使用下面两种方法。

 /// <summary>
		    /// Called when the mouse enters the GUIElement or Collider.
		    /// </summary>
		    void OnMouseEnter ()
		
		    /// <summary>
		    /// Called when the mouse is not any longer over the GUIElement or Collider.
		    /// </summary>
		    void OnMouseExit ()
		
		    /// <summary>
		    /// OnMouseDown is called when the user has pressed the mouse button while
		    /// over the GUIElement or Collider.
		    /// </summary>
		    void OnMouseDown ()
		
		    /// <summary>
		    /// OnMouseUp is called when the user has released the mouse button.
		    /// </summary>
		    void OnMouseUp ()
		
		        /// <summary>
		    /// OnMouseDrag is called when the user has clicked on a GUIElement or Collider
		    /// and is still holding down the mouse.
		    /// </summary>
		    void OnMouseDrag ()
		
		       /// <summary>
		    /// Called every frame while the mouse is over the GUIElement or Collider.
		    /// </summary>
		    void OnMouseOver ()
		
		 /// <summary>
		    /// OnMouseUpAsButton is only called when the mouse is released over
		    /// the same GUIElement or Collider as it was pressed.
		    /// </summary>
		    void OnMouseUpAsButton ()
		    //松开鼠标时，仅当鼠标在按下时所在的 Collider 上时，才调用 OnMouseUpAsButton。

2.使用EventTrigger 给ui物体添加EventTrigger，在其中选择需要的事件并添加相应的响应函数

3.通过接口实现拖拽

	using UnityEngine;
	using UnityEngine.EventSystems;
	public class DragByInterface : MonoBehaviour, IPointerDownHandler, IDragHandler, IBeginDragHandler, IEndDragHandler
	{
	    public void OnPointerDown (PointerEventData PointerEventData) { }
	    public void OnBeginDrag (PointerEventData PointerEventData) { }
	    public void OnDrag (PointerEventData PointerEventData) { }
	    public void OnEndDrag (PointerEventData PointerEventData) { }
	}

补充：OnBeginDrag 和 OnEndDrag 依赖于OnDrag。
	pointerEventData中包含一系列信息，包括距上一帧的偏移量，当前拖拽的物体等

	var offset = pointerEventData.delta;
    var dragTarget = pointerEventData.pointerDrag;