1. button从按下到响应的过程
1.先是EventSystem在Update中调用当前输入模块InputModules的Process方法处理所有的鼠标事件，
2.并且输入模块会调用RaycastAll来得到目标信息，
3.通过子物体未挂载IEventSystemHandler，再找父物体方式找到事件实际接收者并执行点击事件
2. button子物体text也勾选了RaycastTarget，为什么是响应button，而不是text
创建一个Button，那这个Button还包含了Text组件，如果text.RaycastTarget勾上
当鼠标点击的时候会调用GetEventHandler函数，
该函数的root参数其实是Text，发现text无IEventSystemHandler组件
但是会查找到它的父物体Button，发现有，然后调用Button的点击事件
核心问题：text缺少IEventSystemHandler
public class Button : Selectable, IPointerClickHandler, ISubmitHandler
public interface IPointerClickHandler : IEventSystemHandler
点击button，先响应text，再查找到button，handlerCount为0，说明无IPointerClickHandler组件
text加上EventTrigger，会响应text的点击事件，不会向上响应button
3. 如何强制让text点击，例如聊天系统点击超链接
text挂脚本实现IPointerClickHandler 接口OnPointerClick
4. 穿透UI点击问题
IsPointerOverGameObject是射线接触到的UI有RaycastTarget
代码语言：javascript复制 public override bool IsPointerOverGameObject(int pointerId)
{
var lastPointer = GetLastPointerEventData(pointerId);
if (lastPointer != null)
return lastPointer.pointerEnter != null;
return false;
}
if (Input.GetMouseButtonDown(0))
{
if (Application.isMobilePlatform && Input.touchCount > 0)
{
for (int i = 0; i < Input.touchCount; i )
{
if (EventSystem.current.IsPointerOverGameObject(Input.GetTouch(i).fingerId))
{
m_isClickUi = true;
break;
}
}
}
else if (EventSystem.current.IsPointerOverGameObject())
{
m_isClickUi = true;
}
}5. EventSystem功能
EventSystem会在Update中调用输入模块PointerInputModule的Process方法来处理输入消息
PointerInputModule会调用EventSystem中的RaycastAll方法进行射线检测
RaycastAll又会调用BastRaycaster的Raycast方法执行具体的射线检测操作，主要是获取被选中的目标信息。
6. 不规则按钮如何响应点击
Polygon Collider 2D
7. 设计建造系统：如何拖动屏幕不响应建筑点击，如何区分是点击建筑还是拖动建筑
物品点击与拖屏
8. GraphicRaycaster.BlockingObjects
不用的时候不勾选2d，3d，在update有性能消耗。默认是none
代码语言：javascript复制if (blockingObjects == BlockingObjects.ThreeD || blockingObjects == BlockingObjects.All)
{
if (ReflectionMethodsCache.Singleton.raycast3D != null)
{
var hits = ReflectionMethodsCache.Singleton.raycast3DAll(ray, distanceToClipPlane, (int)m_BlockingMask);
if (hits.Length > 0)
hitDistance = hits[0].distance;
}
}
if (blockingObjects == BlockingObjects.TwoD || blockingObjects == BlockingObjects.All)
{
if (ReflectionMethodsCache.Singleton.raycast2D != null)
{
var hits = ReflectionMethodsCache.Singleton.getRayIntersectionAll(ray, distanceToClipPlane, (int)m_BlockingMask);
if (hits.Length > 0)
hitDistance = hits[0].distance;
}
}9. 有哪些优化
1.不需要点击事件的可以不勾选RaycastTarget
2.封装点击按钮带参数
代码语言：javascript复制using UnityEngine;
using System.Collections;
using UnityEngine.Events;
using UnityEngine.EventSystems;
public class ClickListener : MonoBehaviour, IPointerClickHandler, IPointerDownHandler,IPointerUpHandler
{
public delegate void VoidDelegate(GameObject go);
public VoidDelegate onClick;
public VoidDelegate onPress;
public VoidDelegate onNewGuideClick;
static public ClickListener Get(GameObject go)
{
ClickListener listener = go.GetComponent<ClickListener>();
if (listener == null) listener = go.AddComponent<ClickListener>();
return listener;
}
public void OnPointerClick(PointerEventData eventData)
{
if (onClick != null)
{
onClick(gameObject);
}
}
bool ispress;
public void OnPointerDown(PointerEventData eventData)
{
ispress = true;
}
public void OnPointerUp(PointerEventData eventData)
{
ispress = false;
}
void Update() {
if (onPress != null && ispress)
onPress(gameObject);
}
}
