UE4之接口

参考：

https://docs.unrealengine.com/zh-CN/Programming/UnrealArchitecture/Reference/Interfaces/index.html

接口的模式比较固定，下面就上我定义的接口

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "UObject/Interface.h"
#include "ReactToTriggerInterface.generated.h"

// This class does not need to be modified.
UINTERFACE(MinimalAPI)
class UReactToTriggerInterface : public UInterface
{
	GENERATED_BODY()
};

/**
 * 
 */
class PLUGINS_ME_API IReactToTriggerInterface
{
	GENERATED_BODY()

	// Add interface functions to this class. This is the class that will be inherited to implement this interface.
public:
	UFUNCTION(BlueprintCallable,BlueprintNativeEvent,Category = "LVCate")
	bool ReactToHighNoon();

	UFUNCTION(BlueprintCallable, BlueprintImplementableEvent, Category = "LVCate")
		bool ReactToMidnight();

	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "LVCate")
	void FuncAsEventNativeEvent();

	UFUNCTION(BlueprintCallable, BlueprintImplementableEvent, Category = "LVCate")
		void FuncAsEventImplementableEvent();

	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "LVCate")
	void FuncAsEventNativeEventWithParam(int value);

	

};

解释一下概率：

BlueprintNativeEvent ：这个关键字，说明这个函数既可以蓝图重写，也可以C++重新

BlueprintImplementableEvent：这个关键字，说明这个函数只能蓝图重新

可以写一个C++类继承接口：

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "ReactToTriggerInterface.h"

#include "ReactToTriggerCppImp.generated.h"


UCLASS()
class PLUGINS_ME_API AReactToTriggerCppImp : public AActor,public IReactToTriggerInterface
{
	GENERATED_BODY()
	
public:	
	// Sets default values for this actor's properties
	AReactToTriggerCppImp();

protected:
	// Called when the game starts or when spawned
	virtual void BeginPlay() override;

public:	
	// Called every frame
	virtual void Tick(float DeltaTime) override;

	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "LVCate")
		bool ReactToHighNoon();
	virtual bool ReactToHighNoon_Implementation() override;

	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "LVCate")
		void FuncAsEventNativeEvent();
	virtual void FuncAsEventNativeEvent_Implementation() override;


	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "LVCate")
		void FuncAsEventNativeEventWithParam(int value);
	virtual void FuncAsEventNativeEventWithParam_Implementation(int value) override;



	UFUNCTION(BlueprintCallable, BlueprintImplementableEvent, Category = "LVCate")
		void FuncAsEventCPPImp();


	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "LVCate")
	void FuncAsEventNativeEventCPPImp();
	void FuncAsEventNativeEventCPPImp_Implementation();

	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "LVCate")
		void FuncAsEventNativeEventWithParamCPPImp(int value);
	void FuncAsEventNativeEventWithParamCPPImp_Implementation(int value);
};

然后在蓝图里面实现一个actor 继承之新写的C++实体类

蓝图实现一个函数可以用如下的脚本：

 再看下面的概念：这里的的函数，是需要在蓝图进行重载的函数

 另外，蓝图调用函数有两种方法，一种是事件方式，一种是函数方式

*****************************************20200821*****************************

今天使用发现了一个大问题：BlueprintImplementableEvent

这个声明的函数不能包含参数

 上面这种形式是不对的，会导致编译出错。

但是如果写成下面的形式，却是OK 的

	UFUNCTION(BlueprintImplementableEvent, Category = "MqttFun")
	void MessageArrivedCallBack(const FString &topic,const FString &message);