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UE(4):UPROPERTY宏、UFUNCTION宏

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UPROPERTY宏、属性说明符和元数据说明符

UPROPERTY宏

UPROPERTY宏：把C++里的变量暴露给蓝图，实现在蓝图中访问C++变量，达到C++和蓝图通信的效果

属性说明符

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// 仅在类默认设置可见
UPROPERTY(VisibleDefaultsOnly)	// 虚幻C++生成反射数据，在蓝图中可以找到相应的变量
    int32 VisibleDefaultsOnlyInt;
// 仅在实例化细节面板可见
UPROPERTY(VisibleInstanceOnly)	
    FString VisibleInstanceOnlyString;
// 类默认设置和实例化细节面板都可见
UPROPERTY(VisibleAnywhere)
    FVector VisibleAnywhereVector;
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// 仅在类默认设置里面编辑
UPROPERTY(EditDefaultsOnly)
    int32 EditDefaultsOnly;
// 仅在实例化细节面板编辑
UPROPERTY(EditInstanceOnly)
    FString EditInstanceOnlyString;
// 类默认设置和实例化细节面板都编辑
UPROPERTY(EditAnywhere)
    FVector EditAnywhereVector;
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// 仅在蓝图中可读
UPROPERTY(EditAnywhere,BlueprintReadOnly)
    int32 BlueprintReadOnlyInt;
// 在蓝图中可读可写，即可以获取和设置变量
UPROPERTY(EditAnywhere, BlueprintReadWrite)
    int32 BlueprintReadWriteInt;
// BlueprintReadOnlyInt只能获取，BlueprintReadWriteInt既可获取又能设置

image-20240820173600330

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// Category属性目录
UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "MyIntValue")
    int32 Value1;
UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "MyIntValue|MySubIntValue")
    int32 Value2;
// 为变量创建目录

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元数据说明符

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// meta元数据说明符
// DisPlayName别名：将变量用另一个别名替换
// MyValue3被MyValue3DisplayName替换
UPROPERTY(EditAnywhere, BlueprintReadWrite, meta = (DisPlayName = "MyValue3DisplayName"))
	int32 MyValue3;

image-20240820175451727

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// EditCondition条件控制编辑
// 只有当Controller为真时，Value3才可编辑
UPROPERTY(EditAnywhere, BlueprintReadWrite, meta = (DisPlayName = "Controller"))
	bool isController;
UPROPERTY(EditAnywhere, BlueprintReadWrite, meta = (EditCondition = "isController"))
	float Value3;

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// Tooltip解释说明我们的变量
UPROPERTY(EditAnywhere, BlueprintReadWrite, meta = (ToolTip = "isControllerTrue"))
	bool isTrue;

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UFUNCTION宏、属性说明符和元数据说明符

UFUNCTION宏：生成函数的反射数据，将函数暴露给蓝图，实现函数和蓝图之间的通信

属性说明符

BlueprintCallable：暴露我们的函数在蓝图中可调用

BlueprintPure：纯虚函数的定义

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// 暴露我们的函数在蓝图中可调用
UFUNCTION(BlueprintCallable, Category = "My Function")
	void PrintF1();
// 纯虚函数的定义BlueprintPure
UFUNCTION(BlueprintCallable, BlueprintPure, Category = "My Function")
	bool PrintF2();

有返回值vs无返回值

  • 有返回值的是一个函数，无返回值的是一个事件

image-20240820205201302image-20240820205206787

BlueprintImplementableEvent：在C++中声明，不能定义，蓝图可重载

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// BlueprintImplementableEvent:在C++中声明，不能定义，蓝图可重载
UFUNCTION(BlueprintImplementableEvent)
	void Test1();
UFUNCTION(BlueprintImplementableEvent)
	int Test2();
UFUNCTION(BlueprintImplementableEvent)
	void Test3(const FString &MyString);
UFUNCTION(BlueprintImplementableEvent)
	int Test4(const FString& MyString);

BlueprintNativeEvent：在C++中声明和实现，蓝图可重载或者不重载

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// BlueprintNativeEvent:在C++中声明和实现，蓝图可重载或者不重载
UFUNCTION(BlueprintNativeEvent)
	void TestA();
UFUNCTION(BlueprintNativeEvent)
	int TestB();
UFUNCTION(BlueprintNativeEvent)
	void TestC(const FString &mystring);
UFUNCTION(BlueprintNativeEvent)
	int TestD(const FString& mystring);
// 实现时函数名=原函数名+_Implementation
void AMyPawn::TestA_Implementation()
{
	GEngine->AddOnScreenDebugMessage(-1, 5.0f, FColor::Red, TEXT("TestA"));
}

示例：在 BeginPlay 中调用 TestA， 在蓝图中重载 TestA

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运行结果：

image-20240821124837582

元数据说明符

DisplayName：为函数起别名

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// 元数据说明符meta
UFUNCTION(BlueprintCallable, Category = "My Function", meta = (DisplayName = "MyPrintTest"))
	void PrintTest();

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