UE4尝试用C++创建蓝图并添加变量

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目标

使用C++创建蓝图资源，并尝试给蓝图添加变量。
（引擎版本4.26）

步骤0. 创建测试用插件

使用编辑器工具栏按钮为模板创建插件。

使用这个模板的理由是它初始会有个按钮，可以用来触发操作：

之后将会替换这其中所触发的操作。

步骤1. 创建蓝图

对KismetEditorUtilities.h进行include，因为创建蓝图需要用到其中的方法：

#include"Kismet2/KismetEditorUtilities.h"

对AssetRegistryModule.h进行include，因为需要通知蓝图资源的创建。

#include"AssetRegistryModule.h"

随后，将按钮触发的操作替换为：

//资源名：
const FString AssetName = "YaksueTestBP";
//package路径名：
const FString PackageName = "/Game/" + AssetName;//创建Package
UPackage * Package = CreatePackage(nullptr, *PackageName);//创建蓝图
UBlueprint* NewBlueprint = FKismetEditorUtilities::CreateBlueprint(AActor::StaticClass(),						//ParentClass					the parent class of the new blueprintPackage,									//Outer							the outer object of the new blueprintFName(*AssetName),							//NewBPName						the name of the new blueprintEBlueprintType::BPTYPE_Normal,				//BlueprintType					the type of the new blueprint (normal, const, etc)UBlueprint::StaticClass(),					//BlueprintClassType			the actual class of the blueprint asset (UBlueprint or a derived type)UBlueprintGeneratedClass::StaticClass(),	//BlueprintGeneratedClassType	the actual generated class of the blueprint asset (UBlueprintGeneratedClass or a derived type)FName("YaksueTestContext"));				//CallingContext				the name of the calling method or module used to identify creation methods to engine analytics/usage stats (default None will be ignored)//通知这个蓝图资源创建了
FAssetRegistryModule::AssetCreated(NewBlueprint);//编译蓝图
FKismetEditorUtilities::CompileBlueprint(NewBlueprint);

效果：点击按钮后会创建一个空白的蓝图：

步骤2. 为蓝图添加变量

关于“添加变量”这个功能，我翻阅代码找到了 FBlueprintEditorUtils::AddMemberVariable 接口。

通过字符串搜索，我找到了一处使用范例，在\UE_4.26\Engine\Plugins\Tests\EditorTests\Source\EditorTests\Private\UnrealEd\EditorBuildPromotionTests.cpp：

关于变量的类型，通过UEdGraphSchema_K2::PC_String指定为“字符串”。

---

需要添加BlueprintGraph这个模块到TestCppBP.Build.cs的PrivateDependencyModuleNames中。因为UEdGraphSchema_K2::PC_String等其他的类型实际是个名字，为 static：

其值在EdGraphSchema_K2.cpp中指定：

如果不添加BlueprintGraph这个模块，UEdGraphSchema_K2::PC_String等的值无法知道。

---

仿照范例添加字符串变量：

FEdGraphPinType StringPinType(UEdGraphSchema_K2::PC_String,		//PinCategory				Category of pin typeNAME_None,							//PinSubCategory			Sub-category of pin typenullptr,							//PinSubCategoryObject		Sub-category objectEPinContainerType::None,			//ContainerTypefalse,								//bIsReference				Whether or not this pin is a value passed by reference or notFEdGraphTerminalType());			//PinValueType				Data used to determine value types when bIsMap is trueFBlueprintEditorUtils::AddMemberVariable(NewBlueprint, "TestString", StringPinType);

效果，成功添加：

最终代码

...
#include"Actor.h"
#include"Kismet2/KismetEditorUtilities.h"
#include"Kismet2/BlueprintEditorUtils.h"
#include"AssetRegistryModule.h"
...
void FTestCppBPModule::PluginButtonClicked()
{//资源名：const FString AssetName = "YaksueTestBP";//package路径名：const FString PackageName = "/Game/" + AssetName;//创建PackageUPackage * Package = CreatePackage(nullptr, *PackageName);//创建蓝图UBlueprint* NewBlueprint = FKismetEditorUtilities::CreateBlueprint(AActor::StaticClass(),						//ParentClass					the parent class of the new blueprintPackage,									//Outer							the outer object of the new blueprintFName(*AssetName),							//NewBPName						the name of the new blueprintEBlueprintType::BPTYPE_Normal,				//BlueprintType					the type of the new blueprint (normal, const, etc)UBlueprint::StaticClass(),					//BlueprintClassType			the actual class of the blueprint asset (UBlueprint or a derived type)UBlueprintGeneratedClass::StaticClass(),	//BlueprintGeneratedClassType	the actual generated class of the blueprint asset (UBlueprintGeneratedClass or a derived type)FName("YaksueTestContext"));				//CallingContext				the name of the calling method or module used to identify creation methods to engine analytics/usage stats (default None will be ignored)//通知这个蓝图资源创建了FAssetRegistryModule::AssetCreated(NewBlueprint);//添加一个字符串类型的变量{FEdGraphPinType StringPinType(UEdGraphSchema_K2::PC_String,		//PinCategory				Category of pin typeNAME_None,							//PinSubCategory			Sub-category of pin typenullptr,							//PinSubCategoryObject		Sub-category objectEPinContainerType::None,			//ContainerTypefalse,								//bIsReference				Whether or not this pin is a value passed by reference or notFEdGraphTerminalType());			//PinValueType				Data used to determine value types when bIsMap is trueFBlueprintEditorUtils::AddMemberVariable(NewBlueprint, "TestString", StringPinType);}//编译蓝图FKismetEditorUtilities::CompileBlueprint(NewBlueprint);
}
...

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