写一个UE5.1 C++ 插件的例子

以下是一个简单的UE5.1 C++插件示例，它创建了一个新的Actor类并将其添加到编辑器的菜单中：

首先，创建一个新的UE5.1插件项目，选择“C++类”模板，并选择“插件”类别。

接下来，添加一个新的Actor类（例如，MyActor）：

// MyActor.h

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "MyActor.generated.h"

UCLASS()
class MYPLUGIN_API AMyActor : public AActor
{
    GENERATED_BODY()

public: 
    AMyActor();

protected:
    virtual void BeginPlay() override;

public: 
    virtual void Tick(float DeltaTime) override;

};

// MyActor.cpp

#include "MyActor.h"

AMyActor::AMyActor()
{
    PrimaryActorTick.bCanEverTick = true;
}

void AMyActor::BeginPlay()
{
    Super::BeginPlay();
}

void AMyActor::Tick(float DeltaTime)
{
    Super::Tick(DeltaTime);
}

接下来，创建一个新的菜单项并添加一个新的Actor：

// MyPlugin.cpp

#include "MyPlugin.h"
#include "MyActor.h"

#define LOCTEXT_NAMESPACE "FMyPluginModule"

void FMyPluginModule::StartupModule()
{
    // 创建菜单项
    FLevelEditorModule& LevelEditorModule = FModuleManager::LoadModuleChecked<FLevelEditorModule>("LevelEditor");
    LevelEditorModule.GetMenuExtensibilityManager()->AddExtender(
        MakeShared<FExtender>()
        ->AddMenuExtension(
            "Actor",
            EExtensionHook::After,
            nullptr,
            FMenuExtensionDelegate::CreateLambda([](FMenuBuilder& MenuBuilder) {
                MenuBuilder.AddMenuEntry(
                    LOCTEXT("MyPlugin", "Add My Actor"),
                    LOCTEXT("MyPluginTooltip", "Adds a new MyActor to the level"),
                    FSlateIcon(),
                    FUIAction(FExecuteAction::CreateLambda([]() {
                        // 创建新的Actor并将其添加到场景中
                        UWorld* World = GEditor->GetEditorWorldContext().World();
                        if (World)
                        {
                            FActorSpawnParameters SpawnParams;
                            SpawnParams.Owner = GEditor->GetEditorWorldContext().World()->GetFirstPlayerController();
                            World->SpawnActor<AMyActor>(AMyActor::StaticClass(), FVector::ZeroVector, FRotator::ZeroRotator, SpawnParams);
                        }
                    }))
                );
            })
        )
    );
}

void FMyPluginModule::ShutdownModule()
{
    // 移除菜单项
    if (FModuleManager::Get().IsModuleLoaded("LevelEditor"))
    {
        FLevelEditorModule& LevelEditorModule = FModuleManager::GetModuleChecked<FLevelEditorModule>("LevelEditor");
        LevelEditorModule.GetMenuExtensibilityManager()->RemoveExtender(MenuExtender);
    }
}

#undef LOCTEXT_NAMESPACE
    
IMPLEMENT_MODULE(FMyPluginModule, MyPlugin)

最后，在插件的.build.cs文件中添加对Engine和LevelEditor模块的依赖：

// MyPlugin.build.cs

using UnrealBuildTool;

public class MyPlugin : ModuleRules
{
    public MyPlugin(ReadOnlyTargetRules Target) : base(Target)
    {
        PCHUsage = PCHUsageMode.UseExplicitOrSharedPCHs;
        
        PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore" });

        PrivateDependencyModuleNames.AddRange(new string[] { "LevelEditor" });
    }
}

现在，在编辑器的Actor菜单中，您应该会看到一个新的“Add My Actor”菜单项，它将添加一个名为MyActor的新Actor到场景中。