UE4 创建一个actor，具有截图保存功能（C++实现）

可以通过以下步骤在UE4中创建一个Actor并实现截图保存功能：

1. 创建一个继承自Actor的C++类，例如命名为MyActor。

2. 在MyActor.h中添加以下头文件：

#include "Engine/TextureRenderTarget2D.h"
#include "Engine/Texture2D.h"

3. 声明一个TextureRenderTarget2D成员变量和一个Texture2D成员变量：

UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Screenshot")
UTextureRenderTarget2D* ScreenshotRenderTarget;

UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Screenshot")
UTexture2D* ScreenshotTexture;

4. 在MyActor.cpp中重写BeginPlay()函数，创建RenderTarget和Texture：

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

    ScreenshotRenderTarget = UGameplayStatics::CreateRenderTarget2D(GetWorld(), 1920, 1080);
    ScreenshotTexture = UTexture2D::CreateTransient(1920, 1080);
}

5. 在MyActor.cpp中添加一个截图函数：

void AMyActor::TakeScreenshot()
{
    if (ScreenshotRenderTarget != nullptr && ScreenshotTexture != nullptr)
    {
        FTextureRenderTargetResource* RenderTargetResource = ScreenshotRenderTarget->GameThread_GetRenderTargetResource();
        FReadSurfaceDataFlags ReadPixelFlags(RCM_UNorm);
        ReadPixelFlags.SetLinearToGamma(true);
        TArray<FColor> OutBMP;
        RHIReadSurfaceData(RenderTargetResource->GetRenderTargetTexture(), FIntRect(0, 0, ScreenshotRenderTarget->SizeX, ScreenshotRenderTarget->SizeY), OutBMP, ReadPixelFlags);

        ScreenshotTexture->PlatformData->Mips[0].BulkData.Lock(LOCK_READ_WRITE);
        uint8* TextureData = (uint8*)ScreenshotTexture->PlatformData->Mips[0].BulkData.Realloc(OutBMP.Num() * 4);
        for (int32 i = 0; i < OutBMP.Num(); i++)
        {
            TextureData[i * 4 + 0] = OutBMP[i].B;
            TextureData[i * 4 + 1] = OutBMP[i].G;
            TextureData[i * 4 + 2] = OutBMP[i].R;
            TextureData[i * 4 + 3] = OutBMP[i].A;
        }
        ScreenshotTexture->PlatformData->Mips[0].BulkData.Unlock();
        ScreenshotTexture->UpdateResource();
        FString FileName = FPaths::ProjectSavedDir() + TEXT("Screenshots/MyScreenshot.png");
        FFileHelper::SaveArrayToFile(ScreenshotTexture->PlatformData->Mips[0].BulkData, *FileName);
    }
}

6. 在MyActor.cpp中添加一个函数，用于在按下某个按键时调用截图函数：

void AMyActor::CaptureScreenshot()
{
    TakeScreenshot();
}

7. 在MyActor的Blueprint中添加一个InputComponent，将某个按键与CaptureScreenshot函数绑定即可。

完成以上步骤后，你就可以在UE4中创建一个Actor，并在其中实现截图保存功能了。