AFrameGrabberActor::StartFrameGrab.cpp

bool  AFrameGrabberActor::StartFrameGrab()
{
	TSharedPtr<FSceneViewport> SceneViewport;

	// Get SceneViewport
	// ( quoted from FRemoteSessionHost::OnCreateChannels() )
#if WITH_EDITOR
	if (GIsEditor)
	{
		for (const FWorldContext& Context : GEngine->GetWorldContexts())
		{
			if (Context.WorldType == EWorldType::PIE)
			{
				FSlatePlayInEditorInfo* SlatePlayInEditorSession = GEditor->SlatePlayInEditorMap.Find(Context.ContextHandle);
				if (SlatePlayInEditorSession)
				{
					if (SlatePlayInEditorSession->DestinationSlateViewport.IsValid())
					{
						TSharedPtr<ILevelViewport> DestinationLevelViewport = SlatePlayInEditorSession->DestinationSlateViewport.Pin();
						SceneViewport = DestinationLevelViewport->GetSharedActiveViewport();
					}
					else if (SlatePlayInEditorSession->SlatePlayInEditorWindowViewport.IsValid())
					{
						SceneViewport = SlatePlayInEditorSession->SlatePlayInEditorWindowViewport;
					}
				}
			}
		}
	}
	else
#endif
	{
		UGameEngine* GameEngine = Cast<UGameEngine>(GEngine);
		SceneViewport = GameEngine->SceneViewport;
	}
	if (!SceneViewport.IsValid())
	{
		return false;
	}

	// Setup Texture
	if (!CaptureFrameTexture)
	{
		CaptureFrameTexture = UTexture2D::CreateTransient(SceneViewport.Get()->GetSize().X, SceneViewport.Get()->GetSize().Y, PF_B8G8R8A8);
		CaptureFrameTexture->UpdateResource();

		MaterialInstanceDynamic->SetTextureParameterValue(FName("Texture"), CaptureFrameTexture);
	}
	
	// Capture Start
	ReleaseFrameGrabber();
	FrameGrabber = MakeShareable(new FFrameGrabber(SceneViewport.ToSharedRef(), SceneViewport->GetSize()));
	FrameGrabber->StartCapturingFrames();

	return true;
}