UE4 实现真加载Loading Screen/movie player

Setup

首先需要一个自定义的GameInstance;

GameInstance是引擎第一批初始化的对象之一，并且持续整个游戏会话；

创建一个UGameInstance class，这里命名为MyGameInstance

在Project Setting中，找到GameInstance，点+号，创建一个GameInstance Blueprint，然后设置父类为刚建GameInstance；

Movie Player Module

MoviePlayer模块可以与游戏引擎进行对话，并在完成任务时告知游戏引擎，从而使引擎继续运行。
MoviePlayer在其自己的线程中运行，这意味着它可以在引擎停止等待文件加载的同时运行。另外，因为它在后台线程中，所以您必须使用Slate小部件，而不是较新的UMG小部件。

为了使用Movie Player模块，我们必须将其包含在我们的项目中。打开游戏的 Build.CS 文件，然后添加MoviePlayer模块，如下所示：

PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "MoviePlayer" });

code

回到之前创建的GameInstance class

MyGameInstance.h

public:UMyGameInstance();void BeginLoadMap(const FString& MapName);void EndLoadMap(UWorld* LoadedWorld);UPROPERTY()UUserWidget* CurrentWidget;// loading widgetUPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "UMGGame")TSubclassOf<UUserWidget> LoadingWidget;
};

MyGameInstance.cpp主要代码

FLoadingScreenAttributes
https://docs.unrealengine.com/en-US/API/Runtime/MoviePlayer/FLoadingScreenAttributes/index.html

// Fill out your copyright notice in the Description page of Project Settings.#include "MyGameInstance.h"
//#include "Runtime/MoviePlayer/Public/MoviePlayer.h"
#include "MoviePlayer.h"...void UMyGameInstance::Init()
{Super::Init();UE_LOG(LogTemp, Warning, TEXT("---INIT----"));//PreLoadMap，开始加载mapFCoreUObjectDelegates::PreLoadMap.AddUObject(this, &UMyGameInstance::BeginLoadMap);//PostLoadMapWithWorld， 加载完成后FCoreUObjectDelegates::PostLoadMapWithWorld.AddUObject(this, &UMyGameInstance::EndLoadMap);
}void UMyGameInstance::BeginLoadMap(const FString& MapName)
{//if (IsRunningDedicatedServer())//{// return;
//  }FLoadingScreenAttributes LoadingScreen;LoadingScreen.bAutoCompleteWhenLoadingCompletes = false;LoadingScreen.bWaitForManualStop = false; LoadingScreen.bMoviesAreSkippable = false;LoadingScreen.MinimumLoadingScreenDisplayTime = 1.5f; // movie最少播放时间LoadingScreen.WidgetLoadingScreen = FLoadingScreenAttributes::NewTestLoadingScreenWidget(); // movie不存在时，显示的widgetif (LoadingWidget != nullptr){CurrentWidget = CreateWidget<UUserWidget>(this, LoadingWidget);TSharedPtr<SWidget> LoadScreen = CurrentWidget->TakeWidget();LoadingScreen.WidgetLoadingScreen = LoadScreen;}else{UE_LOG(LogTemp, Warning, TEXT("LoadingWidget == nullptr"));}GetMoviePlayer()->SetupLoadingScreen(LoadingScreen);}void UMyGameInstance::EndLoadMap(UWorld* LoadedWorld)
{UE_LOG(LogTemp, Warning, TEXT("end load map"));
}...

打开MyGameInstance_BP ，设置做好的Widget

然后需要点击Launch或Package后才会看到效果