原文地址：http://demo.netfoucs.com/u011707076/article/details/44036839

前言

        寒假回家到現在已經有十多天了，這些天回家不是睡就是吃....哎╮(╯▽╰)╭，今天早上一覺醒來，突然得知，UE4免費了，這絕對是個好訊息，前不久我還在糾結怎麼申請校園賬號呢o(╯□╰)o。迫不及待開啟電腦下載了UE引擎的一個類似管理的客戶端，在裡面最醒目的一欄，看到一個令人哭笑不得的導航，如下圖：

  

       EPIC這是要逆天的節奏嗎？不過不管他了，接下來，我們便一同學習一下EPIC提供給我們的這篇從Unity過渡到UE4的經驗之談吧。說明一下，下面我將對這篇文章中的重點內容做翻譯和一些自己的見解，僅供參考，若需更詳細的內容，請訪問官方提供的文件手冊。

那我們就開始吧

The Editor  編輯器

兩個編輯器的佈局如下：

Editing Assets編輯資源

Detail面板就是負責編輯工程資源，類似於Unity裡面的Inspector。

Quick Glossary（Glossary：術語）

 兩個引擎的部分術語對比：

Projects and files工程和檔案

So what are all these directories and files?工程目錄和檔案的具體內容？

Just like Unity projects, Unreal projects always exist in their own directory and have their own project file. You can double-click on .uproject

 files to load your game into the Unreal Editor, or right click for additional options. Project folders have various sub-folders that contain your game's content and source as well as various configuration files and binaries. The most important are the Content and Source sub-folders.就像Untiy的工程一樣，Unreal4的每一個工程都有他們單獨的工程資料夾。可以通過雙擊.uproject 檔案開啟工程，或者通過右鍵檢視更多選項。UE4的工程資料夾包含很多子資料夾和檔案，裡面最重要的是Content和Source 資料夾。

Where do I put my assets?我應該把資源放在那裡？

In UE4, each project has a Content folder. Similar to a Unity project's Assets folder, this is where your game assets are stored. To import assets into your game simply drop files into your project's Content directory and they will be automatically imported and appear in the Content Browser. The assets in the editor will update automatically as you make changes to the files using an external program.UE4的工程資料夾裡面的Content資料夾和Unity的Asset資料夾類似，用來存放遊戲資源。可以通過拖拽的方式，載入資源，對資源進行處理過後，UE4工程將會自動在Content資料夾和ContentBrowser面板中更新資源資訊。

What common file formats are supported?支援的檔案格式

UE4所能支援的一些檔案格式

Asset Type	Supported Formats
3D	.fbx, .obj
Texture	.png, .jpeg, .bmp ,.tga, .dds, .exr, .psd, .hdr
Sound	.wav
Fonts	.ttf, .otf
Videos	.mov, .mp4, .wmv

How is my Scene stored?場景檔案是如何儲存的呢？

In Unity you place GameObjects in a scene and save that as a Scene asset file. Unreal has a Map file that is similar to a Unity Scene. Map files store data about your Level and the objects in it, as well as lighting data and certain level-specific settings.Unity中我們把GameObject放置到場景裡面，並以場景資源的形式儲存。在UE4的工程中Map檔案類似於Unity中的Scene檔案。Map檔案儲存了關卡里面的物體，同樣的包括光照資訊，和關卡本身特定的屬性。

How do I change my project's settings?如何更改工程設定

All project settings can be found from the main menu under Edit / Project Settings. Like Unity's project settings, these allow you to specify information about your project (such as project name and icons), configure game input bindings, and define how the engine behaves when running your project. You can learn more about individual project settings here. Unity also has what's called "player settings". In Unreal, these are "platform settings", and can be found under the "Platforms" category in your project settings.

可以在Edit / Project Settings 工程設定中更改工程的名字啊，圖示啊，設定輸入的繫結資訊啊，定義引擎如何在你的專案中執行，還可以選擇平臺。

Where do my source files go?原始檔是如何執行的

In Unity you're accustomed to placing C# source files in your assets folder.在Unity中，我們習慣於把C#檔案放置在資原始檔夾Assets裡面。

UE4 works differently. For projects that have C++ code, you'll find a "Source" sub-folder under the project directory that has various files, including C++ source (.cpp) and header (.h) files, as well as some build scripts (.Build.cs, .Target.cs) However, Blueprint-only projects won't have a Source folder.但是UE4卻不是這樣的。對於用C++建立的UE4，你將會在遊戲工程資料夾下找到Source子目錄，裡面存放了包含.h,.cpp和各種檔案。然而通過藍圖建立的工程沒有Source資料夾。

The easiest way to get started with C++ in UE4 is to use the editor to Add Code to Project (in the main File menu), or to simply create a new C++ project from scratch from one of the many templates. You can find C++ classes right in the Content Browser and can open the files in Visual Studio or Xcode by double-clicking on their icons.UE4中開始使用C++最簡單的方式是通過編輯器中的 Add Code to Project 命令。或者通過C++工程模板建立的工程只需要在ContentBrowser裡面雙擊程式碼就可以用VS打開了。

From GameObjects to Actors 從GameObjects到Actors

Where Is My GameObject?Unit中GameObject在UE4中如何體現？

In Unity, a GameObject is a "thing" that can be placed in the world. The UE4 equivalent（等價） is an Actor. In the Unreal Editor, you can drag a new Empty Actor into the viewport from the Placement panel:

在Unity中，GameObject是一個可以放置在世界裡面的東西。UE4中的Actor與之等價，在編輯器裡面，我們可以拖放一個空的actor到世界裡面。

You could build a game out of Empty Actors, but UE4 also includes special（特定的） types of Actors with built-in features, such as a Pawn (for players or AI objects), or Character (for animated creatures.) Just like Empty Actors, you can drop these special types of Actors down, then add or customize their properties and components. You'll learn more about it later, but for now try to remember that UE4 has a Gameplay Frameworkthat works with these special Actors.

你可以使用一個空的Actor來建立自己的遊戲，但是UE4內建了很多有特定功能的Actor型別，比如Pawn（是針對players和AI角色），Character（針對有動畫的生物）。和普通的空Actor一樣，我們可以拖拽這些Actors到場景試圖，並且定製他們的屬性和元件。稍後我們將學到這部分內容，但是最重要的是記住，UE4有一個 Gameplay Framework 系統來使用這些Actors工作。

Actors in UE4 are a bit different than GameObjects in Unity. In Unity, GameObject is C# class which you can't directly extend. In UE4, Actor is a C++ class which you can extend and customize using inheritance. We'll talk about this more later on!

UE4中的Actors和Unity中的GameObject有很多不同。Gameob是C#的類，不可以直接擴充套件。而在UE4中，Actors是c++的類，你可以擴充套件並且拖過繼承的方式自定義。稍後我們將繼續學到這部分內容。

Where Are My Components?Unity中的元件在UE4中如何體現？

In Unity, you add components to a GameObject to give it functionality.在Unity中我們可以通過給一個物體元件來給他新增功能。

In UE4, you add components to Actors. After you've dropped an Empty Actor in your level, click the Add Component button (in the Details panel) and choose a component to add. Here, we're creating a torch by dropping an empty actor, then adding a mesh component for the base, followed by a light source and then a particle system to create its flame.空物體--新增元件（mesh、light、particle ）製作火把，看下圖即可

1.拖放空Actor，為其新增StaticMesh元件

  

2.在Mesh元件的層級上，新增點光源元件

3.Mesh上新增例子Particle元件

In Unity, a GameObject hold a flat list of components, but in UE4 an Actor actually contains a hierarchy of components attached to one another. You can see this in the example above, where the Light and Particle are attached to the Mesh. This has some important implications discussed later in Complex Actors and GameObjects.

Unity中一個GameObject的所有元件的關係是平行的，但是在UE4中，一個Actor的元件之間可以存在層次關係。如上面火把的例子中，Light和Particle元件就是依附在Mesh元件上。等下將會在Complex Actors and GameObjects這一節中討論更多重要的概念。

From Unity prefabs to UE4 Blueprint Classes  Unity中的prefabs對應UE4中對應藍圖類

Unity's workflow is based on prefabs. In Unity you build a set of GameObjects with components, then create a prefab from them. You can then place instances of the prefab in your world, or instantiate them at runtime.

Unity的工作流程是基於prefabs的，我們建立一系列具有元件的GameObjects，然後通過他們建立預設，然後我們就可以拖放一個例項到世界中或者在執行的過程中動態生成例項。

UE4's corresponding workflow is based on Blueprint Classes. In UE4, you build an Actor with components, select it, and click the "Blueprint / Add Script" button (in the Details panel). Then, choose a place to save your Blueprint Class, and click "Create Blueprint" to save your new Blueprint Class!

UE4中相對應的工作流程是基於藍圖類的。在UE4中，你可以你可建立一個擁有元件的Actor，選中它，並且在Details面板中點選"Blueprint / Add Script"按鈕，然後選擇一個位置存放藍圖類，最後點選儲存。

Your new Blueprint Classes can be found in the Content Browser. You can double-click to edit them directly, or you can drag and drop them into any level.我們新建立的藍圖類可以再Content Browser面板中找到，我們可以通過雙擊他們直接開啟，並且我們可以把它們拖放到任意的關卡之中。

Where is Script Component and MonoBehaviour? Unity中的指令碼元件和MonoBehaviour中在UE4中如何體現？

In Unity you have Script Components that you drop on GameObjects to add C# scripting. You create a class that inherits from MonoBehaviour to define what that component does.

在Unity中，我們可以給GameObject新增C#指令碼，這個指令碼繼承自MonoBehaviour 來定義元件的功能。

UE4 has something similar. You can create whole new Component classes of your own and drop those onto any Actor. You can create Component classes using either Blueprint Scripting or C++.

So how do you create your own component class in UE4? In the Detail panel's Add Component drop-down, you see you can create new components, or choose existing ones:

UE4中也有一些類似的東西。我們可以建立完全空的元件並且把它們賦給Actor（對比Unity中需繼承MonoBehaviour ）。我們可以通過C++或者藍圖的形式建立元件。在UE4中如何建立自己的獨有的元件呢？答案是在Detail面板中的Add Component 下拉選項中，我們可以建立新的元件或者選擇已有的元件。

In Unity, when creating a new MonoBehaviour you, will be given a skeleton（概要？） class file with a Start() function and an Update() function.

在Unity中，當我們建立一個新的MonoBehaviour 時，會提供給我們一個包含Start（）函式和Update（）函式的類。

In UE4, you will also be given a skeleton class with a InitializeComponent() function and a TickComponent() function, which perform functions similar to Start and Update.

If you create a Blueprint Script Component you will be given these same functions as visual nodes:

在UE4中，系統也將提供給我們兩個函式，他們分別是InitializeComponent() 函式和TickComponent()函式，這兩個函式和Unity中Start（）函式和Update（）函式類似。當我們建立一個藍圖指令碼元件的時候，系統也將提供給我們兩個具有類似功能的視覺化節點。

Scriptable Actor Blueprint Classes 可以編輯的Actor藍圖類

Here is a cool feature in UE4: Your new Actor Blueprint Class can have its own Blueprint Visual Scripting! This allows you to add logic to an entire object, not only an individual component. Combined with inheritance (explained below), this gives you a lot of flexibility when designing your game.UE4中有一個非常酷的功能：你新建的 Actor藍圖類（此處不是元件藍圖類）可以使用藍圖來實現視覺化編輯。這意味著你可以對整個物體新增邏輯，而不僅僅是這個物體中一個特定的元件。這將在你設計自己的遊戲中提供更大的靈活性。

In addition to Blueprint Classes supporting visual scripting, UE4 also supports C++ Classes implemented with code. Here are both, side-by-side.

除了可以視覺化編輯的藍圖指令碼之外，UE4也支援通過程式碼實現功能的C++類。下面給出了三個的對應關係。

Unity c#

1. using UnityEngine;using System.Collections;publicclass MyComponent : MonoBehaviour{    int Count;    // Use this for initialization.    void Start ()    {        Count = 0;    }    // Update is called once per frame.    void Update ()     {        Count = Count + 1;        Debug.Log(Count);    }}

UE4 C++

1. #pragma once#include "GameFramework/Actor.h"#include "MyActor.generated.h"UCLASS()class AMyActor : public AActor{    GENERATED_BODY()    int Count;    // Sets default values for this actor's properties.    AMyActor()     {        // Allows Tick() to be called        PrimaryActorTick.bCanEverTick = true;      }    // Called when the game starts or when spawned.    void BeginPlay()    {        Super::BeginPlay();        Count = 0;    }    // Called every frame.    void Tick(float DeltaSeconds)    {        Super::Tick(DeltaSeconds);        Count = Count + 1;        GLog->Log(FString::FromInt(Count));    }};

UE4藍圖

UE4 Blueprint Classes can be extended。  UE4的藍圖類可以被擴充套件

Unity prefabs and UE4 Blueprint Classes can be instantiated in your game similarly. However, Unity has complications related to nesting prefabs within other prefabs, which limit their role as extensible building blocks.

In UE4, you can create a new Blueprint Class which extends an existing Blueprint Class and augments it with new properties, components, and visual scripting functionality.Untiy的prefabs預設和UE4的藍圖類能夠在你的遊戲中相似的例項化出來。然而，Unity有一些併發機制，他們和預設與預設之間的巢狀相關，這些機制決定或者說限制了他們成為可以在構建時被擴充套件（這兒有點難理解，看下面的例子吧）。

For example, in UE4 you can create a Blueprint Class named Monster（怪物） which implements basic monster functionality such as chasing people. You can then create further Blueprint Classes which extend it, such as Dragon (a type of Monster which adds fire-breathing features), Grue (a Monster which is likely to eat you when it's dark), and for example 8 others. These subclasses of Monster all inherit the basic functionality from Monster, and add new capabilities on top.

例如,在UE4你可以建立一個命名為怪物的藍圖類實現基本功能, 比如追趕人類。然後您可以建立更多的藍圖類來擴充套件它,如龍怪物(對其新增噴火的功能),雪怪(一中可以再黑暗的時候吃掉你的怪物),和其他八種怪物等等。這些怪物的子類都是從一開始建立的有基本功能的怪物類繼承而來,並在其基礎上新增新功能。

In Unity, you would implement this by creating many different GameObject prefabs: one for Dragon, one for Grue, and so on. Now, say you want to add some new functionality to all monsters, such as the ability to speak using your new Speak Component. In Unity, you have to go and update all 10 prefabs to individually copy and paste the new functionality into it.

在Unity中，你的世界通過建立不同的GameObject例項（比如一個作為龍怪，一個作為雪怪等等）來實現這一功能。現在，如果你想給所有的這些怪物新增一些新的功能，比如使用你新建立的Speak元件讓他們有能力說話，在Unity中，你不得不對這十個例項單獨的更新，來為它們新增功能。

In UE4, you can simply modify the Monster Blueprint Class to add this new ability to speak. That's all! Dragon, Grue, and the 8 other subclasses of Monster automatically inherit the new speaking functionality, and you don't need to touch them.

在UE4中，你可以簡單的修改最初的父類怪物藍圖指令碼類新增新的說話功能，僅僅這麼做就夠了，無論是龍怪，雪怪或者其他八種Monster父類的子類都會自動的繼承新的說話的功能，你都不用去單獨的指定它們。

But there's more! Everything we have said here about Blueprint Classes also applies to C++ Classes, and everything is equally true of actors and components. These systems are designed to support large-scale development of extensible functionality, and can scale to projects with 10's or 100's of developers.但是不止如此，我們在這裡說的一切藍圖類也適用於c++類,包括元件和Actor類。這些系統是為了擴充套件而被設計的，包括開發大規模可擴充套件的功能，以及專案開發10人到100人的開發人員人數的擴充套件。（一字一字的翻譯就是：“這些系統是為了用來支援大規模開發可擴充套件的功能,並且可以擴充套件專案10或100的開發人員所設計的”，反正就是這麼一個意思，容易擴充套件）。

Should I use Blueprint Scripting, C++, or both?我應該使用C++，藍圖還是都使用呢？

Blueprint Visual Scripting is ideal for simple in-game logic flow and sequencing of actions. It's a great system for designers, artists, and visually-oriented programmers, because it's easy to access and control in-game objects visually. You can even create small standalone-game using just Blueprints; see the Tappy Chicken sample for a full-fledged example.藍圖這種視覺化的編輯指令碼對於簡單的遊戲邏輯和一些簡單操作的排序是理想的。對於設計者，藝術家和一些以視覺為導向的程式設計師來說，藍圖指令碼是一個非常棒的系統，因為我們可以非常方便通過視覺化的方式實現和控制遊戲物體。甚至，你可以僅僅使用藍圖來建立小的單獨的遊戲。可以參考Tappy Chicken例子來檢視這部分的具體實現。

C++ programming is for larger-scale tasks, such as building gameplay systems, complex AI, and new engine features. If you already have some C++ experience, check out the Introduction to C++ Programming in UE4 page.C++編碼是用來做一些大規模的任務的，比如建立遊戲的框架，複雜的AI和一些新的引擎的功能。如果你有一些C++的經驗，可以之間去檢視 Introduction to C++ Programming in UE4 這一頁。

Most projects will use a mix of Blueprints and C++. Many developers prototype game functionality using Blueprints, because it is so easy and fun, and later move some or all of it to C++ for performance and engineering rigor.大多數的工程會混合使用藍圖指令碼和C++指令碼。許多開發者願意使用藍圖指令碼規範遊戲的功能，因為它非常簡單有趣，然後不就考慮到規範，和效能問題，會把其中的一部分甚至全部移植到C++程式。

Blueprint Classes can extend C++ Classes 藍圖類可以用C++類擴充套件

Much of the magic of UE4 game development comes from the interplay between programmers implementing new features in C++, with designers and artists utilizing them in Blueprints and then asking for more! Here's how a team might structure a UE4-based shooter game implementing pickups using a mix of C++ Classes systems programming, and Blueprint Classes for behaviour and appearance:UE4遊戲開發的魔力來自藍圖指令碼和C++指令碼的共同作用。程式設計師使用C++實現新功能，設計師和藝術家在藍圖指令碼中使用它們，實現新的功能，在需要新功能時再向程式設計師提出。下面是一個例項，展示了一個團隊如何同時使用C++構建一個射擊遊戲的框架，使用藍圖類用來實現具體行為和一些外觀等功能。

Transform Components  Transform元件

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