Book Image

Unreal Engine 4.x Scripting with C++ Cookbook - Second Edition

By : John P. Doran, William Sherif, Stephen Whittle
Book Image

Unreal Engine 4.x Scripting with C++ Cookbook - Second Edition

By: John P. Doran, William Sherif, Stephen Whittle

Overview of this book

Unreal Engine 4 (UE4) is a popular and award-winning game engine that powers some of the most popular games. A truly powerful tool for game development, there has never been a better time to use it for both commercial and independent projects. With more than 100 recipes, this book shows how to unleash the power of C++ while developing games with Unreal Engine. This book takes you on a journey to jumpstart your C++ and UE4 development skills. You will start off by setting up UE4 for C++ development and learn how to work with Visual Studio, a popular code editor. You will learn how to create C++ classes and structs the Unreal way. This will be followed by exploring memory management, smart pointers, and debugging your code. You will then learn how to make your own Actors and Components through code and how to handle input and collision events. You will also get exposure to many elements of game development including creating user interfaces, artificial intelligence, and writing code with networked play in mind. You will also learn how to add on to the Unreal Editor itself. With a range of task-oriented recipes, this book provides actionable information about writing code for games with UE4 using C++. By the end of the book, you will be empowered to become a top-notch developer with UE4 using C++ as your scripting language!

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Table of Contents (16 chapters)
Preface
Preface
Who this book is for
What this book covers
To get the most out of this book
Sections
Get in touch
Free Chapter
1
UE4 Development Tools
UE4 Development Tools
Introduction
Technical requirements
Installing Visual Studio
Creating and building your first C++ project in Visual Studio
Changing the code font and color in Visual Studio
Extension – changing the color theme in Visual Studio
Formatting your code (Autocomplete settings) in Visual Studio
Shortcut keys in Visual Studio
Extended mouse usage in Visual Studio
Installing Unreal Engine 4 (UE4)
Creating your first project in UE4
Creating your first level in UE4
UE4 – hot reloading
UE4 – logging with UE_LOG
UE4 – making an FString from FStrings and other variables
2
Creating Classes
Creating Classes
Introduction
Technical requirements
Making a UCLASS – deriving from UObject
Creating a blueprint from your custom UCLASS
Creating a user-editable UPROPERTY
Accessing a UPROPERTY from blueprints
Specifying a UCLASS as the type of a UPROPERTY
Instantiating UObject-derived classes (ConstructObject< > and NewObject< >)
Destroying UObject-derived classes
Creating a USTRUCT
Creating a UENUM( )
3
Memory Management, Smart Pointers, and Debugging
Memory Management, Smart Pointers, and Debugging
Introduction
Technical requirements
Unmanaged memory – using malloc( ) / free( )
Unmanaged memory – using new/delete
Managed memory – using NewObject< > and ConstructObject< >
Managed memory – de-allocating memory
Managed memory – smart pointers (TSharedPtr, TWeakPtr, TAutoPtr) to track an object
Using TScopedPointer to track an object
Unreal's garbage collection system and UPROPERTY( )
Forcing garbage collection
Breakpoints and stepping through code
Finding bugs and using call stacks
Using the profiler to identify hot spots
4
Actors and Components
Actors and Components
Introduction
Technical requirements
Creating a custom Actor in C++
Instantiating an Actor using SpawnActor
Creating a UFUNCTION
Destroying an Actor using Destroy and a Timer
Destroying an Actor after a delay using SetLifeSpan
Implementing the Actor functionality by composition
Loading assets into components using FObjectFinder
Implementing the Actor functionality by inheritance
Attaching components to create a hierarchy
Creating a custom Actor Component
Creating a custom Scene Component
Creating an InventoryComponent for an RPG
Creating an OrbitingMovement Component
Creating a building that spawns units
5
Handling Events and Delegates
Handling Events and Delegates
Introduction
Technical requirements
Handling events that have been implemented via virtual functions
Creating a delegate that is bound to a UFUNCTION
Unregistering a delegate
Creating a delegate that takes input parameters
Passing payload data with a delegate binding
Creating a multicast delegate
Creating a custom Event
Creating a Time of Day handler
Creating a respawning pickup for a First Person Shooter
6
Input and Collision
Input and Collision
Introduction
Technical requirements
Axis Mappings – keyboard, mouse, and gamepad directional input for an FPS character
Axis Mappings – normalized input
Action Mappings – one-button responses for an FPS character
Adding Axis and Action Mappings from C++
Mouse UI input handling
UMG keyboard UI shortcut keys
Collision – letting objects pass through one another using Ignore
Collision – picking up objects using Overlap
Collision – preventing interpenetration using Block
7
Communication Between Classes and Interfaces: Part I
Communication Between Classes and Interfaces: Part I
Introduction
Technical requirements
Creating a UInterface
Implementing a UInterface on an object
Checking if a class implements a UInterface
Casting to a UInterface implemented in native code
Calling native UInterface functions from C++
Inheriting UInterfaces from one another
Overriding UInterface functions in C++
Implementing a simple interaction system with UInterfaces
8
Communication Between Classes and Interfaces: Part II
Communication Between Classes and Interfaces: Part II
Introduction
Technical requirements
Exposing UInterface methods to Blueprint from a native base class
Implementing UInterface functions in Blueprint
Overriding C++ UInterface functions through Blueprints
Calling Blueprint-defined interface functions from C++
9
Integrating C++ and the Unreal Editor: Part I
Integrating C++ and the Unreal Editor: Part I
Introduction
Technical requirements
Using a class or struct as a blueprint variable
Creating classes or structs that can be subclassed in Blueprint
Creating functions that can be called in Blueprint
Creating events that can be implemented in Blueprints
Exposing multi-cast delegates to Blueprint
Creating C++ enums that can be used in Blueprint
Editing class properties in different places in the editor
Making properties accessible in the Blueprint editor graph
Responding to property changed events from the editor
Implementing a native code Construction Script
10
Integrating C++ and the Unreal Editor: Part II
Integrating C++ and the Unreal Editor: Part II
Introduction
Creating a new editor module
Creating new toolbar buttons
Creating new menu entries
Creating a new editor window
Creating a new Asset type
Creating custom context menu entries for Assets
Creating new console commands
Creating a new graph pin visualizer for Blueprint
Inspecting types with custom Details panels
11
Working with UE4 APIs
Working with UE4 APIs
Introduction
Technical requirements
Core/Logging API – defining a custom log category
Core/Logging API – FMessageLog to write messages to the Message Log
Core/Math API – rotation using FRotator
Core/Math API – rotation using FQuat
API – rotation using FRotationMatrix to have one object face another
GameplayAbilities API – triggering an actor's gameplay abilities with game controls
GameplayAbilities API - Implementing stats with UAttributeSet
GameplayAbilities API – implementing buffs with GameplayEffect
GameplayTasks API – making things happen with GameplayTasks
HTTP API – downloading webpages using web requests
HTTP API – displaying downloaded progress
12
Multiplayer Networking in UE4
Multiplayer Networking in UE4
Introduction
Technical requirements
Testing your game as a client and a server simultaneously
Replicating properties over the network
Replicating functions over the network
Handling UI network events
13
AI for Controlling NPCs
AI for Controlling NPCs
Introduction
Technical requirements
Implementing a simple following behavior
Laying down a Navigation Mesh
Creating a Blackboard
Creating a Behavior Tree
Connecting a Behavior Tree to a Character
Creating a BTService
Creating a BTTask
14
User Interfaces - UI and UMG
User Interfaces - UI and UMG
Introduction
Technical requirements
Drawing using Canvas
Adding Slate Widgets to the screen
Creating screen size-aware scaling for the UI
Displaying and hiding a sheet of UMG elements in-game
Attaching function calls to Slate events
Using Data Binding with Unreal Motion Graphics
Controlling widget appearance with Styles
Creating a custom SWidget/UWidget
15
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Instantiating UObject-derived classes (ConstructObject< > and NewObject< >)

Creating class instances in C++ is traditionally done using the keyword new. However, UE4 actually creates instances of its classes internally and requires you to call special factory functions to produce copies of any UCLASS that you want to instantiate. You produce instances of the UE4 blueprints classes, not the C++ class alone. When you create UObject-derived classes, you will need to instantiate them using special UE4 Engine functions.

The factory method allows UE4 to exercise some memory management on the object, controlling what happens to the object when it is deleted. This method allows UE4 to track all references to an object so that on object destruction, all references to the object can be easily unlinked. This ensures that no dangling pointers with references to invalidated memory...

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