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GDC Europe 2014: Unreal Engine 4 for Programmers - Lessons Learned & Things to Come

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A high-level overview of Unreal Engine 4, its game framework, the Slate user interface library, Unreal Motion Graphics, and Editor and Engine extensibility. Presented at GDC Europe in Cologne, Germany.

Also includes bonus slides on concurrency and parallelism features, general tips for programmers and Epic's build and automation infrastructure.

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GDC Europe 2014: Unreal Engine 4 for Programmers - Lessons Learned & Things to Come

  1. 1. Unreal Engine 4 for Programmers Lessons Learned & Things To Come Gerke Max Preussner max.preussner@epicgames.com
  2. 2. Then… • “We ain’t gonna need it” • Fixed, rigid feature set • First Person Shooter centric • Programmer centric • Closed source • Monolithic, aged code base • Secret development schedule • PC & console focused • Millions of $ studio licenses Now… • “You might need it” • Plug-ins and customizable tools • Game type agnostic • Artist & game designer friendly • Public source • Modular code base, largely rewritten • Public feature voting on trello.com • Seamless multi-platform development • $19/month subscription Unreal Engine in 2014
  3. 3. Unreal Engine in 2014
  4. 4. Engine Overview
  5. 5. The Big Picture Directories Configuration Modules Projects Root Directory • /Engine – All code, content & configuration for the Engine • /MyProject – All files for the game project ‘MyProject’ • /Templates – Templates for creating new projects Inside the /Engine and Project Directories • /Binaries – Executables & DLLs for the Engine • /Build – Files needed for building the Engine • /Config – Configuration files • /Content – Shared Engine content • /DerivedDataCache – Cached content data files (Engine only) • /Intermediate – Temporary build products (Engine only) • /Plugins – Shared and project specific plug-ins • /Saved – Autosaves, local configs, screenshots, etc. • /Source – Source code for all the things!
  6. 6. The Big Picture Directories Configuration Modules Projects INI Files • Hold class default properties • Will be loaded into CDOs on startup • Organized in a hierarchy • Higher INIs override lower ones • Organized in sections • Key-value pairs within sections • Important ones exposed in Editor UI • Low-level access with FConfig
  7. 7. The Big Picture Directories Configuration Modules Projects INI Files • Hold class default properties • Will be loaded into CDOs on startup • Organized in a hierarchy • Higher INIs override lower ones • Organized in sections • Key-value pairs within sections • Important ones exposed in Editor UI • Low-level access with FConfig Class Constructor BaseXXX.ini DefaultXXX.ini XXX.ini
  8. 8. Editor & Project Settings
  9. 9. The Big Picture Directories Configuration Modules Projects Modularity Promotes • Reusability • Extensibility • Maintainability • Decoupling • Efficiency Monolithic builds are still possible though!
  10. 10. The Big Picture Directories Configuration Modules Projects Module Types • Developer – Used by Editor & Programs, not Games • Editor – Used by Unreal Editor only • Runtime – Used by Editor, Games & Programs • ThirdParty – External code from other companies • Plugins – Extensions for Editor, Games, or both • Programs – Standalone applications & tools Module Dependency Rules • Runtime modules must not have dependencies to Editor or Developer modules • Plug-in modules must not have dependencies to other plug-ins
  11. 11. The Big Picture Directories Configuration Modules Projects Module Type UnrealEd App Game Runtime √ √ √ ThirdParty √ √ √ Plugins √ √ √ Developer √ √ X Editor √ X X Module usage across different types of applications
  12. 12. The Big Picture Directories Configuration Modules Projects Important Modules for Beginners • Core – Fundamental core types & functions • CoreUObject – Implements the UObject sub-system • Engine – Game classes & engine framework • OnlineSubsystem – Online & social networking features • Slate – Widget library & high-level UI features
  13. 13. The Big Picture Directories Configuration Modules Projects Interesting Modules for Advanced Programmers • DesktopPlatform – Useful APIs for Windows, Mac & Linux • DetailCustomizations – Editor’s Details panel customizations • Launch – Main loop classes & functions • Messaging – Message passing sub-system • Sockets – Network socket implementations • Settings – Editor & Project Settings API • SlateCore – Fundamental UI functionality • TargetPlatform – Platform abstraction layer • UMG – Unreal Motion Graphics implementation • UnrealEd – Unreal Editor main frame & features
  14. 14. The Big Picture Directories Configuration Modules Projects Interesting Modules for Cool Features • Analytics – Collects usage statistics from Editor & games • AssetRegistry – Database for assets in Unreal Editor • GameLiveStreaming – Twitch Streaming • HeadMountedDisplay – HMD Support API (Oculus, etc.) • JsonUtilities & XmlParser – Handle Json & XML files • SourceControl – API for custom source control providers
  15. 15. The Big Picture Directories Configuration Modules Projects Your Game Projects can… • Use Blueprints, C++ Code or both • Contain any number of modules & plug-ins • Be moved around and shared with others Project Templates to Get You Started • Blank (with or without sample content) • First Person Shooter • Side scroller, top-down & puzzle games • Flying & driving games • They all come in Blueprint and C++ flavors • More to come, and make your own!
  16. 16. Project Templates & Samples
  17. 17. Project Packaging & Deployment
  18. 18. Game Framework
  19. 19. Game Framework History UE1 and UE2 • Designed for First Person Shooters (FPS) • UnrealScript game scripting language UE3 • Kismet Visual Scripting added • More modular game classes • But still very FPS centric UE4 • UnrealScript replaced with Blueprints • Game genre agnostic • Lots of sample projects!
  20. 20. UnrealScript vs. C++ vs. Blueprints UnrealScript was: • An object-oriented scripting language • Similar in syntax to C, C++, Java, but also somewhat different • Compiled to virtual machine byte code • Adding interesting features, such as States, Timers, Delegates Blueprints are: • A visual scripting system that is artist and designer friendly • Using the same virtual machine as UnrealScript • Almost as powerful as UnrealScript, and in many ways better C++ has: • Always been part of UE game programming • Tight bi-directional integrations with the virtual machine • Been greatly improved in UE4 to replace UnrealScript for coders C++ Blueprints VM
  21. 21. So What Is The Game Framework? Overview Why Use It? Set Of Foundation Classes • Provide basic structure and functions of your game • You derive from the classes that you need • Fill in the details for your particular game What’s Missing? • Game genre specific implementations • No concept of health and death • No built-in classes for weapons, inventory, etc.
  22. 22. So What Is The Game Framework? Overview Why Use It? Reduced Learning Curve • Hides the low-level details of game engines • Benefit from 20+ years of game developing experience • Many samples and tutorials for solving common tasks High Productivity • Focus on what really matters to you: making your game • Solves many tricky problems in games (movement, input, etc.) • Greatly reduces boilerplate code needed for all games Scalability • Smoothly grow your game & team from prototype to AAA
  23. 23. Fundamental Concepts Actors Components Pawn Character Controller HUD GameMode What is an Actor? • Entity in a game level • Usually contains one or more Actor Components • Supports network replication for multiplayer games Things to know about Actors • Don’t have Location, Rotation (stored in root component) • Created with SpawnActor() method • Must be destroyed explicitly with Destroy() method • Will not be garbage collected during the game
  24. 24. Fundamental Concepts Actors Components Pawn Character Controller HUD GameMode What is an ActorComponent? • Reusable functionality that can be added to an Actor • Contain the most interesting functionality & events Example Components: • Scene Component – Adds transforms and attachments • Primitive Component – Adds collision and rendering • UAudioComponent, UArrowComponent, UInputComponent, ULightComponent, UMeshComponent, UParticleSystemComponent and many more!
  25. 25. Fundamental Concepts Actors Components Pawn Character Controller HUD GameMode PrimiviteComponent Event Examples • Hit – Called when bumping into a wall • Begin/EndOverlap – Walk into or out of a trigger • Begin/EndCursorOver • Clicked/Released • InputTouchBegin/End • Begin/EndTouchOver Also accessible in Blueprints!
  26. 26. Fundamental Concepts Actors Components Pawn Character Controller HUD GameMode What is a Pawn? • An agent in the world • Optionally possessed by a Controller • Usually handles movement and input Things to know about Pawns • Good place to implement health • No movement or input code by default
  27. 27. Fundamental Concepts Actors Components Pawn Character Controller HUD GameMode What is a Character? • Special Pawn that can walk • Comes with useful Components Things to know about Controllers • Handles collision • Client-side movement prediction • Much improvement from UE3
  28. 28. Fundamental Concepts Actors Components Pawn Character Controller HUD GameMode What is a Controller? • A brain that can possess a Pawn • PlayerController: Represents a human player • AIController: Computes AI behavior for Pawns Things to know about Controllers • Possess one Pawn at a time • Can persist after possessed Pawn dies
  29. 29. Fundamental Concepts Actors Components Pawn Character Controller HUD GameMode PlayerController • Interface for players to agents • Handles touches, clicks, keyboard • Showing/hiding mouse cursor • Good place for non-agent code • Menus, voice chat, etc. • Many other useful options
  30. 30. Fundamental Concepts Actors Components Pawn Character Controller HUD GameMode What is a HUD? • Head-Up Display • Responsible for in-game UI Things to know about Controllers • Immediate-mode drawing API • No tools for building HUDs • UMG will provide all the things!
  31. 31. Fundamental Concepts Actors Components Pawn Character Controller HUD GameMode What is a GameMode? • Implements the game rules • Configures default classes for Pawn, Controller, HUD, etc. • Can be accessed from anywhere (GetGameMode()) Things to know about GameModes • Only exists on the server and single player instances! • GameState is used to replicate game state to clients • Default game mode can be set in Project Settings • Per-map overrides in World Settings
  32. 32. Other Important Concepts Input Collision Replication Axes & Actions • Can bind to mouse, keyboard, touch, etc. • Defined in Project Settings Input Processing Order 1. PlayerController 2. Level Blueprint 3. Possessed Pawn
  33. 33. Other Important Concepts Input Collision Replication Various Collision Query Functions • Line traces (ray casts) • Geometry sweeps • Overlap tests Simple Collision • Box, sphere, capsule, convex • Authoring tools in Editor • Used for movement, physics, etc. Complex collision • Actual graphics triangles • Used for weapons, kinematics, etc.
  34. 34. Other Important Concepts Input Collision Replication Transfer game state between Server and Clients • Remote Procedure Calls (RPC) • Data transfer (variables, structs, dynamic arrays) • Editor supports multiplayer PIE testing
  35. 35. Game Framework Flowchart
  36. 36. Slate UI Framework
  37. 37. UE1, UE2 and UE3
  38. 38. Slate Design & Principles Overview Features Concepts Tools Architecture • Written entirely in C++ • Platform agnostic (works on mobile and consoles, too!) • SlateCore module provides low-level functionality • Slate module contains library of common UI widgets • Does not require Engine or Editor modules Current Use Cases • Unreal Editor • Standalone desktop applications • Mobile applications • In-game UI
  39. 39. Slate Design & Principles Overview Features Concepts Tools Styling • Customize the visual appearance of your UI • Images (PNGs and Materials), Fonts, Paddings, etc. • Customizable user-driven layouts Input Handling • Keyboard, mouse, joysticks, touch • Key bindings support Render Agnostic • Supports both Engine renderer and standalone renderers Large Widget Library • Layout primitives, text boxes, buttons, images, menus, dialogs, message boxes, navigation, notifications, dock tabs, list views, sliders, spinners, etc.
  40. 40. Slate Design & Principles Overview Features Concepts Tools Declarative Syntax • Set of macros for declaring widget attributes • Avoids layers of indirection Composition • Compose entire widget hierarchies in a few lines of code • Uses fluent syntax for ease of use • Preferred over widget inheritance • Any child slot can contain any other widget type • Makes it very easy to rearrange UIs in code
  41. 41. // Example custom button (some details omitted) class STextButton : public SCompoundWidget { public: SLATE_BEGIN_ARGS(SMyButton ) { } // The label to display on the button. SLATE_ATTRIBUTE(FText, Text) // Called when the button is clicked. SLATE_EVENT(FOnClicked, OnClicked) SLATE_END_ARGS() // Construct this button void Construct( const FArguments& InArgs ); }; // Button implementation (some details omitted) void STextButton::Construct ( const FArguments& InArgs ) { ChildSlot [ SNew(SButton) .OnClicked(InArgs._OnClicked) [ SNew(STextBlock) .Font(FMyStyle::GetFontStyle(“TextButtonFont")) .Text(InArgs._Text) .ToolTipText(LOCTEXT(“TextButtonToolTip", “Click Me!")) ]; ]; }
  42. 42. Slate Design & Principles Overview Features Concepts Tools Widget Inspector • Visually debug and analyze your UI • Can jump directly to widget code in Visual Studio or XCode UDK Remote • iOS app for simulating touch devices on your PC • Remote server is a plug-in (enabled by default) • Primarily used for game development
  43. 43. Demo
  44. 44. Demo
  45. 45. Going A Little Deeper State Updates Widget Roles Anatomy Attributes Polling instead of Invalidation • Avoids duplicate state data • Exception: Non-trivial data models (use caches instead) • Performance depends on number of visible widgets
  46. 46. Going A Little Deeper State Updates Widget Roles Anatomy Attributes Fundamental Widget Types • SCompoundWidget – Can have nested child widgets • SLeafWidget – Does not contain child widgets • SPanel – Base class for layout panels Special Widgets • SWidget – Root base class for all widgets (do not inherit!) • SNullWidget – Empty default widget User Widgets • More efficient in terms of compile time
  47. 47. Going A Little Deeper State Updates Widget Roles Anatomy Attributes Common Interfaces • Arguments – Widget parameters that do not change • Attributes – Parameters that are polled • Event handlers – Usually named ‘OnSomeEvent’ Common Internals • ComputeDesiredSize() - Calculates widget’s desired size • ArrangeChildren() - Arranges children within allotted area • OnPaint() – Draws the widget
  48. 48. Going A Little Deeper State Updates Widget Roles Anatomy Attributes Common Attributes • Enabled state, Visibility, Hit testability • Tooltip Widget, Tooltip Text, Cursor Style • Horizontal & Vertical Alignment , Padding Attributes Can Be: • Constants, i.e. IsEnabled(false) • Delegate bindings, i.e. IsEnabled(this, &SMyWidget::HandleIsEnabled)
  49. 49. Current In-Game UI Features HUD Canvas VP Widgets Game Menus FCanvas • Low-level C++ API for drawing directly to the screen • Has been part of Unreal Engine for many years • All functions are in FCanvas class • DrawText(), DrawTexture(), DrawTile(), etc. • Use AHUD.Canvas to access the canvas object HHitProxy • Provides basic interaction support for FCanvas • Create one hit proxy per interactive object • Hit proxy ID is sent to GPU for per-pixel hit tests
  50. 50. Current In-Game UI Features HUD Canvas VP Widgets Game Menus UGameViewportClient • Allows usage of Slate widgets inside game view port • Use all features of Slate (except SWindow) • Add/RemoveViewportWidgetContent() Things to keep in mind • All added widgets will be layered on top of each other (SOverlay) • Widgets should use TWeakObjPtr for UObject references
  51. 51. Current In-Game UI Features HUD Canvas VP Widgets Game Menus The Hard Way • Use FCanvas to draw your own menus • Not recommended The Custom Way • Use HUD Widgets to create any menu layout The Lazy Way • Use GameMenuBuilder for paged menus • FGameMenuPage - Single menu page • FGameMenuItem - An option in a menu page • Can be customized and styled • Mostly used for settings screens
  52. 52. Unreal Motion Graphics (UMG)
  53. 53. Unreal Motion Graphics Overview Scripting Upcoming One UI Solution To Rule Them All • Built on top of Slate • Adds real-time animation and transformation to widgets • Integrated with Blueprints • WYSIWYG Editor for artists and designers • No programming required (unless you want to) • Not officially released yet, but already in the code base
  54. 54. Unreal Motion Graphics Overview Scripting Upcoming Adding Behavior to your UI • Designers should not have to write code! • Blueprints allow scripting of UI • You can still use C++ as well, but probably won’t
  55. 55. Unreal Motion Graphics Overview Scripting Upcoming Currently working on: • Materials! • Style assets • 2D Transforms • Special effects • In-world 3D UI • Workflow polish
  56. 56. Arbitrary 2D Transforms
  57. 57. • Attachable UI Actor Components • Injected into render stream • Can intersect with world geometry • Render to texture (optional) • 3D Transformations In-World 3D User Interfaces
  58. 58. Extensibility
  59. 59. Why Do We Want Extensibility? Custom Requirements • Features that are too specific to be included in UE4 • Features that UE4 does not provide out of the box Third Party Technologies • Features owned and maintained by other providers • Scaleform, SpeedTree, CoherentUI, etc. Flexibility & Maintainability • More modular code base • Easier prototyping of new features
  60. 60. How To Extend The Engine General Games Editor Plug-ins UE3: Engine Code Changes • Only accessible to licensees • Required deep understanding of code base • Merging Engine updates was tedious UE4: Extensibility APIs • Modules, plug-ins, C++ interfaces • Native code accessible to everyone • Also supports non-programmers
  61. 61. How To Extend The Engine General Games Editor Plug-ins Blueprint Construction Scripts • Blueprints as macros to create & configure game objects • Activated when an object is created in Editor or game • Check out our excellent tutorials on YouTube!
  62. 62. How To Extend The Engine General Games Editor Plug-ins Details View Customization • Change the appearance of your types in the Details panel • Customize per class, or per property • Inject, modify, replace, or remove property entries Menu Extenders • Inject your own options into the Editor’s main menus Tab Manager • Register your own UI tabs • Allows for adding entirely new tools and features
  63. 63. Default Appearance Detail Customizations
  64. 64. How To Extend The Engine General Games Editor Plug-ins Blutilities • Blueprints for the Editor! • No C++ programming required • Can fire off events that effect the Editor • Currently experimental, but already working • Scheduled for 4.5 (may change)
  65. 65. Procedural Textures, L-Systems, Flipbooks
  66. 66. How To Extend The Engine General Games Editor Plug-ins Overview • Extend the Engine, the Editor, or both • Are completely self contained • Can be enabled and disabled per project • Everything should be a plug-in! Examples • BlankPlugin, UObjectPlugin – Use these to start coding • Perforce & Subversion support for the Editor • Oculus Rift support • Movie players, Twitch Live Streaming, Slate Remote • And many more!
  67. 67. How To Extend The Engine General Games Editor Plug-ins All Plug-ins • Will be loaded automatically on startup (if enabled) • Most not be dependencies of the Engine or other plug-ins Plug-ins with Code • Have their own ‘Source’, ‘Binaries’, ‘Intermediates’ folders • Can have one or more code modules • May declare new UObject and UStruct types • Seldom have Public header files in modules Plug-ins with Content • Have their own ‘Content’ folder • Configuration files (INIs) not supported yet
  68. 68. How To Extend The Engine General Games Editor Plug-ins Descriptor Files (.uplugin) { "FileVersion" : 3, "FriendlyName" : "Paper2D", "Version" : 1, "VersionName" : "1.0", "CreatedBy" : "Epic Games, Inc.", "CreatedByURL" : "http://epicgames.com", "EngineVersion" : "4.2.0", "Description" : "Paper2D.", "Category" : "2D.Helpers", "EnabledByDefault" : true, "Modules" : [ // module definitions omitted ], "CanContainContent" : true }
  69. 69. Vertex Snapping, Ocean Surface, Rollercoaster More on the Wiki!
  70. 70. Questions? Documentation, Tutorials and Help at: • AnswerHub: • Engine Documentation: • Official Forums: • Community Wiki: • YouTube Videos: • Community IRC: Unreal Engine 4 Roadmap • lmgtfy.com/?q=Unreal+engine+Trello+ http://answers.unrealengine.com http://docs.unrealengine.com http://forums.unrealengine.com http://wiki.unrealengine.com http://www.youtube.com/user/UnrealDevelopmentKit #unrealengine on FreeNode
  71. 71. Concurrency & Parallelism
  72. 72. Synchronization Primitives Atomics Locking Signaling Waiting FPlatformAtomics • InterlockedAdd • InterlockedCompareExchange (-Pointer) • InterlockedDecrement (-Increment) • InterlockedExchange (-Pointer) 64- and 128-bit overloads on supported platforms
  73. 73. Synchronization Primitives Atomics Locking Signaling Waiting // Example class FThreadSafeCounter { public: int32 Add( int32 Amount ) { return FPlatformAtomics::InterlockedAdd(&Counter, Amount); } private: volatile int32 Counter; };
  74. 74. Synchronization Primitives Atomics Locking Signaling Waiting Critical Sections • FCriticalSection implements synchronization object • FScopeLock for scope level locking using a critical section • Fast if the lock is not activated Spin Locks • FSpinLock can be locked and unlocked • Sleeps or spins in a loop until unlocked • Default sleep time is 0.1 seconds
  75. 75. Synchronization Primitives Atomics Locking Signaling Waiting Semaphores • Like mutex with signaling mechanism • Only implemented for Windows and hardly used • API will probably change • Use FEvent instead
  76. 76. Synchronization Primitives Atomics Locking Signaling Waiting FEvent • Blocks a thread until triggered or timed out • Frequently used to wake up worker threads FScopedEvent • Wraps an FEvent that blocks on scope exit // Example for scoped events { FScopedEvent Event; DoWorkOnAnotherThread(Event.Get()); // stalls here until other thread triggers Event }
  77. 77. High Level Constructs Containers Helpers General Thread-safety • Most containers (TArray, TMap, etc.) are not thread-safe • Use synchronization primitives in your own code where needed TLockFreePointerList • Lock free, stack based and ABA resistant • Used by Task Graph system TQueue • Uses a linked list under the hood • Lock and contention free for SPSC • Lock free for MPSC TDisruptor (currently not part of UE4) • Lock free MPMC queue using a ring buffer
  78. 78. High Level Constructs Containers Helpers FThreadSafeCounter FThreadSingleton • Singleton that creates an instance per thread FMemStack • Fast, temporary per-thread memory allocation TLockFreeClassAllocator, TLockFreeFixedSizeAllocator • Another fast allocator for instances of T FThreadIdleStats • Measures how often a thread is idle
  79. 79. Parallelization Threads Task Graph Processes Messaging FRunnable • Platform agnostic interface • Implement Init(), Run(), Stop() and Exit() in your sub-class • Launch with FRunnableThread::Create() • FSingleThreadRunnable when multi-threading is disabled FQueuedThreadPool • Carried over from UE3 and still works the same way • Global general purpose thread pool in GThreadPool • Not lock free
  80. 80. Parallelization Threads Task Graph Processes Messaging Game Thread • All game code, Blueprints and UI • UObjects are not thread-safe! Render Thread • Proxy objects for Materials, Primitives, etc. Stats Thread • Engine performance counters
  81. 81. Parallelization Threads Task Graph Processes Messaging Task Based Multi-Threading • Small units of work are pushed to available worker threads • Tasks can have dependencies to each other • Task Graph will figure out order of execution Used by an increasing number of systems • Animation evaluation • Message dispatch and serialization in Messaging system • Object reachability analysis in garbage collector • Render commands in Rendering sub-system • Various tasks in Physics sub-system • Defer execution to a particular thread
  82. 82. Parallelization Threads Task Graph Processes Messaging FPlatformProcess • CreateProc() executes an external program • LaunchURL() launches the default program for a URL • IsProcRunning() checks whether a process is still running • Plus many other utilities for process management FMonitoredProcess • Convenience class for launching and monitoring processes • Event delegates for cancellation, completion and output
  83. 83. Parallelization Threads Task Graph Processes Messaging Unreal Message Bus (UMB) • Zero configuration intra- and inter-process communication • Request-Reply and Publish-Subscribe patterns supported • Messages are simple UStructs Transport Plug-ins • Seamlessly connect processes across machines • Only implemented for UDP right now (prototype)
  84. 84. Upcoming Features Critical sections & events • Better debugging and profiling support Task Graph • Improvements and optimizations UObjects • Thread-safe construction and destruction Parallel Rendering • Implemented inside renderers, not on RHI API level Messaging • UDP v2 (“Hammer”), BLOB attachments, more robust, breakpoints • Named Pipes and other transport plug-ins More lock-free containers
  85. 85. Appendix A: Programming Tips
  86. 86. Getting Started Tools: • Windows: Visual Studio, UnrealVS, Visual Assist X (recommended) • MacOS: XCode For everything else see: https://docs.unrealengine.com/latest/INT/Programming/QuickStart/
  87. 87. Common Blockers Compiling Acronyms Entry Point Compiling is handled through UBT • UBT – Unreal Build Tool • Solution/Projects in Visual Studio and Xcode are a lie!
  88. 88. Common Blockers Compiling Acronyms Entry Point Acronym Soup (and Code Names, too) • UBT – Unreal Build Tool • UHT – Unreal Header Tool • UAT – Unreal Automation Tool • UFE – Unreal Frontend • BP – Blueprint • CDO – Class Default Object • INI – Text Based Configuration File • Cooking – Optimizing game content • Lightmass, Persona, Cascade, Swarm and other tools • etc. pp.
  89. 89. Common Blockers Compiling Acronyms Entry Point I Want To Understand the Engine - Where Is the Main Loop? • LaunchEngineLoop.cpp • It’s really complicated (and everybody hates it) • Please don’t bother with this – start with our tutorials!
  90. 90. Unrealisms Type Names UObjects Basic Types Strings Macros We Use Prefixes for All Types • U – UObject derrived class, i.e. UTexture • A – AActor derrived class, i.e. AGameMode • F – All other classes and structs, i.e. FName, FVector • T – Template, i.e. TArray, TMap, TQueue • I – Interface class, i.e. ITransaction • E – Enumeration type, i.e. ESelectionMode • b – Boolean value, i.e. bEnabled Everything in Unreal is Pascal Case (Upper Camel Case) • Function names and function parameters, too • Even local and loop variables!
  91. 91. Unrealisms Type Names UObjects Basic Types Strings Macros UObjects Work Around Limitations in C++ • Run-time reflection of class properties and functions • Serialization from/to disk and over the network • Garbage collection • Meta data • Also: Blueprint integration Decorate regular C++ Classes with Magic Macros • UCLASS – for class types • USTRUCT – for struct types • UFUNCTION – for class and struct member functions • UPROPERTY – for class and struct variables
  92. 92. Unrealisms Type Names UObjects Basic Types Strings Macros // Example (not actual UE4 code – omitting some more advanced details) USTRUCT() struct FVector2D { UPROPERTY() float X; UPROPERTY() float Y; UFUNCTION () float GetLength() const; };
  93. 93. Unrealisms Type Names UObjects Basic Types Strings Macros Fundamental Types • We don’t use C++ integer types (char, short, int, long, etc.) • Custom typedef’s for ints & strings in GenericPlatform.h (int32, uint32, uint64, TCHAR, ANSICHAR etc.) • Numeric type traits in NumericLimits.h Common Structures • FBox, FColor, FGuid, FVariant, FVector, TBigInt, TRange • And many more in Core module
  94. 94. Unrealisms Type Names UObjects Basic Types Strings Macros Containers • TArray, TSparseArray – Dynamic arrays • TLinkedList, TDoubleLinkedList • TMap – Key-value hash table • TQueue – Lock free FIFO • TSet – Unordered set (without duplicates) • And many more in Core module Delegates • Unicast and multicast delegates • Also thread-safe variants
  95. 95. Unrealisms Type Names UObjects Basic Types Strings Macros Smart Pointers • TSharedPtr, TSharedRef – for regular C++ objects • TWeakPtr – for regular C++ objects • TWeakObjPtr – for UObjects • TAutoPtr, TScopedPtr • TUniquePtr • Similar to boost:: & std:: implementations • Also thread-safe variants
  96. 96. Unrealisms Type Names UObjects Basic Types Strings Macros String Types • FString – Regular string • FText – Localized string, used heavily in Slate UI • FName – String hash, used heavily in UObjects String Literals • TEXT() – Creates a regular(!) string, i.e. TEXT(“Hello”); • LOCTEXT() – Creates a localized string, i.e. LOCTEXT(“Namespace”, “Name”, “Hello”); • NSLOCTEXT() – LOCTEXT with scoped namespace, i.e. NSLOCTEXT(“Name”, “Hello”);
  97. 97. Unrealisms Type Names UObjects Basic Types Strings Macros FNames are case-insensitive! • Can’t rename ‘MisSpelled’ to ‘Misspelled’ in the Editor • Can’t name a property ‘Blast’ if one ‘bLast’ exists
  98. 98. Unrealisms Type Names UObjects Basic Types Strings Macros Logging • UE_LOG, also GLog->Logf() Assertions • check(), checkSlow(), ensure() Localization • LOCTEXT_NAMESPACE, LOCTEXT, etc. Slate (UI Framework) • SLATE_BEGIN_ARGS, SLATE_ATTRIBUTE, etc.
  99. 99. Best Practices Guidelines Principles Coding Guidelines • Posted on http://docs.unrealengine.com • There are some inconsistencies in the code base • If in doubt, follow existing style in current code file Naming Conventions • Choose descriptive names that are as short as possible • Also for local and loop variables! • Avoid your own acronyms
  100. 100. Best Practices Guidelines Principles General Principles • KISS, YAGNI • Composition vs. inheritance • Avoid tight coupling of code and modules • Many trivial instead of few complicated components Design Patterns • SOLID (especially S, O, L and I; DI is not elegant in C++) • Hollywood Principle (especially for Slate & game code) • GOF, EIP Methodologies • DDD, TDD (we support unit tests), AOP
  101. 101. Appendix B: Build Automation
  102. 102. Build Tools UHT UBT UAT Unreal Header Tool (UHT) • Written in C++ • Parses all C++ headers containing UClasses • Generates glue code for all Unreal classes & functions • Generated files stored in Intermediates directory
  103. 103. Build Tools UHT UBT UAT Unreal Build Tool (UBT) • Written in C# (may convert to C++ in the future) • Scans solution directory for modules and plug-ins • Determines all modules that need to be rebuilt • Invokes UHT to parse C++ headers • Creates compiler & linker options from .Build.cs & .Target.cs • Executes platform specific compilers (VisualStudio, LLVM) Other UBT Features • Project file generation (GenerateProjectFiles.bat) • Remote Compilation (iOS, MacOS)
  104. 104. Build Rules
  105. 105. Dependency Graph
  106. 106. Build Tools UHT UBT UAT Unreal Automation Tool (UAT) • Written in C# (may convert to C++ in the future) • Automates repetitive tasks through Automation Scripts • Build, cook, package, deploy and launch projects • Invokes UBT for compilation Other UAT Scripts • Analyze and fix up game content files • Code surgery when updating to new Engine versions • Distributed compilation (XGE) & build system integration • Generate code documentation • Automated Testing of code and content • And many others – you can add your own scripts!
  107. 107. UBT, UHT, UAT Projects
  108. 108. Build Automation SCC CIS Promotion Testing Source Code Control (SCC) • We use Perforce, but you don’t have to • Not just code, but also content and everything else • Also contains compiled binaries from build system (!) • Used to version many other things (Markting, QA, etc.) GitHub Integration • Check-ins are pushed to GitHub Master in near real-time • Script for converting GitHub pull requests to P4 CLs
  109. 109. Build Automation SCC CIS Promotion Testing Continuous Integration System (CIS) • Verifies all check-ins of code and content • Grand Unified Build Process (GUBP) • Thousands of build tasks a day Backend Software • Used custom build server for several years • Experimented with Jenkins, but not scalable enough • Now using Electric Commander • Complex workflows with hundreds of jobs and sub-tasks Build Hardware • Virtualized farm of Windows and MacOS build servers
  110. 110. GUBP
  111. 111. Build Automation SCC CIS Promotion Testing Build Promotion • Selected successful CIS builds are tested by QA • Builds that pass QA will be promoted to stable • Selected stable builds become release candidates • Approved stable builds are released to public
  112. 112. Build Automation SCC CIS Promotion Testing UnrealSync • Tool for artists to fetch the latest promoted build • Aware of P4 branches and projects • Notifies user when new promoted build is available
  113. 113. Build Automation SCC CIS Promotion Testing Automated Testing • Simple and complex tests • Unit tests for C++, content verification • Parallel testing on multiple platforms & devices • Can also run from command line (as a Commandlet) Simple Tests • Single atomic test that can pass or fail • Unit tests for C++, feature tests for content • Examples: Play a map in PIE, verify text wrapping in Slate, etc. Complex Tests • Run same test code on a number of inputs • Examples: Load all maps in the Editor, compile all Blueprints, etc.
  114. 114. // Example for a simple automation test that runs in a game IMPLEMENT_SIMPLE_AUTOMATION_TEST(FSetResTest, "Windows.SetResolution", ATF_Game) bool FSetResTest::RunTest( const FString& Parameters ) { FString MapName = TEXT("AutomationTest"); FEngineAutomationTestUtilities::LoadMap(MapName); int32 ResX = GSystemSettings.ResX; int32 ResY = GSystemSettings.ResY; FString RestoreResolutionString = FString::Printf(TEXT("setres %dx%d"), ResX, ResY); ADD_LATENT_AUTOMATION_COMMAND(FEngineWaitLatentCommand(2.0f)); ADD_LATENT_AUTOMATION_COMMAND(FExecStringLatentCommand(TEXT("setres 640x480"))); ADD_LATENT_AUTOMATION_COMMAND(FEngineWaitLatentCommand(2.0f)); ADD_LATENT_AUTOMATION_COMMAND(FExecStringLatentCommand(RestoreResolutionString)); return true; } Simple Automation Test
  115. 115. Automation Test Demo
  116. 116. Questions? Documentation, Tutorials and Help at: • AnswerHub: • Engine Documentation: • Official Forums: • Community Wiki: • YouTube Videos: • Community IRC: Unreal Engine 4 Roadmap • lmgtfy.com/?q=Unreal+engine+Trello+ http://answers.unrealengine.com http://docs.unrealengine.com http://forums.unrealengine.com http://wiki.unrealengine.com http://www.youtube.com/user/UnrealDevelopmentKit #unrealengine on FreeNode

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