Umar Bradshaw - Unreal Engine 5 Game Programming Design Patterns in C++, Java, C#, and Blueprints

Unreal Engine 5 Game Programming Design Patterns in C++, Java, C#, and BlueprintsSonicworkflow

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To Lilly, Dwayne, and MadisonContentsIntroduction

Hi, and welcome to Unreal Engine 5 Game Programming Design Patterns in C++, Java, C#, and Blueprints . I wrote this book because I struggled with learning Unreal Engines Blueprints visual scripting system. I felt like everything I did in Blueprints was sort of a hack. You see, I knew how to program in many traditional programming languages and possessed a masters in software engineering from an ABET accredited institution. In fact, my skill level was intermediate to advanced Java, C++, C#, and JavaScript. However, these languages are very mature and one can just Google to find the solution to almost any question. This is FAR from the case when it comes to visual scripting!

Visual scripting is not novel. Unreal Engine is not the first tool to implement this kind of programming, nor will it be the last... I see you Unity! There will be a proliferation in learning resources regarding visual scripting as Unreal and Unity become more popular. This book seeks to be the first one discussing design patterns. We will be using Unreal Engine Editor version 5.0 and we will use 4.2x.x for the Java and C# examples. The 4.2x.x blueprints work in UE5 identically.

How to Read this Book

Blueprint files should be obtained first for maximal understanding from sonicworkflow.com . It is advisable to start with the Builder Pattern section. This section goes into details other sections will avoid for the sake of redundancy reduction. Therefore, if the reader skips this section they may be lost if they are not hardened blueprint and design pattern experts. One should find the remaining sections much clearer once the Builder Pattern section is read and understood.

Errors

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What is in this Book?

This book is a crosswalk from traditional code to visual scripting. This book is about reconstructing traditional and widely used design patterns in a visual scripting environment. The visual scripting environment is Unreal Engines Blueprints. We will discuss and implement design patterns to solve some of the most common problems in programming. You will not need to read much of the background material on the design patterns if you are an experienced coder. Chances are, you probably have used many of these patterns previously. Do not fret If you are not a coder. If you are familiar with Blueprints, then you can, and should implement design patterns into your workflow when necessary.

C++, Java, and C# equivalent code is provided for each design pattern discussed. Additionally, there is an accompanying UML diagram for each design pattern of the Java code implementation. We follow the code in blueprints as close as possible. Some of you may be thinking, Hey Umar, why would you use Java and C# when Unreals main coding language is C++. I have nothing against C++. I chose to add Java and C# for a few reasons.

What is Not in this Book?

This book is not about how to start using blueprints from scratch. This is not a zero to hero blueprints quest. You will struggle if you do not have a decent familiarity with blueprints. Plainly, this is not a beginners book . Comparatively, one would not attempt to learn C++ from the Gang of Fours design patterns book. Since I brought it up, Design Patterns, Elements of Reusable Object-Oriented Software is the granddaddy of design patterns references. It is basically the authority on the topic of design patterns. You would be hard pressed to find a reputable source on the topic not borrowing ideas from that book. The Gang of Four, aka GoF, refer to the books four authors.

This book is not a treatise on design patterns. The Gang of Fours book is a must read for further depth and understanding of the topic.

This book is not a level design, artificial intelligence, user interface, animation etc. blueprint tutorial. The example implementations are trivial, like printing a string to the screen/viewport trivial. To that end, focus is set on the design patterns themselves, not bells and whistles in Unreal Engine. This is done with great care and consideration to reduce obsolescence. Unreal Engine changes so frequently that a large portion of written publications are all but obsolete by the time they are published.

Also, this is not a best practices book. Please do not use this book as a reference for blueprint best practices. This book tries to follow the equivalent code as much as possible. To that end, we may diverge from blueprint best practices to mimic as close as possible what is written in code. Epic has taken great pains to abstract away common programming tasks in blueprints. I encourage you to learn the official API, because often theres a node for that.

There are many ways to skin a cat, so to speak. The implementation of each Design pattern may possess alternative and perhaps even better blueprint implementations. This book only provides one example of many.

Blueprint Weirdness and Unconventional Methodologies

Blueprint Interfaces

Blueprint scripting in Unreal has some different ways of implementing traditional programming constructs. The most confusing topic, especially coming from a software engineering background is the blueprint interface. The blueprint interface is widely cited as being a communication tool. I nearly had a panic attack when I heard Epics staff say this in a live training stream. The same communication idea is echoed in the documentation. I cannot tell you how many times I yelled at my computer screen while reading documentation on blueprint interfaces. I would yell, No, interfaces have nothing to do with communication! All interfaces do is define a guaranteed behavioral contract for objects which implement them. Yet, Im wrong. One must let go of their traditional understanding of an interface. One must embrace the blueprint interface communication deal. Before you think Im bashing Unreal, let me provide you with a great excerpt on blueprint interfaces from their documentation:

A Blueprint Interface is a collection of one or more functions - name only, no implementation - that can be added to other Blueprints. Any Blueprint that has the Interface added is guaranteed to have those functions. This is essentially like the concept of an interface in general programming

-https://docs.unrealengine.com/en-us/Engine/Blueprints/UserGuide/Types/Interface

Cannot spawn in construction script

The heading is self-explanatory. Why this poses a challenge when trying to construct objects in the constructor is not intuitive. The construction script is executed before the game runs in the editor. We cannot spawn objects without a world to spawn into. The workaround was using the Add Child Actor Component node. There may be a better way, but this works so far. We shy away from the extensive use of the construction script in the C++ blueprints but make extensive use of it for the Java and C# implementation.

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