The Unreal Engine Game Framework: From int main() to BeginPlay

What happens when you start up your Unreal Engine game? This video is a guided tour of the Engine's initialization process: along the way, we'll glimpse the high-level structure of the Engine (modules, game instances, local players, and viewports) and we'll see how all the different parts of the Game Framework (game modes, game states, player controllers, and the like) fit together.

00:00 - Introduction: The game loop
01:13 - Unreal's scary initialization code
02:35 - GuardedMain and FEngineLoop
03:09 - PreInit: loading engine, project, and plugin modules (IModuleInterface, UObject)
05:17 - Init: Creating and starting the Engine (UEngine / UGameEngine)
07:34 - Engine initialization (UGameInstance, UGameViewportClient, ULocalPlayer)
09:24 - LoadMap: Reloading the world from disk (UWorld, ULevel)
11:18 - LoadMap: Bringing the world up for play (AGameModeBase, AGameStateBase, AGameSession)
14:10 - LoadMap: Logging the player into the game (APlayerController, APlayerState, UPlayer / UNetConnection)
15:54 - LoadMap: Restarting the player (APawn, APlayerStart, AController / AAIController)
18:11 - LoadMap: Routing the BeginPlay event (AWorldSettings)
18:43 - Animated callstack summary
21:55 - Base game mode classes (AGameMode, AGameState)
22:36 - Characters and Pawns (ACharacter, UCharacterMovementComponent)
24:02 - Where to specify custom subclasses
25:32 - Delegates and subsystems (UGameInstanceSubsystem, UWorldSubsystem)
26:42 - Conclusion

#UnrealEngine #UE4 #programming

[CinematographyDatabase]

This video must be protected at all costs!

[beanboy]

I really think Epic needs to promote/support/sponsor/hire you to do videos for them. Like Unity did with Brakeys. These are the most in-depth and clearest videos I have seen on UE4 ever. UE4 lacks a lot of good in depth tutorials and videos. Glad you are filling that gap!

[Rubberglass]

My GOODNESS! Been using UE4 for 5 years and this might be the best video I've seen on the core of how the engine works. A+

[tiredsleep]

Dam when the world needed him most, he vanished

[tom.looman]

This is fantastic! Super thorough and well visualized so all these dense concepts are easy to follow along with. A+ this demystifies a lot of the code flow that is difficult to figure out for newbies. (I'll add this video to my written gameplay framework guide, which isn't nearly as detailed as this)

[greyly_]

It's criminal how few views this video has so far. I want to come back in six months and see at least 10k. Epic should promote your videos.

[hasanjamal]

Alex, I hope you return to making Unreal Engine videos like this someday. They truly have changed the trajectory of my career (Student currently). For some people, videos like these make the difference between being overwhelmed by the mountain of knowledge needed for game dev and finding your footing and gradually being able to scale that mountain with confidence. You gave me that and I am sincerely grateful. Thank you.

[KITATUS]

Having spent the past 7-8 years in Unreal Engine 4 - I can say without a doubt, this is the best piece of educational content I have seen for the engine (Sorry Mathew, I still love you!). Keep up the great work!

[ekimr]

I absolutely love your method of explaining Unreal concepts. Short, concise, no "HEY IT'S YA BOI" nonsense that makes me immediately look for another video. Just straightforward and professional. It's a breath of fresh air.

[TrojanLube]

This is a class that has to be presented to game engine developers when they get hired by epic.

[grey]

Alex, I've been watching a ton of your videos the past 6 months or so as I've been learning Unreal for my own projects, and I wanted to share that I just got my first professional job in game dev, in part due to the projects I've built in Unreal. So, thanks for all the help in that process. I've still got a long ways to go in learning, but getting my foot in the door here will allow me to genuinely make a career out of game dev! I'm super excited for the future.

[kumituubi]

This is the best Unreal programming related video ever made, and is still valid in the era of UE5.

[reubs]

You sir have put my videos to shame. Excellent work!

[markyoshikawa]

It felt like I was hired by Epic and you were on boarding me... Thanks so much!

[TrojanLube]

Way so underrated! This deserves more views

[harshamohite]

I've been using UE4 for three years and this video cleared up so much, I can't believe I didn't find something like this sooner. Very thorough, and incredibly high-quality walkthrough of the game loop. Hats off to you!

[Rangerth]

This is by far the best overview of UE4 internals that has ever been done! I never would have found this if it hadn't shown up on Epics site. Thank You!

[yashkhd]

This is one of the rarest video of UE. When dealing with huge source repo like UE you actually need this kind of video to understand overall picture of why things are the way it is. This definitely gives lot of confidence if you plan to update engine. Unfortunately the guy seems busy with other stuff as his channel seems inactive from about an year.

[watcover]

Hi from the Unreal Engine CIS community, thanks for your hard work, it very helpful!

[marckleise]

This is probably the best video I've ever seen about the UE framework and I've looked at hundreds. Epic should use this as a primer for new users and include it in the docs.