How does a custom game engine work? // Code Walkthrough
Вставка
- Опубліковано 5 чер 2024
- big nerd explains his C++ game engine and says "um" a lot.
SEE THE MAIN VIDEO: • 3 Months of Game Progr...
TWITTER: / jdah__
PATREON: / jdah
GITHUB: github.com/jdah
EDITOR: NeoVim
VIMRC: gist.github.com/jdah/4b4d98c2...
THEME: gruvbox
RESOURCES:
cppreference.com/
learnopengl.com
opengl-tutorial.org
shadertoy.com
stackoverflow.com
0:00 Intro
1:35 Globals
7:22 Project Structure
8:35 Components and Managers
18:35 Usage Demo
23:13 Events
26:15 Level Data
27:20 Renderer
31:56 Resource Management
39:30 Palettization/Compositing
44:00 UI
45:44 Memory Allocation
49:00 Utils
51:00 Outro - Наука та технологія
thank you for making this video! a lot of youtubers just make a devlog and skim over the details, which is a shame because i love seeing how things are implemented and what solutions they found to various problems
You making game engine?
@@glassystudioI am, and videos like this are few and far between.
53 minutes of C++ implementation for real problems. Looking forward to watching this
Agreed
did you finish watching it?
Thank you! Very nice, casual, and descriptive. I would say, these kinda of review/informal kind of chat after a main video is great! I understand if they are exhaustive or more work. But I like the deeper off the cuff dive after the more entertaining and thought out dev blogs.
they're actually much much much easier than the main video, not much prep/work at all - so good to know that you appreciate them!
@@jdh Hi there, may I ask what software (and which version) were you using in this video of yours? I'm new so I apologise in advance.
@@neocell710 He is using vim
@@grimtermite191 Thanks.👍👍
@@neocell710 he’s actually using nvim (neo vim) it’s like a version of vim but better
Im glad you made this video because I've been working on my own game engine in c++ for a while after being inspired by some of your videos a long time ago and I think it will be quite useful to compare my code structure to yours and maybe this will help me on some problems that im currently having! Keep up the good work!!
I was legit asking myself how some of your code would look during/after watching the summary video. It's been about 5 years since I last programmed C/C++, very interesting to see some of the modern stuff.
Your codebase looks well designed. I got really inspired by this.
Thank you. It's a great video format.
this is way more interesting than"ok so I put this line of code in to make this happen" then dont explain it at all. As a hobbist game developer I really appreciate this and thank you. I hope to see more code walkthroughs like this pop up.
Dude, you're building your own computers and game engines... I gotta get my shit together and do something myself too. Thank you for inspiring me and keep up the amazing work!
not only he's an excellent programmer, dude is fu*king handsome too.
"you're doing great, son!"
Damn true
This just popped up on my feed. As someone who writes engines in C, I basically live by the "You can take a C programmer out of C, but not the C out of a C programmer" bit 🤣. Interesting stuff.
Really cool video! I love long talky videos, your streams were also great so I'm excited that you are considering doing more of those
This is utterly amazing! I've already learned a lot from the first watchthrough, like macros, using ECS & OOP, and about memory allocation.
I will definitely be rewatching this as I work on my own C++ engine, and I'm so glad I discovered you!!!
Another video? We are BLESSED
Ever since you uploaded the Minecraft video where you start on this engine, I’ve been working on my own engine in rust. Every time you upload I’m just amazed at the progress you make.
Anyway, thanks for the great video, keep it up!
Not sure if you've read any of it, but the devs of the game Factorio have an amazing dev blog that they release every friday where they've taken deep dives into problems that they're facing, and how they go about implementing them. Obv it'd be a lot of work but I think it'd be cool to see a more detailed narrow focus on how you fixed specific things as you go.
Loving the development updates btw, it's been so cool to see this channel evolve from the first minecraft video
I sense that this video would be useful if I knew c++
Very exciting format! Please do more of this stuff
Just started learning C++ and managed to split some strings with help in around 6 hours. I think I make a similar project now. :)
Jokes aside, i really want to use c++ for some gamedev and maybe make my engine some day so this video just came around the right time.
Thanks for the entertainment in these past few years, keep it up legend.
Dude I have been waiting for this to happen, this is so sick and I love the "lecture style." Man I love the DIY aspect of making your own game, ON YOUR OWN ENGINE. Lmao, keep it up man.
Edit: I also much prefer the new font, it is less minecraft like.
Edit 2: Do you think this will ever be available on steam? (Or on the git hub, but I don't think anyone would be angry if you monetized it and sold it on steam)
Very cool! I'm not even close to a point where I could understand any of this, but it was still very fun to listen along and try to understand at least a tiny bit :> You have a soothing voice to listen to!
Always cool to see how other people do things! I love your "macro garbage" for tracking types. I was discouraged from using macros early-on and I never really went back to find the places where it makes sense to use them, i think this looks like a solid example.
I was just thinking yesterday how nice would a video like this be, and voilá! Thank you for the video, and I hope you do more of these detailed videos.
This was super cool! I hope you make more of these types of videos
Thank you for the code walkthrough! I really enjoyed your description of your work. I was just wondering how you do the searches with your neovim config? Other than that, I really enjoy your content and it’s super inspiring!
Great vid man! the inheritance-based design definitely has its uses, but I also favor composition for games where you have a lot of similar entities with slightly different behaviors.
Always excited for a jdh video!!
Thank you for going through this!! Really great to see how an engine is architected. I'm planning to build an engine in JavaScript based on BabylonJS. So much of the design patterns can still apply. Code would of course be completely different. But you really used some good and interesting design patterns here. I can see how you followed the factory pattern for your entity components. Good stuff!! Thanks again!! :-D
If you dont mind me asking, why javascript as a languge for the engine?
@@gachastorys5129 Because I'm already using it to build an enterprise scale automation platform and eco-system of toolkits for building business applications and I realized that my architecture is adaptable enough to be reused as a toolkit and framework for building a game engine based on the existing BabylonJS rendering engine. BabylonJS was the only engine that I could find that I knew I could natively support multi-camera, multi-view, multi-monitor support without doing some weird hackish trickery. Plus it was the best architecture I could find in combination with the tech-stack of Electron and VueJS to make it easy to build a run-time skinnable application interface. Which I also wanted to build into my top-level architecture. Not to mention I already had started on a base architecture, so it just made sense to continue to advance the systems integration to support the requirements objectives I set out for myself. 😀
@@SethEden oh OK. Good luck!
@@gachastorys5129 Thanks. Its not a matter of luck any more. Just a matter of time. I've already built out every major subsystem except the GUI. I have a full command engine and custom scripting language and as of yesterday a plugin interface. :-D I suppose I still need a message bus, an event bus and a bindings manager.
Man, this is epic! I always want to know the reasons why people make the decisions they do. Helps for our game dev journeys!
I've programmed some small projects with my Arduino. Currently in our class we are trying to do more complex stuff with c++.
And to see someone building a game engine with c++ is great!
This makes you feel that your programming carrer is a joke 😂 amazing work man! keep it going, i want to see this project grow
Absolutely love your lectures. I would love to see one for your Minecraft in 48 hours video 💙
That would be awesome!!!
I actually really wanted a video like this, thank you
bruh I can't even make a simple game in unity
Just keep pushing through
you couldn't walk when you were born either. the solution is to keep working at it.
Have you tried godot or hazel?
frfr
@@rmt3589 youre right theyre better and open source and hazel is created by @TheCherno or smth so thats cool
Hippity hoppity your code is now my property
But in all seriousness, you are just incredible. The fact alone that you can code in c and even do highly complicated tasks in OpenGL… Cudos.
a one hour jdh video… am i in heaven?
Nice and um this um just what i need "um"
um thanks
Hello big nerd, big nerd and a fan of your channel here. You're really the only gamedev channel I follow right now, really top tier content. You plan on making multiplayer features for this? If not full multiplayer, consider a dark souls / elden ring type multiplayer? Would at least be fun to code networking stuff.
Networking is hard
I really enjoyed this video, I agree that more of these would be really cool to see. Have you ever considered teaching CPP/game dev this way at all?
the code looks beautiful!
I really appreciate you doing such a video, there's a lot to learn :D I also think your amount of use of `std::unordered_map` is very comical xD
I must say you are riding at the apex in the new wave of engineering right now. I wish i were even half as talented
What plugins are you using in neovim? Greate video!
if you’re converting from lab to rgb often, you might want to consider using oklab instead of cielab (i say “sea lab” no clue if that’s correct). it’s better for hue and chrome representation and comparable for luminance, but it’s much simpler and faster. the reference implementation is in c++ so it should be easy to bring it in. also the author has made color spaces comparable to hsl and hsv using oklab which could be useful for stuff like colored lights the user can set the color of, or flowers that can be bred to have different petal colors, or whatever, with a space that both looks right and is easy to use (like having saturation instead of chroma so out of gamut colors are less of an issue). he also has an article on gamut compression so you can transform colors and reduce the inaccuracy when converting it back to rgb
Dude you're an absolute gem. Love watching your game dev journey! Godspeed!. Dude you're an absolute gem. Love watching your game dev journey! Godspeed!.
Holy shit en fantastisk video. Din tekniske viden er vildt imponerende, er det primært selvlært, eller noget du har lært på UNI etc?
This looks pretty good and I appreciate the C++ written as though it was C style. The organization is quite nice. I like your color scheme and I'm wondering if you're using tmux or if neovim has all that built-in? Also, what *was* that at 49:27 ?
ooh that should have been cut out hahaha recording while sick is a dangerous game!
@@jdh But what was it?
you have a really nice setup with your terminal and macos!
Really like these types of videos
If you ever make a course, making an engine like the one you have from start to end product with some kind of playable game, I would pay for it. I'm sure many others would as well.
Indeed, And he can upload his series to Udemy or a similar platform and make some money out of it, I guess there will be a lot of demand.
@@astroid-ws4py Udemy is exactly what I had in mind. I'd love to have an engine that was built from the ground up, and to have an understanding of everything. I'd prefer that over trying to learn how to use an engine like unity.
@@Jova Just like me, I much prefer the traditional software engineering approach for making games I.e. , using open source libraries and other stuff (Krita, Blender etc.) and assembling it all together myself the way I want it.
Imma pay for that too. I seriously would love to explore engine architecture and implementation without getting into openGL.
check handmade hero. it's free
Thank you very much for this!
Exactly what I needed
Subbed, this is amazing content. Random noob question about the BumpAllocator, is it bumping up or down?
Dude this is amazing!!!! Thanks for sharing!!!
I love these types of videos!
This right here most avoid, thinking people wont watch or learn, I'm glad your not the tow the line person, and work against the grain of let some other program do it, or advise people to visit messy forums that tell little about your custom approach. You have my appreciation and gratitude for your work and expertise, but even more for your in depth look into your code logic, and explaining the coding, and your thinking on the route you took. This puts you lightyears ahead of a lot of tutorials, that often only partially explain or like I said before point you to some forum that explains little to nothing and seemingly an ongoing research project instead of study which comes to the conclusion of knowledge and properly used experience, which is the same result in advising a program to run their code and explains little to nothing about their line of thought or the code. Thank you for not being lame, and pretending to explain things which only beg more questions. Not that you should take time to explain all terminology in use of the video, but would be nice to have in description for the key terms used. SO people maybe not as researched a me can also know the reference and meaning of the words you're using in your presentation. A minor nit pic on my part not crucial to those who are going to do their homework anyway. I like your style of layout/structure, it is more organized, and optimization is usually a better idea once bugs are worked out and game functions properly in accordance to desired functionality and desired result. Then makes sense to go back and clean up code, and optimize. pre optimization can and does ruin the progress of many games. Only certain practices in front end optimization aren't detrimental to overall development and usually applies to API's not so much what your doing here from scratch. The main benefit you have is customization, the only disadvantage I see, is portability. Your code maybe less robust than the API driven engines, but is far more manageable to the individual coder, than having assist programs and three libraries open looking for the mistake written in API driven engines, which actually slows the computer and overall progress. Which most API's lack comprehensive interpretation of code, unless towing the line, and remaking what's been made already, and is frowned upon among gamers.
LETS GOO ANOTHER VIDEO :D I've always wanted to make a game engine...
(also i found that programmers often use // in their video titles instead of like | or something.)
Damn, this c++ code look so clean. Most of the time is so hard to read c++ code and with this one is very easy to follow.
Do you plan to release any of your bgfx or other libraries abstractions on github?
bgfx isn’t mine :) it’s a really well done library though, you can check it out on GitHub!
@@jdh lol, looks like I missed a word, I meant the bgfx abstractions you are doing :)
You don't need to apologize for using macros, there's nothing wrong with them when not misused. They're an incredibly powerful tool.
Unfortunately I’m not going to watch through this at the moment as it’s too advanced for me, but this will be great to come back to.
will you make a QnA video sometime in the the near future because I have two questions from you, do you have a degree, if yes, in which subject and to what extend, for example undergraduate or graduate. Second question is how long are you coding from because I recently started coding and your and Sebastian lague video make me question my choice...
Really like your font, what font are you using?
Currently writing a console game engine with graphics and all that good stuff. no renderer, just raw c++ (although I’m still using some windows functions). It’s hell AAAAAA
whenever I think of myself as a good coder, I come back to you to level my ego
will the source code be released on github at some point?
The Cherno has to make a code review on this. I think he'll like it.
2 videos out quickly :o
Woop, can't wait to finish watching this :)
Thanks for the video. A little improvement suggestion to the format: add those youtube video chapters, it would be much easier to jump to section someone might be interested in. Other than that very nice video.
Ticks are pretty common in custom engines, most famous implementation that people who don't code would be aware of is Minecraft, which uses it to handle built in updates and better manage server performance at scale.
This was great and the code review caught bugs, win-win.
Thanks for interesting video! What are you using as an IDE for the game engine development?
I was wondering this too.
hi I wanted to know what you studied before studying game creation it seems very complex for me to start from scratch and make games from scratch without an engine if you have any tips or tell me what I need to study to reach your level
Do you mind telling what is the name of your neovim colorscheme? It looks gorgeous!
thank you good sir for this masterpiece
thanks this video was very informational. also what nvim plugins do you use?
the primary drivers are the builtin LSP (using clangd), nvim-cmp, and FZF
oh this is beautiful, thank you so much!
For someone that is very novice at game dev and graphics programming - where would you suggest going to get the foundational information for game engine development and graphics programming?
So, I'm still starting to explore this myself, but my two cents:
I haven't worked through the whole thing yet, but Jason Gregory's Game Engine Architecture (2019, from CRC Press) is very in-depth. It is over a thousand pages long, but the first few chapters can stand on their own as a very solid introduction, I think. It covers from the basics of how computers work to implementation, discussing a lot of architectural decisions for game engines.
Fabian Sanglard has a series of Books called "Game Engine Black Book": each book is a breakdown of an older engine, like Doom and Wolfenstein. I have only skimmed them, but they might be interesting if you'd rather take a more practical/exploration-oriented approach, specially since you can get the source code and mess with it.
You should be able to find these books somehow if needed : p
Other topics you may want to explore are linear algebra, your programming language of choice, computer graphics/rendering and some methods for dealing with things such as collisions and space partitioning, I think.
as a starter i would recommend you glfw + opengl and GLAD function loader. All of them have documentation. I was learning by seaching an answer to my current problems in those docs and with pain ive done it. For game engine specifically i would suggest you 2 books "Foundations of Game Engine Development, Volume 1: Mathematics" by Eric Lengyel and Volume 2: Rendering. It was practically enough
now that grig mentioned it, if you want to get something up and running quick and prefer videos, "the cherno" has a couple videos on using imGui for that, as well as a series on opengl which I think also uses glfw and glad
Thank you both, this is very insightful.
for both, just read a lot of code. I've recently been reading through OpenMW (github.com/OpenMW/openmw ) but the DOOM II or Quake 3 sources are also good places to start. As for graphics, I can highly recommend learnopengl.com which is very OpenGL-specific but with general principals of graphics and Jonathan Blow's excellent "lecture" on 3D graphics here: ua-cam.com/video/bGe-d09Nc_M/v-deo.html
this guy even wrote his own compiler, what a chad
Why did you made the switch from Visual Studio Code to NeoVim ?
first thing fisrt, love this format, its so intresting to see the little things that you wouldnt add to the properly edited videos,
second thing, why do you use a allocator in the first place (bump allocator), if something is required every frame, wouldnt it be better to just stack allocate it, is there any benefit to using a bump allocator ?
You can allocate deep in the call stack and data will persist regardless, you are not bound to the stack lifetime.
You won't overflow the stack.
you're too good to me jdh
I'd say globals aren't too bad depending on how and why they are used. Making them singleton where possible helps too.
Is your vimrc on github gist updated? Since I think you have changed some things, and I would like to have the nice updated config
doesn't neovim generally use .lua files for the config or am I confused
@@-aexc- As far as I know they started out with .vim files and only introduced .lua config files later. As of now .lua is recommended I think, but most of the configs are still in vimscript since there is just no point in translating it usually
the legend has uploaded
incredible work
Have you considered std::type_index as a key for registering types from different translation units at runtime?
std::map foo;
template
T const & get(ID_t id) {
return dynamic_cast(foo.at(typeid(T))).at(id);
}
I'd recommend std::map as opposed to std::unordered_map because the standard doesn't guarantee that std::type_index::hash is unique between different types (although it suggests it to be).
I did, but the dynamic_cast requirements and continuous hashing of std::type_index make it a performance no-go. much rather just use integer indices into a tightly packed array over a map :)
@@jdh understandable. Don't read the following as me insisting on it or whatever, it's your implementation and I presumed you've profiled it.
std::type_info and the type_index wrapper ought to be linealy ordered types though, so you could have forgone hashing.
One could also forgo the tree entirely and store pairs of std::type_index and whatever pointer-to-base type in a linearly ordered vector if runtime addition is rare enough, and access it O(log n).
If you don't care about deleting those containers, you could be a truly based C programmer and just store ans reinterpret cast a void* so you don't pay for the RTTI checking involved in dynamic casting afaik (as ostensibly you've already paid it by finding that pointer in the vector). You could then store deleters in a separate array that only get invoked when the parent object dies (or not even that, because at that point the application ought to be closing).
Obviously, it will lose to constant time indexing into an array, but the number of components is finite at runtime, and log(n) will probably be rather small, like less than 10.
What I did is make a constexpr template that extracts the signature of the type as a char array and hashes that at compile time. It's compiler dependent though, because of macros like __FUNCSIG__ and __FUNCTION__ . Nothing a handful of #ifdef's won't fix though. But if you've already got a working solution there's no point changing it now.
Curious, would you be willing to share your doom map, editor code?
great video very informative, do you have ur nvim configuration file uploaded some where by any chance?
It's literally linked in the video description (vimrc)
oh..weird I checked thanks!
What theme do you use for you text editor?
He’s too good at this stuff
It's unique in textures but not in general, when coding for 6502, specifically NES, they used Sprite Atlases. Not a new concept but definitely a new usage for the concept and simply genius. They did so to save on Rom and Ram space, and would imagine you saved quite a bit by implementing textures in this method, would be interesting to test and see how optimizing this is.
Very cool, haven't seen the whole video yet obviously, but are there any weird things about the language that you ran into and had to figure out?
the whole thing, I'm a little tired of C++ at this point. very powerful but I miss C!
I would say the weirdest/worst things are constructor boilerplate, template garbage (and compiler errors!) and not being able to make an std::optional.
edit: also the "mutable" keyword is pretty wack
tomlplusplus implies you've familiarity rust, as that sort of popularised toml as a format, is there a reason you went with C++ over Rust as the systems language for this? It's about 50:50 on the gamedevs I watch that are using their own engines if it's C++ or Rust and I'm always curious what drives the decision for them
I've tried rust a few times on smaller projects and have always found that the friction that it introduces with the borrow checker/other extras hasn't been worth it for me. will likely give it another try at some point though!
AfaIk games in Rust always require unsafe code, which defeats the point. That is one reason I never tried, for example, I, personally, tried vulkan in Rust, even though it is possible and people do it it feels for me kinda using the wrong tool.
@@yearswriter Curious about your point that games require "unsafe" code? Is there something specific in optimization or something that pure safe Rust can't do?
@@MrNathanShow No, I mean practically, every library that uses vulkan needs to disable borrow checker at one point or another .
I am sure it can be abstracted, but I am not game dev, but I do hobby stuff every now and then, so maybe there is some obscure way to do that.
It is just practically, it was really easy to finish any vulkan or OpenGl tutorials out there to the point of having some scene.
@@yearswriter The whole standard lib is full of unsafe code internally, still everyone uses it. I think if unsafe code is locked away in some safe abstraction over it, that's fine. In the end that's how whole Rust works.
how do you go about debugging your code in neovim?
i just use LLDB and occasionally hop into CLion if it’s really bad
Are you using a plugin when you search through your file system for a line in the code? Or is it built in nvim? Thanks!
That's the fzf plugin for Neovim
3:00 for me global state is only worth in game dev. In any other kind of application, global variables are a bad idea, but for a enclosed world it's very handy have things like player's state accessable globally
In other kind of apps your application logic is not limited to 16ms execution time. First thing I noticed when I started game development: performance matters.
In Web Development, frontend frameworks like Vue, React, Angular utilizes the idea of a global state, so individual components can interact with the global data or send these information between each other
Hey, can somebody tell me which plugin jdh uses for the quick open feature? Loved the video btw, hope you'll release the code at some point :)
FZF!
Do you have a course or maybe a playlist where you teach things ???
Can we connect to you on any social media handle ?
a small Question, how long have you been programming for?
So I notice that only when you talk can we here background noise or any noise in general. Is that noise canceling or something? Or are you just editing out all noise when your not talking
One important reason why global state is discouraged: When you depend on that "global" state, especially on a top-down approach, you create a dependency on basically everything. This can make it harder to visualize what depends on what, to refactor and also result in long compile times. If you make sure to only give your classes access to what they need, eventually through small interfaces, it's easier to manage dependencies.