Programming a multiplayer game from scratch in 7 DAYS

[@tr7zw]

Take a shot every time jdh starts a game from scratch

[@jdh]

quick way to get alcohol poisoning

[@siteking4289]

@@jdh Hard mode: When he implements shit on his own and trying to reinvent the wheel rather then using a robust library

[@Finkelfunk]

@@siteking4289 So basically continue drinking constantly?

[@sir_chaotic]

You're dead. No big surprise.

[@domeen0gt895]

@@siteking4289 Tbh I can kinda respect his determination.

[@onlysmiles4949]

Honestly, the idea of enemies being able to light their loot drops on fire before they die is really funny ngl

[@timecubed]

I feel like there could be reasoning behind loot drops being set on fire/carrying whatever status effects the enemy had before dying. Like the spell affects the enemy *and* whatever it's carrying too

[@HexaflexagonFan]

It could be a decent balancing technique

[@TheVestinius]

its a feature. not a bug :)

[@ViktorSarge]

Dude. You make it look reasonable and almost easy implementing things from scratch in C. That's a feat in and of itself.

[@Nick-yq5uz]

After he added serialization to C++ I’m convinced he can do anything.

[@0x5DA]

not to undermine his talent but modern C isn't so crazy.

[@clintonhawkins8666]

I think the flaming coin bug should definitely stay!

[@cometeova]

Exactly - my first thought when I saw that part was "Is this a bug, or a feature?"

[@HisVirusness]

Don't feel bad about starting a project, getting so far that it's almost complete, and then getting sidetracked and starting something new. It happens to the best of us.

[@cluelessadc]

this guy is the best of us

[@wildmaknae_]

im an artist and feel so called out rn x)

[@robinHobin]

It says in the vid for a split second he is still working on the cos but has nothing interesting to show rn

[@keshi5541]

Artists be the exact same 😂😂

[@Dollar_CoinYT]

I feel like he is trying out multiplayer to try to add it to the other game

[@btarg1]

Writing network code without libraries looks incredibly complex. Love every devlog! I really admire the dedication to the bit with using no libraries even when it's an active hinderance lol

[@jdh]

active hinderance or learning experience? you decide!

[@robinHobin]

Both@@jdh

[@SolarShado]

@flaviog141 Eh, I duno if invoking POSIX syscalls directly really counts as "a library"... I suppose it technically counts, as it is part of the C standard library, and it's not like directly bit-banging raw network packets at the NIC over the PCI bus, but still... And building something useful on top of raw buffers may not the terribly difficult (especially with some experience under your belt), but it's not exactly trivial either, especially in just a day or two.

[@atiedebee1020]

​@@SolarShadoit's not part of the C standard library

[@SolarShado]

@@atiedebee1020 Ah, fair nitpick! Technically the networking API used here is part of POSIX, not part of _the_ standard C library. I probably conflated them because I mostly know about them via Linux, where both APIs are typically provided by glibc.

[@divine203]

I absolutely love your approach to game dev. Whenever i feel burned out from working on a project. I just watch your videos for motivation. Splendid work as always ❤

[@danielgysi5729]

The things you did in a week would've taken me at least a couple months. Your talent and work ethic are amazing

[@spaghettiking653]

9:31 Wtf, don't just say you casually made the entire UI look that good in half an afternoon! This is incredible, I can barely make so much as a menu that works, let alone something this pretty.

[@buildgameswithjon7641]

I literally said "no you didn't" seconds after that time stamp lol

[@spaghettiking653]

@@buildgameswithjon7641Samee

[@lukasnick5511]

it is so impressive how you manage to pull off programming a working multiplayer game in such a short time!! I really admire your work!!:)

[@spluf1081]

i never comment on videos but holy moly man ! you covered a good chunk of topics from 2 courses which i had this semester in a 1 week, gracefully, from scratch and made it look easy !! i know how much i struggled when understanding packets (we wrote a program for processing, NAT translation and portforwarding) but seeing you do it from 0, make everything multithreaded and not drop packets from host to player is insane, well done :)

[@petlahk4119]

As a person thinking about what I want to learn next, what were those two courses?

[@hedwig7s]

1 week? Good lord that's very impressive good job man

[@justinj0824]

Watching Dani make games then watching JDH make games is actually the funniest juxtaposition ever

[@lilium724]

The concept of sending the player position directly to the server is also how Minecraft handles multiplayer. The way they (try to) prevent hacking is by only checking a few edge cases on the server side to prevent obvious cheats, like if the distance between the old and new position is too big, you get sent back, or if your vertical speed is 0 for too long even though you're not standing on a block, you get kicked out.

[@vitao95]

The monster loot catching on fire is some real dwarf fortress material. Great video and project as always!

[@Baaqel]

The speed of light is unknown in 1 direction, at 7:00 the diagram shows that it takes 100ms to travel to the server and 100ms back to client. Theoretically it is equally as possible that it could take 199ms to send to the server and 1ms to send it back, or any numbers that add to 200ms. Just think it’s kinda interesting and wanted to share

[@ezrakornfeld8436]

Ok yes but that’s a theory. Occam’s razer.

[@Baaqel]

@@ezrakornfeld8436 Yes, it’s only a theory, but even Einstein says that the speed of light and clock synchronization is only defined by convention, rather than a measurement. I agree that the most simple explanation to our understanding would be for the speed to be the same, but it’s interesting to me that this principal that is base to our understanding of the universe isn’t fully understood.

[@jdh]

for sure! my example was definitely a bit contrived

[@eDoc2020]

The speed of light doesn't really matter, just the speed of packet transmission. Over the Internet it's very likely that the packets each way are taking different paths.

[@Baaqel]

@@eDoc2020 The time it takes for a packet to reach a server from a client is unknowable. No matter the path it takes or the distance it travels, it can only be assumed or measured when the server sends a packet back to the client. It’s not really important to this video though

[@iamjessieray]

I honestly don't know why, but I love watching every video you do. It scratches some part of my brain that wants to do stuff like this but that I don't have time to do because of working and having too many other things I want to do. It does give me some inspiration to actually work on the programming projects that I am actually working on though.

[@idjles]

You need synergy spells where one wizard does a fire spell and the second wizard does an aspect - these then combine to attack an opponent. You could have scissor-paper-stone on fire-air-water and pulse-quick-slow aspect. This requires you to know the enemy and coordinate on spells. Or one casts a region spell that the other casts into. You could have probe spells that test the features of the enemy. When two enemies are close they enhance or disable each other. You could have bosses that shift aspects over time or in response to particular spells. Powerups to shift aspect/element. You could also have a-b-c combo spells where you cast a, partner casts b and the you cast c - knowing that a-b-c does extra damage/freeze to enemy.

[@JordanDeMexican]

This comment needs more likes 👍

[@Gavinwasalmostcool]

I was just checking your channel yesterday to see if you'd uploaded. I'm very excited to watch this one

[@eboatwright_]

This is awesome! I've been watching since the Minicraft remake, and your stuff just gets better and better! Your FPS game is looking amazing, and I actually really love the main menu for this one lol

[@goddtriffin]

Building from scratch like this honestly feels more sane than using libraries. It really doesn’t have to get any more complex than using send() and recv().

[@nulifyer4460]

One of the few places I can come to see games written at this low level, thank you for your content and hard work!!!

[@RossWasTaken]

When jdh doesn't upload for 7 months, you know a banger in the works

[@Bozebo]

Good job. I had to write a paper on this "Fast Action Multiplayer in P2P Networking Over Mobile Connections" or something. A bit of reliability over udp (tip: bitfield of acks n packet count and back), sub message resending with classifications (lossy, priority, etc.), host change resyncing, hole punching, matchmaking, relay fallbacks, some spline extrapolation (first network tracking entity movement as paths over keyframes synced by time then again in opengl renderer thread), exponentially smoothed average on the latency, fun times xD

[@jdh]

sounds interesting! Though I didn't mention it, I used TCP for this in the interest of not wanting to handle all of those things but if this networking backend gets used elsewhere (maybe in a fast paced retro FPS who knows) then I'll definitely want to make the switch over to UDP and handling the reliability issue myself. Do you have any good links to papers/resources/etc.?

[@skeezixcodejedi]

*drums fingers* *waits around meme* Hope you've progressed some of your projects and are slowly get rich, but we await your wonderful brand of video :)

[@bkucenski]

Using a buffer for data going in an out and then parsing messages in bulk makes TCP/IP super happy. It's a streaming protocol, not a messaging protocol. Your header can be used to see if you have a complete message or need to just let the program do other things and check again when it's done processing game logic. If 100 messages come in between frames and you process them all at once, your game appears to be much smoother. And you can break actions up between multiple messages simplifying your game code.

[@jdh]

yep that's what's going on for this game! I didn't have time to show the ~2-3k lines of packet handling/serialization/netcode here but basically the packet buffers (a big loop that send()s outgoing packets and recv()s incoming packets asynchonously, (de)serializes them, and dumps them into a buffer) run on a separate thread and then the client/server process/apply them when they have time to keep the simulation running smoothly on both sides

[@jdh]

when either client/server enqueue a packet, the packets are pushed onto a thread-local buffer which is flushed (copied over to the packet handling thread) at the end of each frame (for the client) or the end of each tick (for the server) so it doesn't get in the way of anything else

[@alfredenglund]

Im on my last term of my second year at a master's programme in computer and information engineering and this video was an absolute blast. I was surprised with how much I understood of all the really techy/nerdy stuff, and it was just really cool to see how everything was implemented. I would love to see more of the engine programming and implementation though.

[@Stoolan-nd3gn]

I am going into 9th grade next year and am doing AP computer science and up until I started watching this guys videos I thought I knew a thing or two about programming. After watching these videos I am in utterly disbelief that one can even do any of these tasks the things he does are absolutely insane.

[@madman6361]

ap comp sci freshman year? good luck man!

[@Wyklepheph]

I helped with a macro to enable authoritative servers for an RPC library written in Nim. All the actual netcode works on a custom implementation of UDP that keeps the packets in order and resends dropped packets. It works pretty damn well. It’s actually insane; the macro creates all the boilerplate on the client and server so that a client can call server functions and the server can call client functions. The dude who wrote the base library is a very smart dude, I learned a ton

[@Wow-wk7eu]

You are a great inspiration to me as someone learning to code. Great vid and congrats on that sponsorship

[@Thzyr]

wake up hun, hes back.

[@aserta]

He's about to cook for the whole family!

[@domeen0gt895]

I'll get the broom...

[@d_00]

Your videos are so well done, I've watched some of them more than multiple times, and now your editing has improved too! Really great content, you inspired me in many different ways and I hope you'll continue to do so for everyone that gets the chance to know you.

[@doggo_idk]

great video as always, to show input lag, assuming you are using OBS (and not a screen recorder you made from scratch), you can use the same plugin that streamers use to show their keypresses. either visualy or by text.

[@M_BRINE_85]

Please continue this game it has so much potential

[@C_J_Patto666]

love the video! as the first vid of your channel ive seen it really hooked me in and i cant wait for whatever comes next. do you have any rough estimate of an itch publish?? i really want to play this

[@magnusfrlund1605]

You its a good day when jdh uploads

[@aziwii4052]

I'm in awe after discovering this channel. I'm taking cs in university right now, and I'm just curious how and where you learned all of this stuff. It absolutely baffles me. I would love to see a video of your journey through coding, math, development, etc. Or I guess you could just reply to my comment lol

[@neverix_3600]

This is insane, you'r an inspiration to me and i can only hope to come close to this level of expertise!

[@stevemcwin]

Finally jdh finishing a game. Entertaining video as always, hope you make more soon!

[@FallKK]

Seeing stuff like this inspires me to be a better developer. I love C but only ever just do web backend for work. I'd love to get more into things like this

[@Diamonddrake]

As a fellow software engineer it’s impressive what you’re able to achieve in such a short time. We all say we can do things in a week, seldom does anyone produce something that looks this good in twice the time.

[@btarg1]

FINALLY! been waiting for another video forever!

[@R1fleman]

your crazy good some people cant even make a multiplayer game with a game engine and you made it without a game engine

[@Ketpain]

As someone getting started with programming and taking a long time to grasp things. I feel like jdh be flexing on me .. 😢 Good video! 👍

[@mdnghtppl0000]

I was just hopin for a vid from u soon, great timing

[@keaganrice8656]

Status effects applying to everything sounds like a fun idea. I'm a firm believer in multiplayer games giving you the ability to screw over your teammates (and yourself). Works really well in Lethal Company.

[@gbpferrao]

dude it looks so beautful its pleasing to just look at it

[@vaxaop7838]

The game actually looks fun, and this video was really instructional. Thanks a lot jdh for your amazing content!👍

[@ValDominator]

the scope creep is incredible

[@krammehl]

Cudos to you for writing your own netcode! I bit the bullet and wrote my own networking engine after years of dealing with a buggy library. Can recommend.

[@icantstopsuffer]

13:50 this bug 🔥🔥 really would like to see it as real mechanic in some game

[@oldgangster4119]

Thats what i thought, its a feature 😂

[@BananaMan6763]

This is one of the channels I have subscribed to because what they do seems very impressive and awesome to me, even though(especially for this channel) I don’t understand most, if not, anything talked about.

[@davidbasilefilho]

please continue the last video's project!! it looks so damn good and fun

[@danius_huganius]

jdh, this is the fifth time you present a game made from scratch in this class

[@marsimplodation]

I can 100% relate the pain in the networking part of the video, I atleast had unity to deal with the complex stuff, but I feel you

[@OneLabToRuleThemAll]

The recipe joke at the beginning is just beautiful

[@artvandelayimports]

Starting a new project is common but at least you’re achieving some of the core goals for each project you make, that’s all that really matters. I remember following this other KZbinr who’s been working on a game since 2016. They just keep reworking and rewriting their game base instead of making progress on the game as a whole. For a while, they got so distracted from making their game that they started creating a new programming font and customizing an open source editor, blaming their existing tools for their slow progress. Stopped following them a few years ago but I’d bet they’re just rewriting their game base again

[@4F6D]

Talking about Randy huh?

[@GuildOfCalamity]

Super cool, getting a real Gauntlet vibe from this.

[@xanrerkazuki9929]

Unique enemies with random stats would be a cool addition and a challange.

[@Lolboy30]

i just like to program little games as a hobby, i am 100% self taught and after struggling to understand how to serialize non-basic types for a while now this motivated me to search for answers again - if you or anyone in the community have any input on that it'd be highly appreciated, and thanks for the motivational boost!

[@no-one3795]

This could be a great multiplayer roguelike game.

[@soupnoodles]

Remember guys this is the same person who said the internet was an unnecessary dependency Awesome work as always, your videos are always so mesmerizing to watch. You shoulda released at least a dummy version before you quit this project too, we could have at least tried it :(

[@abyssaltheking]

love your stuff, man, even if i have no clue what you're doing, lol you mentioned the fps game, and it looked cool in the last devlog, so im curious on how it's going

[@ShotgunLlama]

That macro sorcery was by far the most interesting thing I've seen in the past 60 minutes

[@Catherine-m2p]

YAY i just got re-obsessed with you thats such good timing

[@abrarmasumabir3809]

please make a video about your setup! Your vim looks really awesome for c++

[@robinou21]

Congratulations, and thanks for the video, it’s amazing

[@crefelder1]

This is impresive. I am working a lot currently in SDL, but need more time for it. For network stuff i would try it with a common lib.

[@BasedG23]

Dude how on earth did you learn to code this well. My brain can’t even fathom.

[@venilc]

you scare me with what you're doing. you make me feel dumb with what you're doing. and i love it.

[@Arcade_Archie]

Any sufficiently advanced bug is indistinguishable from a feature. ~Rich Kulawiec

[@zoeythebee1779]

Omg mental health problems can wait JDH POSTED!!!

[@divine203]

😂. He's dat important?

[@truestprophecy]

you are basically the best programmer that I am aware of.

[@Storm_VLRT]

The pixel art is actually so pretty

[@tumbleweb]

15:50 Would have been funnier to give yourself an 8/10 since its IGN

[@EranStockdale]

Nice work! This looks really fun :P

[@xoanaraujo]

Your skills are amazing, loved it

[@oglothenerd]

Honestly, you should try Rust. The macros there are pretty awesome! :D There are people who have made Rust macros that are themselves programming languages, and even through compiler errors just like anything else! Rust also has a really solid type system. Another awesome language for the C purists is Zig. Zig also uses more Zig code to write Zig code instead of a macro system. Rust is also memory safe and thread safe without anything gross like a garbage collector. It uses compiler rules to make sure no memory leaks happen. The thread safety also uses the trait system to implement a Sync and Send trait on some datatypes.

[@catriverr]

Program this. If you upload within the next 2 months I'll become a patreon member.

[@JaniEU]

Nice video as always, I have no idea how C works and no idea what anything you say means but your videos are still entertaining

[@sillygaby_]

man you have inspired me to do so much stuff, this channel is like a gem in a pile of shit that is modern youtube

[@philosophiabme]

hey man, you're pretty good at this stuff

[@randomgoose2606]

for so little days of work that looks really sick

[@INsanityDesign]

A new vid by the GOAT ^^ I will just bury myself in awe, picking up my jaw after it dropped . . . I am too stupid for the world... But you sir, please continue to be awesome :)

[@Retrosen]

bro is a complete menace in programming

[@rafaaaaaze]

Looks really cool, great job!

[@SlothFang]

Coin bug should be turned into a feature. Allow the zombies to take damage from the fire coins!

[@HarhaMedia]

That's an incredibly productive week!

[@bloodsmithgamer5071]

Dude... You've inspired me to start what is probably a completely inane project, given how little experience I have with C. Daggerfall clone (on a small scale) using SDL 1.2 and OpenGL 1.5 😅

[@animeturd2280]

He’s baaaack it’s almost been a year or 2 or 1000

[@PseudoCode1090]

Itch, link ! Itch, link !

[@CaptainDouchie]

i am really inspired by you sir, could you make a video on how u even go about learning all these sort of stuffs in order to build all the projects u had been doing from scratch?

[@Voidkitty_]

No one: JHD: I'm bored time to create a game from scratch in c in an arbitrary deadline that is way too short

[@dailydoseofshtposts6891]

I absolutely love you sp much❤❤ cant belive you gave us a will to live again🎉

[@PaGow]

That game looks hella fun!

[@ThePoinball]

Dude I want to play That Game!

[@clonkex]

This is incredible impressive! And you've discovered why pvp networking is so ridiculously difficult. It's physically impossible to create perfect netcode but players think it should be perfect so you will be crucified no matter which tradeoffs you make. Of course, sometimes your netcode is legitimately buggy and you deserve criticism lol

[@luke.wayneee]

When I see "seriously go read these articles they're great" Im dead inside already reading it

[@raz0rblade06]

man i failed my physics exam today, your videos always make me feel better, thank you

[@dennisrobinson4739]

You just explained my networking project thank you ! Haha