multiplayer

[dire thorn]

I was looking at Mover as well but the lack of documentation and generally any information at all is a big turn off

[lost inlet]

Mover has a bit more activity than I was expecting to see

[lost inlet]

Welcome to Unreal Engine

[dire thorn]

Oh I'm aware, been using it for a long time but never dug into multiplayer until now. I feel like 5.4 was a big step up in some areas of the docs though

[lost inlet]

https://github.com/EpicGames/UnrealEngine/commit/52be71dfce4d51b6d5782960c6d67ff50834ab81 at least Mover means NPP also gets attention

though this is the only significant change in a while

[dire thorn]

Hm well, I guess I'll just go with the good old CMC for the time being until Mover has matured a bit at least

[latent heart]

I poked the guy myself and he seemed very open to actually getting it sorted.

[halcyon ore]

My usual fix BP side, is just trigger the rep notify/ edit on begin play.

[nocturne quail]

if the vps server is not stable, it could be the reason of clients crashing?

[thin stratus]

I literally just did that to our local version haha

FML for spending time on it I guess

[thin stratus]

I think that's triggered by SirKai PR having that stuff in it

[thin stratus]

Actually, that is just a very small change. I actually turned the whole Mover plugin up side down and got rid of all FNames for Modes and Blackboard.
And also (in a previous step already) added full Tag support to the Blackboard.

[vital furnace]

i want to return a value, but i can't because i work with custom event. how can i return that value ?

[thin stratus]

Using a function instead

Events can't

[vital furnace]

i want to call a replicate function in my widget who can return me a value. how can i do that ?

[thin stratus]

You can't

Replicated Events, aka RPCs can't return values. You would need to send a second RPC

[lost inlet]

Now if there's a built-in solution for having clientside interpolation for the fixed tick policy now that'd be something

[thin stratus]

Also keep in mind that widgets can't have RPCs in them. The RPC itself needs to be somewhere else @vital furnace

[latent heart]

Heh

[lost inlet]

It was good enough for Quake

[vital furnace]

yes i know, that is why i call a replicate event in player controller and iwant it to return me a value. how can i do that ?

[thin stratus]

Send a second RPC into the other direction

[vital furnace]

please make me visualize

[thin stratus]

??

If you have a Server RPC in your Controller then use a Client RPC to send data back

There is no return values for RPCs

[vital furnace]

thanks

[crisp shard]

When packaging a game w multiple levels in the project , should I be deleting levels im not using or does it not matter if they are not being used in the logic / game (currently)?

[quiet fjord]

Does anyone know why serverTravel does not create the playerControllers when we use it with a dedicated server as gamelift

If I play it as as client it works

[thin stratus]

When packaging you can usually select what levels to package.

[thin stratus]

wdym when you play as a client it works?

And wdym with "does not create the playercontrollers"?

[crisp shard]

amazing, yea im clearly a noob have not packaged anything yet and im so worried for whats about to go down

[quiet fjord]

@thin stratus The problem I have had for days. I have a dedicated server created with gamelift and when I have a certain number of players on my map server lobby and I do serverTravel in its gameMode it makes the map change but it does not create any player controllers therefore I cannot control the players. This only me It happens when I play it on a dedicated server.

[thin stratus]

Do you say that because you know the Objects don't exist, or do you say that cause BeginPlay of the PlayerController isn't calling?

[azure narwhal]

hi, Im new to multiplayer in unreal. is there a way I can turn off this Niagara effect when you are playing as the character but can still see it when looking at the other player. so turning it off for myself but still have it show in the game.

[dark edge]

make it state driven

[quiet fjord]

@thin stratus What really happens is that the postLogin of my destination map and using seamless travel does not create any player controllers, therefore the gameMode of that new map is not being called because my server crashes. The same code works fine for me in ue4

[dark edge]

what is the effect? Is it meant to always be there or indicate some sort of state?

[quiet fjord]

this running on a dedicated server with gamelift

[thin stratus]

SeamlessTravel doesn't call PostLogin

I'm relatively sure that your PlayerControllers create just fine.

You are probably having code hooked up to stuff that works nicely in HardTravel situations, but won't work on SeamlessTravel.

[quiet fjord]

with the handle node Starting new player doesn't do anything for me either

[thin stratus]

I wouldn't know why PlayerControllers won't create if that's really happening.

That would point to an utterly broken Engine

[quiet fjord]

I have seen the different logs. And on the server it does not do the serverTravel and my clients do, therefore the session is closed for me after a while

The strangest thing is that the same code works perfectly in UE4 4.26

[thin stratus]

I mean, 4.26 is what, 3+ years old?

Lots can have changed

[quiet fjord]

I don't really know how UE5 works with smooth travel.

The problem is that it only fails for me on a dedicated server hosted on gamelift

[hollow bridge]

Is it possible to filter anim graph nodes in dedicated server? I don't need all the blends in the server

[azure narwhal]

Im having an issue with the weapon that i am attaching to the player. The weapon in my hand is the one we see and the one in the air is what they see . it looks like its attaching properly (second picture) but when I unhide the pistol its stuck in its starting position and wont follow the transform. can someone help

[strong vapor]

[Question] What's the best way to handle sprinting if I want to gradually increase and decrease velocity.. and not have it lag.. I've been testing a few different ways out.. and when I use some artificial packet lag it always hitches

When I'm sprinting and I stop sprinting, I want the character to gradually slow back to their normal MaxWalkSpeed... to do the gradual speed up, I used MaxAcceleration

but kinda stumped on how to slow down gradually without it having rubber band effect when there's lag

[mystic estuary]

Customise UCharacterMovementComponent to allow client-side sprinting prediction

[strong vapor]

ok cool, we do already have a custom CMC.. what would you do in there specifically?

[mystic estuary]

Create custom network prediction data for the client and custom saved move; you would need to fill then with the sprinting state, so that the client can predict it. In the custom CMC you would need to package and dispatch those packages accordingly. You can google that as there are plenty of tutorials about that

[normal raven]

So I need to have an AActor that belongs to the server (be it dedicated or listen server) that I can use replicated functions with. It can either be placed in world or spawned at runtime. But I don't necessarily have a PlayerController to give ownership to.

[mystic estuary]

Anything that doesn't belong to a client, automatically belongs to the server. You don't have to own an actor to perform RPCs as long as it's replicated

[strong vapor]

you won't be able to have clients call server functions on it though

[normal raven]

Ah, see there's the issue

[strong vapor]

it will be able to multicast down to everyone.. but your clients have to have ownership of something in order to call a server event

[normal raven]

What's the best method then?

[strong vapor]

might consider just... giving ownership to whatever client needs it at the time

[fossil spoke]

Use the PlayerController instead.

[normal raven]

But what if it's a dedicated server?

[fossil spoke]

If you want to encapsulate and abstract away the details of what you need to have done specifically, put it all in a Component that you add to the PC.

[normal raven]

Ok yeah that was actually my original approach, but it felt funky

[strong vapor]

I worked on a game that had like a shop keeper.. and it would spawn an actor that we'd give ownership to for the client.. and that's how the client would buy stuff.. it would be talking to ITS actor that the shopkeeper spawned

[fossil spoke]

Make a Subsystem that manages the details on the Server side if you need a centralized place.

The Subsystem would talk to the Components on the PCs

To do the network messaging

[normal raven]

Yeah, gotcha

Ok thanks

[normal raven]

Yeah but this is like a central terrain chunk manager. And I need to be able to have lots of players modifying it. I don't think I want to be changing ownership a whole bunch for this

[fossil spoke]

Yeah then have a Component on the PC that is the TerrainModifierComponent

Which talks to the TerrainSubsystem

🤷

[normal raven]

Yeah that makes sense. Shoulda stuck with that approach haha. I was trying to reduce bloat, but I guess I oversimplified things.

[fossil spoke]

How new to game dev and programming are you?

[normal raven]

C++ maybe a year and a half. Haven't done much multiplayer in C++ till now though

Been doing blueprint for like 8 years though

[fossil spoke]

Ok

[normal raven]

But I definitely don't mind getting my hands dirty with C++. It's what I'm using for this plugin. I like it better than BP

[fossil spoke]

Premature optimization (this includes combating "bloat") can be detrimental.

It sucks development time and impedes your ability to iterate properly.

[normal raven]

Yeah, I've heard "Premature optimization is the root of all evil". I guess it's kinda true 😅

[fossil spoke]

First pass on systems design and implementation should be focused on just getting the idea working.

[normal raven]

Wise advice.

[fossil spoke]

When you have it working how you envisioned, you can then take it in as a whole and evaluate it with the rest of your systems.

This helps identify areas that need improvement.

One of which could be performance

Second pass is when you focus on those elements of improvement.

Because you can formulate a plan on how to achieve those goals.

[normal raven]

Yeah. TBH I've really given in to scope creep on this project 😅

Mainly in optimization. Which I do realize is a problem.

[fossil spoke]

Optimization should not be considered a whole lot at the start, at least not that which is beyond the obvious.

[twin juniper]

really? I'm currently doing the complete opposite and trying to get everything perfectly right the first time

[normal raven]

This is definitely the advice I need to hear right now

[fossil spoke]

Well stop it, you will be more productive.

[lost inlet]

I think you should get it good enough at the start

[fossil spoke]

Obviously if its tanking frames, thats an issue.

[normal raven]

Having a good plan is one thing. Constantly reworking it is another

[fossil spoke]

Designing things on "paper" first is also a beneficial practice. It allows you to think through the problem space and identify possible pitfalls in your initial assumptions early.

https://app.diagrams.net/

I use this online tool quite often to sketch systems before writing any real code.

[normal raven]

Interesting!

[fossil spoke]

You can think through a pseudo implementation before actually committing to anything.

[normal raven]

Yeah that looks really helpful

[fossil spoke]

It can take extra time to do this, but it is worth it.

Especially with larger systems. It gives you a reference to point to as well.

[normal raven]

I think this really is the hole in my workflow right now. I've been hitting a lot of roadblocks recently and a lot of time it's been lack of foresight.

[fossil spoke]

"Paper" design helps a lot with foresight.

It helps you predict outcomes.

See around corners.

And enables you to address them before you really encounter them.

[normal raven]

For sure

[fossil spoke]

So my advice is to try and practice that.

Start small.

[normal raven]

Yeah. I'll gladly take that advice. Wish I had started that way 😅

[tired current]

Any suggestions on tutorials that make a multiplayer game in unreal just to get comfortable with it, cpp or bp is fine

[twin juniper]

learn multiplayer

[fossil spoke]

Take a look through Epics Youtube channel, they should have playlists of things like that.

Also generally just search on Youtube for that exact thing.

[tired current]

Cool will do

[fossil spoke]

There isnt going to be a single tutorial series that will perfectly cover all aspects of multiplayer development.

It takes time to learn and from different sources.

[tired current]

Yes I know I just want to get familiar with RPC workflows and such

Part of the journey

[fossil spoke]

Have you read the Network Compendium?

[tired current]

Yes

https://cedric-neukirchen.net/docs/category/multiplayer-network-compendium
https://wizardcell.com/unreal/multiplayer-tips-and-tricks/

[fossil spoke]

Read it again

And then 1 more time after that.

[tired current]

I have lol, i probably will read it even more. Just curious if there were any tutorials people thought were great. I’m gonna search on YouTube to follow whatever good one I can find right away just to get comfortable.

[twin juniper]

Honestly, 1 time is correct, but you have to practice what you learn

that's really important

[devout sonnet]

I tried using CHATGPT to help debug this and tell me what i'm doing wrong but it just keeps saying the same things over and over. Why isn't the first person who entered a number not getting their widget updated?

[sinful tree]

Use OnRep. Don't use Multicast.

Part of your problem could be because of when you're constructing your widgets.
You won't get a valid playerstate until it effectively "Begins Play" so if you happen to construct a widget before then and don't have anything to let you know that another player has joined later, then you'll never have an appropriate way of referencing the player so you can't get its number.

[devout sonnet]

I'll see about changing that.

[devout sonnet]

What do you suggest I do?

[sinful tree]

You can have something that properly constructs the required widget when the PlayerState begins play

[devout sonnet]

Thanks, I'll look over those blueprints. you always are the most helpful.

[ancient adder]

What happens with a replicated property in the following case?

• Update1 sent
• Update2 sent one or two frames after Update1 was sent
• Update1 was lost(Packet loss)

Will the client receive Update2 Only, Update2 then Update1 or Update1 then Update2?

[fossil spoke]

It will receive the most up to date state.

So Update 2

Otherwise, if it was to resend Update 1 after Update 2 was received, that would be a desync.

[ancient adder]

Thanks! 🙌

[woven basin]

Is there any guide what the definition of an ActorChannel actually is? There's nothing in eXi's guide, and WizardCell refers to it twice in his tips+tricks.

Searching here on Discord, I think we are saying it is the connection of a replicated actor from the server to the clients version.

Is it one actor channel per spawned entity, or if I have 2x MyActor is it one actorchannel for both of those?

and it sounds like components of a replicated actor use their parent actor's channel to replicate through?

[fossil spoke]

ActorChannel is a low level concept so its not really something you will interface with directly.

It is a per Actor instance connection.

It is the pipe between the Server and Client version of the Actor instance.

And yes, Components attached to that Actor will use its ActorChannel to replicate.

[woven basin]

yeah - the reason is the phase that Reliable will result in RPCs garunteed to remain in order if it is part of the same ActorChannel.

Obviously we normally never assume the order of RPCs, so I'm just trying to make sure I understand the logic of when I can actually assume the order

thanks though - that does help clarify the meaning

[halcyon ore]

From my quick Convo in #cpp message

How do I guess?
Go about "conditioning" an entire actor?
Much like the net cull distance squared, or general UE, where you know of stuff around you, instead of the entire map.
But, far more controlled.

Also, any way to know when it happens?
I understand the client has begin play, but does the server have some like added controller to relevance, or removed controlled from relevance

Another thing that would be of use to me, rather then maybe doing something complex.

Any way to have actors be always relevant for some clients, and thee rest following a net cull distance squared type setup.

[crisp shard]

does anyone have any advice on creating a turn based system where it's really 2 sides and they take turns ? any good things to keep in mind or follow ?

[hushed sigil]

I don't think that complicates things, if anything it should be simpler than most multiplayer setups

[crisp shard]

tbh was thinking the same thing but i think initial setup is what im looking for some guidance on

looking for a tutorial on liteally a setup of 2 sides, player 1 turn, perform actions, act, players 2 turn, etc

[modest crater]

You might be able to just override and extend IsNetRelevantFor

[fossil spoke]

@halcyon ore You may want to look into the IsNetRelevantFor function

[modest crater]

tbh it just sounds like you will need to extend AGameModeBase and go ahead and put in a "state" like system for turn behaviour, you could probably do it also without a gamestate but that sounds exactly like what you need to do

(this doesn't help you but I am planning on git open releasing a gamemode/state frame work plugin I am working on that allows you to have game states represented as UObjects that can be extended and override things like ExitState, TransitionToState etc. It should be nice because when I started extending UE's gamemode/gamestate I really didn't enjoy it at all)

[chilly haven]

Hi,
For hosting linux dedicated servers for a steam game, is GameLift generally preferred, or vanilla AWS? If so, why?

[fossil spoke]

There is no general preference for those types of things.

[halcyon ore]

How does that interact in general I guess?

Does it calculate on tick.
What if I first want it to not be relevent, then 1 second later, be relevant? does it calculate on tick constantly?
Or, how do I guess add an actor to the like "try to be relevant" pool?

Also, what if I want it to no longer be relevant later?

[modest crater]

You should read into how unreal gathers a list of actors to replicate every frame, it will give some insight but yes, it will be queried whenever it is going to update on the server if its even relevant for

[halcyon ore]

How about data?
Does the client just have the CDO info, or the full actor data?
and, if so won't that not help me?
It still uses network calls, and time?

[fossil spoke]

IsNetRelevantFor is only called on the Server.

Look at the base implementation of that function on AActor

You will notice it handles bAlwaysRelevant etc

[halcyon ore]

Oh, I must've read something wrong.
Thought I read it as running on client side

[modest crater]

https://dev.epicgames.com/documentation/en-us/unreal-engine/detailed-actor-replication-flow-in-unreal-engine

[modest crater]

Here, I know it was an older convo but I just seen this now https://dev.epicgames.com/documentation/en-us/unreal-engine/replicated-object-execution-order-in-unreal-engine

[crisp shard]

thanks yea i was suspecting gamemode would be where this would primrily done.

basically a setup like the game in the image is what i'd be aiming for. 2 sides , 1 side does it's actions/attacks/etc, then the other

[modest crater]

GameState, its the only thing that is replicated that controls game flow, clients wont have game modes

[nova wasp]

now that is a blast from the past, wow

the sniper was op

[crisp shard]

lmaooo, glad someone recognizes it

was a classic

[crisp shard]

ahhh gamestate. will def need to experiement to get things setup, never have made something like this

gamemode would just know who's turn it is for example ?

[modest crater]

enjoy, I more or less just copied AGameMode and AGameState but I started from the Base classes to implement it better for my own needs

[crisp shard]

cool, by extending them do you mean in cpp? i don't do any cpp really, just whena bsolutley needed

[modest crater]

Yes I did, but, not necessarily needed, you can do it with BP but you are really hurting your ability to go full custom with alot of systems if you are just doing bp only multiplayer game

[crisp shard]

yea i've learned the limitations so far as im building a larger open worldish mp game

[tired current]

So I have a question as to why something works vs didint work. I have this setcolorRPC which is multicast call this setcolor function. the OnRep_PlayerColor function contains the exact same code that is not connected after the set W/ Notify node for player color. Using the OnRepNotify works for setting the players color properly to all clients. However if I dont use the OnRep function to execute the code, and simply have it execute after the color is set, the colors of the player only change on the server. Can anyone explain why this is the case? I feel like I am being stupid, but from my understanding multicast should run code on server and all relevent clients?

these are the two dif outcomes btw. With the RepNotfiy both clients have a red and blue player. With no RepNotify and just a multicast the clients are all purple and only the server has a red and blue player. (server is bigger screen)

Is this because the clients player pawns were not relevent? I dont see how this could be as the pawns are ticked to always be relevent, and so are the player controllers.

Any insight is much appreciated!!

[crisp shard]

where is the multicast event being called?

and when you don't use it as multicast, and only repnotify, what do you make tht rpc ? (server,notreplicated,multicast,etc)?

[tired current]

so the multicast is being called from another actor that is owned by the server

[tired current]

Even with the repNotify, It is still a multicast

[crisp shard]

can you show me the event where that rpc is called?

[modest crater]

Don't use them both together, you set the value on the server and it will replicate to clients with OnRep being called if they differ when they arrive

You dont use multicast + replicated and OnRep together

ones for state and ones for events

[tired current]

it is kindof a complex heirarchy. Bassicly the game state spawns this PlayerManager actor, which I assume would be owned by the server. Then it calls an RPC on the playermanager that calls the setcolor multicast RPC on the individual player controller. Bassicly I wanted to have a function that executes on the player and sets it up, so down the road I can do additional setup I might need in this function.

[tired current]

So would Multicast be for states, and OnRep is for events?

[modest crater]

flip it

[cloud crown]

its working but have a bug like for w and s it moves in client left right and a and d left right in server not actually movw but plays animations while transdfering from server to client

[modest crater]

Are you using the CMC or a custom movement component because that looks like it will not predict or replicate nicely at mid to high pings

[cloud crown]

refering to me

?

[modest crater]

yes

[cloud crown]

no

[modest crater]

https://tenor.com/view/water-balloon-cry-boy-child-fear-gif-24749838

[cloud crown]

here

all the logic

[modest crater]

🙏🏼 ✝️

[cloud crown]

lol

[modest crater]

all I will say is - emulate your ping at 50, feel sad for about 5 mins and then pick yourself back up and look into network prediction or look into using the cmc the intended way and watch a youtuber by the name of delgoodie, he has a nice little intro to extending the cmc series.

It will show you some insight as to why you want to do it with client side prediction and corrections in mind

For a non networked game, this would be fine (assuming it works) but for networking its a lot more complex

[twin juniper]

Hey guys, how can a USTRUCT member trigger OnRep? Does it need to have UPROPERTY() or UPROPERTY(Replicated) ?

Let's say i have:

UPROPERTY(ReplicatedUsing=OnRep_Data, BlueprintReadWrite)
FData Data;

USTRUCT(BlueprintType)
struct FData
{
    GENERATED_BODY()

    FData();
    // Identify
    UPROPERTY()
    int ID = 0;
}

How can ID change with trigger OnRep_Data ?

I swear i read about this somewhere but i forgot.

I think only UPROPERTY() is required?

[woeful ferry]

You cant do onrep on struct members

Only on the struct itself

[twin juniper]

Yes i know, i mean how can a change in struct member trigger the parent struct OnRep

[woeful ferry]

??

Because it’s made so any changes to the members it’ll trigger the onrep for the struct

[twin juniper]

But that require that the member have UPROPERTY() on right?

[woeful ferry]

Yes

Any replicated property must be known by reflection

[twin juniper]

How about chain struct though

[woeful ferry]

Same thing there

[twin juniper]

like this

USTRUCT(BlueprintType)
struct FData
{
    GENERATED_BODY()

    FData();
    // Identify
    UPROPERTY()
    FData2 Data2;
}

USTRUCT(BlueprintType)
struct FData2
{
    GENERATED_BODY()

    FData2();
    // Identify
    UPROPERTY()
    int ID = 0;
}

[woeful ferry]

Yea, same thing there

[twin juniper]

Thanks mate

[queen escarp]

hey how do u normally handel "slow effects" with replication ?

since the CMC is not replicated

do u cast to server then rpc an event on every change or ?

[modest crater]

what haha

[meager spade]

is baffled

[modest crater]

You can override the cmc's GetMaxSpeed or you can set the max speed in a way that is replicated, like through a flag so all clients have the same conditions.

The CMC for example has a sprint flag that gets sent with every movement update every frame, if the client was to flip that, when it sends its movement update then when the server receives it, its going to unpack those flags, see the sprint flag is true and that will lead to the MaxWalkSpeed variable being updated to the same as what the clients should have been, thus predicting it and causing no stutters/lag.

And the CMC most definitely replicates btw

[lapis hazel]

hello all! I'm using EOS to host peer2peer sessions (one player host, the others can join). My problem happens when the clients try to travel to the map. I'm using Session->GetResolvedConnectString(FName("TankSession"), JoinAddress); to get the URL but when I execute PlayerController->ClientTravel(JoinAddress, ETravelType::TRAVEL_Absolute); nothing happens. This is the value of JoinAddress (very weird value indeed):

Any insights about this would be extremely helpful. Thanks.

[solar stirrup]

you can just run the open addresshere console command

see if that works

[lapis hazel]

nothing -.-

[woeful ferry]

been a time since i saw that

-.-

[floral sail]

Why on earth RepNotify happens faster than BeginPlay. How is this even suppose to make any sense. RepNotify as I understand is made specifically to help initialize existing actors in the game for newly joined players. But how can you initialize them, if RepNotify function for whatever reason happens right before BeginPlay, making it impossible to affect any components of the actor without a delay or timer.
I can understand why Player State takes some time to fully initialize on Player join, thats fine, but this RepNotify behaviour I simply can not comprehend.

[woeful ferry]

Because when the data arrives, it broadcasts

and that can happen before beginplay

[quiet fjord]

important note in ue5 the serverTravel for packaged games is broken

I don't know if this is happening to anyone else but I have a dedicated server with gamelift and when we use serverTravel to change from the lobby to the game map the server crashes and it happens in all versions of ue5

[floral sail]

Yes I figured that already, but I'm saying that its kinda bad. Sure RepNotify can be usefull for existing players, its easier than RPC (and cheaper too?).
But, as I understand, its main idea is to initialize actors for new players, for example when a new player is joining a session or when it becomes relevant to a player.
And it absolutely no good for that purpose since it always happens before BeginPlay.

[woeful ferry]

Why does it matter, they shouldn't have write access to them anyways

so if they have the values or not shouldn't matter in the context of rep vars and beginplay

[floral sail]

I'm just trying to initialize my Characters. I thought RepNotify would be good for that, all tutorials say that its good specifically for that.

[woven basin]

But your initial character will spawn with the replicated values?

[floral sail]

But I can't Initialize my Character with these values because when they arrive, Character components do not exist yet.

[woven basin]

then if you change them after you spawn, the repnotify kicks in?

[woeful ferry]

then check if they have arrived on beginplay or not

and just call the same initialize function as in the onrep

[woven basin]

are they reliable? I thought if they are all part of the same ActorChannel the order is always correct for that specific actor (when reliable) - i.e. so its components would replicate with the character and that would occur before any RepNotifies?

[floral sail]

Reliable?

[woven basin]

the replicated items for you repnotifies - are they marked as reliable?

cause if they are unreliable - the order is not garunteed

this only applies for the speicfic actor channel

[floral sail]

ok let me visualise my current issue

Screen 1 - Character Pawn (The event is called when Player State is fully initialized (takes some time))
Screen 2 - OnRep function
Screen 3 - Game
Screen 4 - Log

So my RepNotify function for the client will always fail for the existing actors, because it is happening faster than their BeginPlay. Now if a Player 3 will join, then Player 2 will see his name, but Player 3 won't see neither Player 1 nor Player 2, again because of race conditions.

Loop timer helps, but its an ugly solution that I would have to use every time I want to initalize a component, there is got to be a better way.

Hm maybe I over-complicate things. Maybe I should just use BeginPlay as an Initializer rather than rely on OnRep function.

RepNotify ensures that the variable is replicated BEFORE BeginPlay. Well then I guess I can do it the other way around - Initialize on BeginPlay since the value has already arrived.

[woven basin]

https://wizardcell.com/unreal/multiplayer-tips-and-tricks/

read that

it talks about the right hooks to use etc

but fyi - only using BP - your going to have a hard time, yes. In c++ you have more options

[floral sail]

I really wanted to start a C++ project, but the fact that you have to fully recompile after each little change is kinda tilting and repellent

[dark parcel]

you can just do the part where you need C++ in C++ and the rest in blueprint

[floral sail]

Ye APawn::OnRep_PlayerState() indeed looks like a problem solver

[lost inlet]

It's also a crime that by default, there isn't a delegate for the PlayerState being valid on a controller

[dry gust]

Hey guys, is it possible to somehow keep rendering debug geometry when detaching the controller using F8 in a multiplayer game?

I used to draw chunk edges for my world (like in minecraft, when you press F9 ot something..) and it worked fine in Standalone even when detached via F8. But since I started launching it as Listen Server it shows only replicated stuff in the detached mode

by debugging geometry I mean DrawDebugBox() and stuff like that

This whole rendering thing makes sense to me only in the detached mode, cause only there I can see the world from reasonable distance

[woven basin]

just to clarify - it is not a "full recompile" - its just a compile of the changes, which usually is only a few moments because 99.9% of your code+headers have not changed

[floral sail]

Hm. I should try C++ then. Because at this point I feel like whatever discomfort it brings, it can't be worse than not having such features as OnRep events.

[woven basin]

for multiplayer - yes

and like ColdSummer said - you dont do it "all" in c++ - you just hook the main functions and some code, then create BP implementable functions and do the rest there.

but your future self will thank you if you are serious about multiplayer

you can also use live coding - but the recommendation is only do that for function body tweaks. Dont use it when doing header changes etc. So that can also help speed it up.

[stuck glen]

Is there anyone who can help me by explaining how networking works with matchmaking/ battle royale match queuing? From my research I’m assuming you make a server and when a player presses a “join match” button they get sent to a random lobby but I’m not entirely sure

[lost inlet]

I'm not sure what you're expecting as an answer, matchmaking services are usually a backend thing

Either provided by the platform, some thirdparty SDK like Playfab, or a custom service

and that would be connecting over something like HTTP or Websockets, not Unreal networking related

[stuck glen]

I guess that’s what I was most confused on, I’ve never made a multiplayer project, and while I somewhat understand replication, I’m entirely lost on the matchmaking process and didn’t know where to look to make sense of it

[stuck glen]

Thank you I’ll start looking more into it

[lost inlet]

There isn't an Unreal networking part to that, it's a service that ultimately tells you which server connect to, and then you connect to it

The only Unreal thing you might do is use beacons to do something like reserve a slot on the server

[rose turret]

I'm trying to use the NetworkPrediction plugin and going crazy with a linker error on NetworkPredictionProxy.Init. I even removed all of my custom logic to just tame the linker error so the logic is now

    NetworkPredictionProxy.Init<FGenericPhysicsModelDef>(GetWorld(), GetReplicationProxies(), nullptr, nullptr);

and it still fails. the error is

LNK2019: unresolved external symbol "public: void __cdecl FNetworkPredictionProxy::Init<struct FGenericPhysicsModelDef>(class UWorld *,struct FReplicationProxySet const &,void *,class UPrimitiveComponent *)" (??$Init@UFGenericPhysicsModelDef@@@FNetworkPredictionProxy@@QEAAXPEAVUWorld@@AEBUFReplicationProxySet

here's my Build.cs

PublicDependencyModuleNames.AddRange(new string[]
        {
            "Core", "CoreUObject", "Engine", "InputCore", "EnhancedInput", "OnlineServicesInterface",
            "CoreOnline", "OnlineServicesEOS", "SocketSubsystemEOS", "OnlineSubsystem", "OnlineSubsystemUtils",
            "OnlineSubsystemEOSPlus", "NetworkPrediction", "GameplayTags"
        });

        PrivateDependencyModuleNames.AddRange(new string[]
        {
            "Mover", "NetCore", "OnlineSubsystem", "OnlineSubsystemEOS", "OnlineSubsystemEOSPlus", "NetworkPrediction"
        });

and my .uproject has

        {
            "Name": "NetworkPrediction",
            "Enabled": true
        },

any ideas?

[azure hull]

Hi, what are the actual benefits on keeping default ServerUpdateCamera()? I have a topdown game, trying to understand why I should need it. I know that clients are sending camera location to server, but why should I need it? Thanks.

[frosty crag]

Does find session can find session host on a machine not on the same network like a friend's computer ?

[graceful flame]

Yes, but only if you have a subsystem setup properly. If you are using Steam subsystem then I think app id 480 only works if both machines are in the same region. Not sure about EOS restrictions.

[frosty crag]

And if I don't use steam ?

[graceful flame]

EOS

[frosty crag]

What I need to do to setup it correctly ?

what is EOS ?

[graceful flame]

#epic-online-services or #online-subsystems

Read pinned messages for how to get started

[frosty crag]

okk

[worthy portal]

hello guys! I'm struggling really hard with weapon ammo prediction
my previous weapon implementation suffered from ammo counter constantly re-adjusting when ammo variable was replicated from the server to the client, so it sometimes led to pseudo-shots being spawned, when on the client you fire the weapon, but on the server you've already ran out of ammo and shot did not actually do any damage
i thought about implementing CMC-like prediction system for weapons, but i thought that would be really overkill... would like to hear your suggestions for this issue

[woven basin]

This sounds like you are not shooting correctly in the first place.

The client should not, normally, have a different ammo count to the server.

So if that was happening often enough that it was affecting you, sounds like something is wrong with how you are shooting in the first place.

[worthy portal]

ammo is replicated, but when client shoots locally, ammo subtracts locally too

[woven basin]

I understand that, but your example still doesn’t make sense, because it should end up been the same when they stop shooting.

So something is not replicating correctly.

Otherwise how does the server get to 0 before the client in your example above?

[worthy portal]

oh. i don't know how to word it properly, i'm sorry.. imagine firing a weapon, and instead of spending, let's say, 10 bullets, you would spend ~11-12 because it takes time for the new ammo amount to replicate back to the client, so some pseudo-shots are spawning that doesn't hit anything

[woven basin]

Yep. I understand that. But that just means you have a logical error somewhere.

If you client fires 10 bullets, then what does the server think you fired 11-12?

That shouldn’t be occurring.

Anyway, it’s impossible to say what the issue is, as we don’t have your code.

But from a “rubber duck” perspective, you might want to walk through the logic and see if you can work out why the server thinks you fired more than the client. Even with prediction locally etc, that doesn’t make sense

[sudden harbor]

When should you, and when should you not use "reliable" for run on server/multicast events? Can anyone give me an example please?

[pallid mesa]

reliable -> guanratee ordering and arrival (with the exception when the reliable buffer gets filled)

unreliable -> they dont guarantee arrival, so they could be dropped on hazardous conditions

essentially, use reliable for everything that is gameplay critical - ie - spawning a grenade when the player presses a key

and use unreliable for things that dont matter much if they drop - ie: little sparks when the character overlaps with a volume

[dark parcel]

If you shoot fast enough you will see a roll back effect

Because you already subtract your own ammo again before the server comes back to you

The prediction for ammo can be implemented with a counter, that's what Stephen did

I can take a look after work maybe

[hollow eagle]

ammo prediction, especially for fast firing weapons, is actually somewhat complicated. Your client needs to stop firing as soon as you run out of ammo so you do want to predict ammo changes locally to avoid looking like you fire a ton more than you actually are able to, but in doing so you'll find your ammo counter constantly jumping around as you receive updates from the server that are a bit behind where your client is.
One solution is to ignore the incoming server value until you've stopped firing, and only snap back to the server's authoritative value once you know both you and the server have completed firing. With a bit of extra complication to handle the case where you fire again in quick succession.

Knowing when the server has finished can be accomplished with GAS prediction keys or an equivalent - the client sends a locally generated number along with every request to fire. That number is sent back from the server with every change to the ammo count. In that way you can know from the client whether you've already predicted ammo count past what the server has replicated to you.

[dark parcel]

I think it's as simple as you want to update the ammo count to server value when your counter and server counter is the same?

I saw stepgen doing it with a few lines to address the issue

[hollow eagle]

You can't only do that, because you need to correct your value locally if you mispredicted.

[dark parcel]

Yeah I will take a look again, he does have prediction and server rewind for the ammo

[worthy portal]

can you link it please? would also like to take a look

[twin juniper]

same

[woven basin]

its his c++ multiplayer course - I've done it as well - its very good

~~https://www.udemy.com/course/unreal-engine-the-ultimate-shooter-course~~

edit: https://www.udemy.com/course/unreal-engine-5-cpp-multiplayer-shooter/

There are discounts every week on his discord - so dont pay full price - it usually like $10USD etc

but its a bargin, and its very good c++ code styles - i.e. its not like a poor youtube tutorial - the methods aling to many best practices on here. Sure, its not perfect - but its better than most things

[twin juniper]

can anyone buy it for me?

[woven basin]

It says its for UE4 - but it'll work for UE5

[woven basin]

lol - no

[worthy portal]

thanks, will take a look if i catch a discount

[woven basin]

if you cant spend $10USD on a course, perahsp multiplayer development is not for you at the moment. Sorry, but thats the reality. There are many other 'free' choices out there, but the quality varies significantly

[woven basin]

on Stephen's discord - he posts coupons every 2nd week. Defintely dont pay full price - thats just Udemy

[worthy portal]

wait wait wait, i think i once bought some course from him, let me check rq

it was also multiplayer shooter

oh yes, i did, i bought this https://www.udemy.com/course/unreal-engine-5-cpp-multiplayer-shooter/

is it really different? or i can stick to the one i already bought?

[twin juniper]

it's the same but ue 5?

[woven basin]

oh wait

yeah - use the ue5 one

[worthy portal]

no idea honestly

[woven basin]

that's the MP one

i linked the SP one - sorry

[worthy portal]

wow, so i already had one. thats good

[twin juniper]

but fi you bought it, why not just go through all of it?

[worthy portal]

because i bought the course a long time ago, since then a lot has changed for me so i couldn't do games

[woven basin]

yeah - if you have that course - probably need to switch back to it. The best part is, one you do the full course, you can just continue "from there" and build your game from it

and that way you have a solid base to build from

[rustic sapphire]

Hello, I am making an attempt at multiplayer online for a board game i made and I am realizing quite far in that I am making a mess of my architecture ( quite new to unreal. so i am learning as I go. )

i thought I could shove the majority of my game logic in the game mode and now I come to learn clients dont get access to it at all. server only..

Do I need to move all that logic out of game mode to somewhere or do I need to just figure out a way to call to the server from the client to access it?
I have every type of call to game mode in different parts of the code; interface calls, castings, getting and setting variables.
I assume this will be a grind to repair but I am curious what might be some short cuts? (like convert every cast to an interface or add an in between node to make calls out to game mode from a client.

[worthy portal]

definitely will take a look at it again

[twin juniper]

Is it good to buy course or understnad stuff from the base from yourself?

[worthy portal]

thank you all

[dark parcel]

You can just grab the part that you need

Section 184 @worthy portal

[worthy portal]

im on it right now

[rustic sapphire]

Any tips greatly appreciated

[woven basin]

Have you read eXi's intro to networking guide + Wizard cell's tips + tricks from the pin's in this channel?

[rustic sapphire]

a small bit of the links. ill look at that one specifically though.

thanks

[compact flame]

How do I replicate random number in range?

[summer rivet]

you replicate variables, so you put the result of your random number into a variable

or you use seeds and replicate the seed before doing the random

[compact flame]

Whats a seed?

[summer rivet]

look at random numbers from streams

but getting the random number on the server and replicating a variable is probably smarter

well using a stream or normal random and doing that, syncing the seed then using from stream would be fine as long as every action is synced

[compact flame]

This is how I have it setup rn

It does not seem to work

[summer rivet]

what doesnt work?

[compact flame]

The random num gen it only gens on server

[summer rivet]

well it runs on the server, sets the variable, then the on rep runs for it

inside the on rep print out the random number and see what shows it printing. it should be all clients and servers

[compact flame]

ok

Its not doing the client

[summer rivet]

so what do you see printed out

[compact flame]

Printing it 2 times

[summer rivet]

so what is this setup? listen server, dedicated server, how many clients?

[compact flame]

Im playing as client I only have 2 screens its printing 2 times cuz I wanted to be sure.

[summer rivet]

?

what are those set to

[compact flame]

Client num of players 2

[summer rivet]

so a dedicated server with 2 clients

[compact flame]

Yeah

[summer rivet]

and what calls this code to run?

[summer rivet]

and what is bp_breaker? is it spawned in, is it in the level at start?

[compact flame]

Yeah ill take a pic of it in level

[summer rivet]

so im curious, since random num is exposed set it to something in the level and what does it show when your event runs

[compact flame]

Ok

Give me a couple min im loading OBS then imma compress vid

I added a delay and made the num -1 every sec

cuz I forgot that part but that has nothing to do with my prob so that is of no use only reason im saying I did that is so you know I canged code a bit

[summer rivet]

so is the default for randomnum set to 6 then?

[compact flame]

Yeah

[summer rivet]

ok so i want to know why server is firing twice

it should be server, client, client

[compact flame]

Cuz im printing 2 times

[summer rivet]

assuming your print strings are in the onrep_randomnum

why are you printing twice?

[compact flame]

Yeah and at tick

[summer rivet]

show the on rep code

[compact flame]

Ok

[summer rivet]

no I mean that first interact shows serverx2 and both clients, which doesnt make sense

[compact flame]

Weird

O

I got rid of the print on interact

no 2 servers now

js 1

[summer rivet]

oh... didnt know you had another print..

[compact flame]

Yeah one on interact

my code is messy lol

[summer rivet]

what is changing your code down every second?

[compact flame]

Wdym

[summer rivet]

you said you added a delay and are making the number -1 every second

what is calling that

[compact flame]

Tick

I have a branch if Random num is <=0 then -1

with a delay of 1 sec

so its not instant

[summer rivet]

so..

was that code running before at all?

[compact flame]

One changes color

[summer rivet]

because if your doing that on the client side, its going to overwrite any rep from the server

[compact flame]

Oh?

[summer rivet]

well I mean if your not gating your code, which im guessing you arent, each isntance of the blueprint will run. one server, one client 1, one client 2

and then your server will update the number and try and rep it to the clients, but the clients will also be changing it (locally)

[compact flame]

Yeah but even when I first gen the num it is not the same on client

[summer rivet]

which is why I was asking if anything is updating the number somewhere else thats not ran on the server

[compact flame]

Uhhhh

[woven basin]

you are multicasting?

[compact flame]

This is all my code minus the custom event

No

[woven basin]

you sohuldnt be multicasting that

[compact flame]

Sorry I js names it that

[summer rivet]

yeah its just named that...

[compact flame]

I was at first but changed it

and didnt feel like changing the name 😅

[woven basin]

you probably want to break that habit early - cause its crazy confusing

and a sign of why we're having trouble helping here

[compact flame]

Fair

Changed it

Lol

I usually dont do that but I wanted to fix this replication issue first

[summer rivet]

ok lets eliminate the weird possibilities

duplicate this

[compact flame]

ok

[summer rivet]

and unhook your tick

the on rep is what you expect, just printing

this should get you the same result in both windows

we have to ignore the fact that there is a bug that prints all clients as Client 0... 😦

[compact flame]

It does not seem to be printing anything on play

hmmmmm

[summer rivet]

well then thats weird lol

[compact flame]

Yeah lol

[summer rivet]

cant really mess this one up assuming thats the item in the level and uh.. its all hooked up

[compact flame]

Yeah

Should I make another blueprint

to test

[summer rivet]

you could but that wont help fix this issue. maybe show the code now?

[compact flame]

cuz this one might be bugged or sum

[summer rivet]

its possible the on rep is bugged, which is what I was testing with this

F9 on the blue node where you call the randomnumberonserver, see if it triggers a breakpoint

[compact flame]

It does

What is a breakpoint though? Is it usefull?

[rustic sapphire]

do blueprint interface functions or function library functions need to have some sort of replication setting? or is it best to just have them point to a server only / client only function?

[summer rivet]

well it lets us know the code is running

[summer rivet]

do the same thing on the set with notify, and remove the f9 from the first one

[summer rivet]

so now we know the code is running but is it running the RPC on the server

yep so it should print if your print code is good?

[compact flame]

This is so weird

[summer rivet]

assuming you filled out the on rep lol

[compact flame]

Wdym

[summer rivet]

well I mean you added the print string to the onrep_testnum function?

[compact flame]

uhhhhhhh

I did now lol

[summer rivet]

cant see any prints strings if we dont have any lol

can probably remove the F9 now

[compact flame]

😂😂

Fair

Its only showing server

Nvm

Now its showing nothing again

Greaaaatttt

[summer rivet]

change the print string duration to 10 seconds in the onrep

and then try again

see if it only every shows server: random number and never shows clients before it goes away

[compact flame]

We back to only server

[summer rivet]

so only shows server for 10 seconds, which is enough time for the clients to show up on your screen?

[compact flame]

Yeah

[summer rivet]

ok so.. is the actor set to replicate?

should be net load on client and replicates

[compact flame]

I set actor to replicate and now it both shows up

It replicates corectly now 🙂

Is that it?

[summer rivet]

el oh el

yeah try hooking your code back up

[compact flame]

Alr

[summer rivet]

I should have checked that first but.. live and learn

it makes sense and since you had other code, outside the on rep, printing its why we saw the other values since it was the local things doing the printing and not the on rep from the server

hopefully it works now

[compact flame]

It works 🙂 Thank you very much!!!

[summer rivet]

yeah so something important to learn from this I guess, your thingy needs to replicate if you want it to replicate across the network

if you didnt have the variable, it would have been fine but the variable wanted to replicate and your actor was like "Im not allowed to replicate, so you cant replicate either"

[compact flame]

Yeah

[vapid gazelle]

How does one correctly handle Character's Launch Character node in a multiplayer context?

Say I'm doing a wall jump. Calling Launch Character when the player is the server works great, but doesn't work if the player is the client, unless I make a server RPC that then calls Launch Character on my behalf. I'm used to character movement being typically replicated on my behalf from the client, so this is new to me.

I'm assuming that doing something as timing-sensitive as a wall jump is probably best predicted on the client if there's sufficient latency, while also making the call to the server in parallel? I'm not entirely sure how to reason about this. Any tips?

[rustic sapphire]

looking through these compendium and maybe I missed it but does the level blueprint exist on clients as well? Im looking to move my game mode logic somewhere that client can call

the logic is tied to actors in the level but it is mostyl math and other backend logic

[icy jetty]

You shouldn’t be using the level blueprint regardless

No bp can communicate with it

[halcyon ore]

This specific case could be different.
But, just trigger both.
Client -> launch -> ROS
Server -> launch

If they have the same exact data, they should end up at the same, or very similar spot, so no lag is felt.

Thats how input/ movement in general works, to have no direct latency, but also not allow the client to phase through walls.
Its just all wrapped up in a couple functions you call, for normal forward, back, left, right input

At its core thats how they work.
Client does input, then tells server to do input.
They compare locations, and undo/ forcefully adjust server side as needed

If client didn't do the input, and just told server to do it.
It'd work.
But, even a couple ms of latency would be aids.
I once made a custom camera system, but didn't replicate it properly (server did all the edits, client didn't do its own edit)
It was goofy.
Spin mouse.
0.1 second later, your camera moves.

[vapid gazelle]

Huh that actually works way better than I expected, thanks for that suggestion. I tried it even with these settings and it's pretty responsive on client-side, with the occasional rubber banding to some other location, but in theory it should be perfectly deterministic on both ends.

[vapid gazelle]

Glad that's handled for us already

[halcyon ore]

TBF, thats just basic replication.

Server overrides client.

The movement component just is a bit more nice with it, within limits.

[tired current]

If I were going to play say a gunshot sound at the location of a clients PC, and wanted it to play on the server and all other clients, how would i achieve this? Multicast only works if it is the host client, and run on server only ever plays for the host client.

I feel like doing some weird rep-notify thing with a bool for play sound or something is not the best way to handle this.

[vapid gazelle]

Fair enough!

[halcyon ore]

Have the server call a multicast event.
and, if your an owning client, then call to the server, then the server calls a multicast event

[rustic sapphire]

Oh good to know so then gamestate would be better for a controller to call that can also query a different client?
Does the size of the controller matter in the end? I’m trying to obscure direct access of logic from a player (thinking about cheaters)

[tired current]

so I would need a seperate actor like an audio manager owned by server to handle playing the sounds for a client that is not the listen-server?

[halcyon ore]

No?

Assuming this is some sort of gun.
have the holder of the gun call to server, then servers calls multicast

The server owns everything.
It can do whatever it wants, whenever it wants.

[tired current]

sorry could you elaborate on "call to server"? Should I check for authority and if actor has it it calls a run on server rpc and if its a server it calls a multicast rpc?

im a bit new to multiplayer

[halcyon ore]

call to server
run on server
ROS
Whatever you wanna call it.

[tired current]

ahhh okay thank you

[compact plume]

What's the most consistent way to implement a moving platform that players can stand on in a high latency case? Seems like the tradeoff is either have the platform jitter (implementation is based purely on the actor mesh movement replicating) or have the simulated proxies jitter from server corrections (implementation is deterministic with forward-ticking the platform to account for ping)

bServerAcceptClientAuthoritativePosition doesn't appear to help the latter case either

[saw some discussion about it here but looks like there wasn't any explicit solutions uncovered](#multiplayer message
)

[icy jetty]

Not sure about all that but GI might also be an option

[thin stratus]

Moving Platforms will always require based movement. Based Movement ensures that server and client only compare relative locations to the Platform and not world Location, cause the Platform will never be in the same place for server and client.

The only additional thing that you need to provide is smoothing of the platforms location on the Client, because just replicating movement will have it lag. And if it lags it will cause problems

[compact plume]

Gotcha -- for the smoothing of platforms on client i think the forward-tick by ping amount should work (with some regular sync'ing there for jitter purposes).

Anything you can direct me to for using Based Movement on the platforms? I see some references to this in CMC w/ ReplicatedBasedMovement but not sure where to go for adding this to the platform

[thin stratus]

In theory this is automatically handled as long as both sides can resolve the platform

[compact plume]

hmm. so basically when im setting up the platforms to be deterministic w/o movement replication, such that the client is forward-ticking by their ping, i still get issues from CMC network corrections.

but the platform itself is in sync now, and i know that because if i jump on the client its just a vertical jump up and down. but if i do this w/o the forward-tick to account for the lag, then when the client jumps they teleport to the side and back in midair, which makes sense since thats where the server character is

(this is all with like 150-200ms lag)

so this leads me to believe the issue lies on CMC, no longer the moving platforms themselves. but i could be totally wrong here...

[compact plume]

ah ok after digging into this a bunch more i think i have a path forward -- smoothing of the platforms is handled by just having movement deterministic based on start time (no need to forward tick)

and then if i can somehow get the character to still be BasedMovement while its in midair after jumping off the platform, i think that resolves it -- perhaps just forcing based movement if the character is overlapping in a volume over the platform

[fervent leaf]

On C++, is the only way to launch OnRep's on server is by calling it manually on the server? As I heard, there might be cases where the variable might not actually have been changed and ofc the manual call still will happen? Or is it actually how epic games recommends doing it?

[thin stratus]

Why do you need the "above platform" part?

Do you want the Platform Velocity to be taken into account when jumping?

--

Anyone here with NetworkPredictionPlugin and NetSerialize knowledge? I have some stuff I can't find anyone for to discuss with.

[compact plume]

if the client jumps up and down on the platform while its moving, the server applies corrections while in midair because MovementBase becomes invalid

so in midair they teleport in one direction, and then land back where they were on the moving platform

[thin stratus]

In theory, OnRep is meant for Clients only, to be notified when the Variable replicated, and then optionally call if the value is the same.

If you have logic in there that should also call for the Server, then you'd call it manually in the Setter of your Variable. Given you know if it changed there, you can simply choose to not call it if the value is the same.

[thin stratus]

Hm, makes sense I guess, cause the RelativeLocation is based on a not-synced BasedLocation

[compact plume]

open to better solutions though 🙂

[thin stratus]

I have to figure out BasedMovement for Mover soon anyway, so I will face that problem too.

I always wondered how that is solved hm

[vital furnace]

Hello, i want to know how to logout a player who reach lobby after i reach maximum player in server, how can i do that in OnPostLogin with blueprint ?

[thin stratus]

Only Blueprints?

You could actually try to make UE already do that for you, even in Blueprints, without any "After joining" logic.,

Is the amount of players for the Lobby fixed from the point that the Server opens the Lobby with OpenLevel?

[compact plume]

im too nervious to switch away from ACharacter right now so waiting for Mover to get fleshed out more 😬

[fervent leaf]

But if i set variable on server function which launches the onrep on the client and after that, i just call the OnRep and it makes it just a normal function call, on the server only. So i just think should i try to prevent doing this or is it fine in this situation.

As i just think this would be the most simple way

[vital furnace]

yes

[thin stratus]

void AFooBar::GetLifetimeReplicatedProps::(TArray<...>& OutProps) const
{
  Super::GetLifetimeReplicatedProps(OutProps);

  /// Only calls OnRep on change (same as regular DOREPLIFETIME)
  DOREPLIFETIME_CONDITION_NOTIFY(AFooBar, Bar, COND_None, REPNOTIFY_OnChanged);

  /// Calls OnRep even if the Value doesn't change
  DOREPLIFETIME_CONDITION_NOTIFY(AFooBar, Foo, COND_None, REPNOTIFY_Always);
}

void AFooBar::SetFoo(const int32 NewFoo)
{
  if (!HasAuthority())
  {
    return;
  }

  if (Foo == NewFoo)
  {
    return;
  }

  const int32 OldFoo = Foo;
  Foo = NewFoo;
  OnRep_Foo(OldFoo);
}

void AFooBar::OnRep_Foo(const int32 PrevFoo)
{
  /// Call on Server and Client only when changed
}

void AFooBar::SetBar(const int32 NewBar)
{
  if (!HasAuthority())
  {
    return;
  }

  const int32 OldBar = Bar;
  Bar = NewBar;
  OnRep_Bar(OldBar );
}

void AFooBar::OnRep_Bar(const int32 PrevBar)
{
  /// Call on Server and Client even if same Value
}

@fervent leaf

[vital furnace]

yes

[thin stratus]

That ignores the concept of Property Replication that says that only the latest update is ensured to arrive on the Client of course.
If the Server changes the value from 2 to 3 to 2 in a very short time (e.g. same frame), Client might not get that update at all.

[thin stratus]

Then try to pass ?MaxPlayers= with the OpenLevel command, in addition to the ?Listen param and specify the actual number behind the =.
You can use an Append Node to set the value to something dynamic in case the Player can choose the size.

UE should then already deny the connection automatically.

[vital furnace]

Please show me

[thin stratus]

I'm not so keen on shoving pictures of nodes into you. What are you struggling with?

[thin stratus]

You should 100% not touch Mover atm, if you don't have the ability to utterly rework NPP and Mover a lot.

Our Internal NPP version is so damn changed by now

I'm honestly annoyed at it.

[compact plume]

fair enough, that's probably beyond my willingness to tinker with this stuff right now

[fervent leaf]

Thanks, makes sense.

[thin stratus]

It's beyond mine too, but well

[hollow bridge]

Is that true that GC "Reachability Analysis" is not done in gamethread in shipping builds? because I see huge spikes in my dedicated server not sure how can I profile shipping build

[compact plume]

hmm i was testing a fix with overriding CMC::FindFloor but that didn't seem to entirely work. it does have some effect on the BasedMovement, but not entirely what i'm looking for

to make more concrete, that's the issue i'm trying to resolve -- server applies corrections as soon as client jumps in the air (and is no longer Based Movement), and then undo's those corrections upon landing back on the Movement Base

best lead i've got is temporarily enabling bIgnoreClientMovementErrorChecksAndCorrection on CMC while on the platform, but if you're on the platform long enough then there starts to become noticeable desync in position

[thin stratus]

The problem is that the Server and Client only align due to the RelativeLocation. You should also have a correction when initially landing on it, in theory.

At least that's what I have on Mover. Not sure how exactly that translates to CMC atm.

Somewhat assuming they didn't reinvent the wheel.

[compact plume]

yeah ideally what i was trying to accomplish with custom CMC logic for FindFloor was to just not lose RelativeLocation while in air, and persist the BasedMovement. but that didn't pan out

seems overly complicated just to get this client-server sync on a moving platform argh

[thin stratus]

@compact plume

    static float ClientAuthorityThresholdOnBaseChange = 0.f;
    FAutoConsoleVariableRef CVarClientAuthorityThresholdOnBaseChange(
        TEXT("p.ClientAuthorityThresholdOnBaseChange"),
        ClientAuthorityThresholdOnBaseChange,
        TEXT("When a pawn moves onto or off of a moving base, this can cause an abrupt correction. In these cases, trust the client up to this distance away from the server component location."),
        ECVF_Default);

    static float MaxFallingCorrectionLeash = 0.f;
    FAutoConsoleVariableRef CVarMaxFallingCorrectionLeash(
        TEXT("p.MaxFallingCorrectionLeash"),
        MaxFallingCorrectionLeash,
        TEXT("When airborne, some distance between the server and client locations may remain to avoid sudden corrections as clients jump from moving bases. This value is the maximum allowed distance."),
        ECVF_Default);

/** Property to set if characters should stay based on objects while jumping */
UPROPERTY(Category = "Character Movement: Jumping / Falling", EditAnywhere, BlueprintReadWrite)
bool bStayBasedInAir = false;

/** Property used to set how high above base characters should stay based on objects while jumping if bStayBasedInAir is set */
UPROPERTY(Category = "Character Movement: Jumping / Falling", EditAnywhere, BlueprintReadWrite, meta = (editcondition = "bStayBasedInAir"))
float StayBasedInAirHeight = 1000.0f;

They do a lot of stuff to allow the Client to in the air for a bit before corrections come back

There is a lot of code in UCharacterMovementComponent::ServerMoveHandleClientError that handles this exact case before it actually compares Server and Client Location.
It seems to modify ServerLoc a lot to bend some rules for these corrections to not be that bad.

[compact plume]

oooh these are super helpful, thanks!

looks like StayBasedInAirHeight might be what i want, but not seeing that in 5.3. might be new to 5.4?

[thin stratus]

I don't think it really resolves the issue over all. It just improves it.

Could be, yeah, the engine is 5.4 where I got that from

[compact plume]

yeah well in the case i have where it applies the correction and then removes it, the client starts and ends on the base. so i think that actually does solve the case

its kinda similar to what i was trying to hack around earlier by having a volume / overlap box over the moving platform where CMC properties would get modified lol

[thin stratus]

I think the initial correction when landing on the platform causes the problem over all

If the Server tells the Client that the RelativeOffset to the Base is wrong and forces the Client to keep the same offset (so they are relative to the center of the platform on both sides), then when jumping off of the platform, it will have the wrong world location.

It almost feels like it would be simpler to increase the correction threshold on based movement

[compact plume]

true, but that initial correction does keep the client + server position on the base itself in sync despite lag -- without that the relative offset would be different

[thin stratus]

Yeah, and I think that might be fine

That they are not in sync on it

[compact plume]

i guess its a tradeoff of where we want the "desync" to happen

[thin stratus]

Yeah

[compact plume]

yeah

only problem tho

if the desync happens, then a client might fall off platform while server char is still on it. or vice-versa

[thin stratus]

The problem is, let's say you walk off the platform. The edge of it will be different. But if the edge is the same, you get the correction anyway due to world being different.

[compact plume]

not sure i follow

oh you're saying it'll correct as soon as the client starts falling off in midair?

that would probably be more visually jarring i think

[thin stratus]

Doesn't matter if the Base is ahead or behind

You kind only have these two cases. You are either keeping world align, and the relative is off, or you keep relative aligned and the world is off.

If you Jump in case 1, you won't get a correct.
If you Jump in case 2, you will get corrected to the correct world location.

[compact plume]

ahh yeah

[thin stratus]

If you walk of the Edge in case 1 (the edge to the left in the screenshot), you'll get a correction in both cases.

Case 1: Server reaches the Edge first and starts falling, causing client to have a different base and be forced to falling.
Case 2: You both start falling but the client gets the corrected world location.

Now the CMC has these variables and stuff to allow the Client to be authority in specific cases, but I don't see the gain yet.

Let's assume Case 2 is what we are going with. If the Client jumps and remains Auth over its position offset during falling, as soon as they land they would be corrected.
And even with the code that allows some offset when landing, eventually sou need to sync them back.

And to get to Case 2, you need to correct the Client when landing on the Platform.

[compact plume]

this may be overly optimistic, but if the variable allows some offset when landing on base, and the client-server relative location is intended to be synced but its within that difference, then walking off edge should minimize a partial amount of the distance

i guess as to "reduce" the correction distance

[thin stratus]

Yeah

[compact plume]

although p.ClientAuthorityThresholdOnBaseChange 5000 in console is still causing corrections to happen lol

[woven basin]

So can I ask - based upon your significant expertise with UE and multiplayer, and clearly you know the CMC inside out - have you realised any benefits of using Mover? Has it actually given you anything that you couldnt have achieved with CMC?

[thin stratus]

Sync between Mover and other Simulated Systems

[woven basin]

as in GAS prediction - i.e. staminia?

or "other" simulated stuff?

[thin stratus]

Not GAS. GAS can screw off.

Weapon System for example.

[woven basin]

lol

so having a weapon means having a GameplayTag to slow you down if aiming, and you use that for Mover?

[thin stratus]

For example, yeah. But also being able to fully rely on Locations, Aiming, etc.

[woven basin]

and if you take an example of been shot causes you to "stun" for 0.2 second or something - Mover is able to handle that ok with prediction etc which is easier than with CMC?

[thin stratus]

Being shot and stunned will still be a correction

[woven basin]

cause client will always be a few ms behind server to know it got shot?

[thin stratus]

Yeah, you can't predict other players

[woven basin]

yep yep

[compact plume]

confirmed the 2 stay based in air properties are introduced in 5.4 -- i think at bare minimum these will help reduce the overall number of corrections to just when entering/exiting the moving base

[compact plume]

and i'll debug this more tomorrow -- 430am now, gotta sleep.

@thin stratus thanks for the discussion and help here, genuinely really appreciate it a lot!

[thin stratus]

No worries

[azure hull]

Hi, it looks like GameplayTags from GameplayAbilitySystem take quiet a lot of bytes when replicating, has anyone noticed that and what are the opposite approaches of sending them? I get that GameplayTags are basically FName and FName is quiet heavy over a network, but I wonder what are the better approaches here? Like running GameplayCues or GameplayEffects, their tags are filling up packets. Or am I missing something?

[woven basin]

If you pre-register GameplayTags in c++, it should be super efficient with FName bytes?

[azure hull]

You mean pre-register with definitions like UE_DEFINE_GAMEPLAY_TAG_STATIC? Or what do you mean by pre-register?

Because all I do, is I make a tag in GameplayTags manager in editor, then in C++ define with UE_DEFINE_GAMEPLAY_TAG_STATIC and then pass it to GameplayCue or GameplayEffect executions (I assume this is the part that make these tags expensive, not BP GameplayEffects or GameplayCues).

Hard to figure out witch tags are the issue, either from UE_DEFINE_GAMEPLAY_TAG_STATIC or used ones in GE/GC BPs.

[woven basin]

I’m going to defer to one of the smarter people in this channel. I have some theories but I don’t want to spread false info. All I know is gameplay tags are considered super efficient…

[gilded vapor]

Are you sending them as individual tags or gameplay-tag-containers?

[sinful tree]

FGameplayTag are 12 bytes but can store essentially more values than you would ever want to have to type out. A similar type would be Enumerators which are 1 byte but can only manage 255 values which may not be enough and that means having to use multiple enumerators to represent the values you want, but now each flag is only 1 byte rather than 12.
If you were really concerned with network usage, you could use bits within a byte for flags, thus allowing you to use the full 8 bits of a byte each representing a unique flag. 12 Bytes could now represent 96 potential values instead of the 1 single one you'd get with an FGameplayTag or the 12 you'd get using Enumerators.

How to best handle it then? Still use GameplayTags in your normal logic, but when replicating things, you'd serialize them into bits before sending them over the network, and reconstruct the bits as GameplayTags on the other side, but I would only go down this path if it was something very network hungry like replicating stuff on every frame, otherwise it's probably a bit of a pain to have to set up and add more values as you need them, and it's trading CPU and a bit of RAM for bandwidth, but it is an optimization you can utilize. But here's the thing.... If you properly utilize FGameplayTagContainers, I can guarantee you that the engine is likely already doing something like this as Epic themselves use FGameplayTagContainers for almost everything in GAS.

[azure hull]

I'm using a single FGameplayTag. Here one of the GameplayCue executions.
.h

    UPROPERTY(EditDefaultsOnly, Category = "Gameplay Ability Damage")
    FGameplayTag GameplayCueTagTargetCore;

.cpp

    FGameplayEffectContextHandle Context;
    for (const FActualHitResult& ActualHitResult : ActualHitResults) {
        ActualHitResult.AbilitySystemComponent->ExecuteGameplayCue(GameplayCueTagTargetCore, Context);
    }

[azure hull]

From this optimization I don't think that my solution should take so much, probably just a poor implementation of GameplayCue execution or GameplayEffect execution.
But thanks a lot for detailed explenation of possible optimization, will keep this in mind. But first might need to try out FGameplayTagContainers, as you @glossy iron and @gilded vapor both mentioned it.

Used FGameplayTag not container because this function asks for it.

I'm manually executing GCs this way, so that I could have benefit of caching when they all executed in one frame. I'm doing similar thing for GEs.

[gilded vapor]

I haven't used GAS in a while but aren't cues usually batched in with events

IE you generally don't manually replicate cues because another system replicates them for you

[charred sapphire]

Hey guys!

I've started learning multiplayer recently, and I don't really get something.

I have the attached blueprint in my PlayerController. The behavior I'm not understanding is that the highlighted OnPosess and OnUnPosess events only get triggered on the server, not on the client. Is that correct behavior?

Any tips on how I can make this attaching-removing UI behavior work in that case?

[azure hull]

I'll have to check, haven't really dived into it too much.

[azure hull]

Most likely, initially I had these executions in GEs (when GE executed, it performs GC), but then caching was not properly utilized when there were 50+ GC executions in a single frame. But now I'm just trying to figure out all this GameplayTag thing in Network optimization.

[gilded vapor]

ngl that sounds like you are trying to spawn wayyy to much vfx/sfx in a single frame. You'd probs want to batch some of those effects into a single cue

[azure hull]

It happens when player hits many targets with one attack (like in ARPG scenario). For it to look responsive to a player all these effects are performed all at once in a single frame. Using caching & Niagara Data Channels it performed well. All that's left is to figure out Tag networking optimization in this case. But I'll have to look into alternatives, thanks!

[red thicket]

Has anyone here rolled out custom motion in multiplayer without GMC? Climbing / sliding / creature movements etc?

[tardy fossil]

i made my own completely custom network movement without using the CMC or Mover... it was not easy lol

[strong vapor]

well then let me ask you this good sir..
how would you handle interpolating MaxWalkSpeed based on velocity..
I already made some custom client prediction and custom SavedMove stuff.. and the sprinting part works great.. but my company, they want things to feel real organic.. they want it so when you run up to a cliff edge you gotta pull back on the controls to slow yourself down.. and everything I've implemented works great on the server.. but man.. the pullback jitters so hard.. I'm using GetVelocity.Size() to interp..
what else can I mess with in the CMC? lol

I've messed with all the network values and given them obscene values.. and it still jitters..

[thin stratus]

You wouldn't really use MaxWalkSpeed for that, but rather different Acceleration and Deceleration values in CalcVelocity.

[woven basin]

https://www.youtube.com/watch?v=RtQRMcupJs0

that teaches you everything you need for what your asking

[strong vapor]

well I was originally using Acceleration.. but didn't really find any variable to tweak for deceleration

ho man, thanks for the tutorial link! will watch that in a bit

so I should override CalcVelocity, righteous

I just this week started doin the deep dive into overriding things in the CMC

so it's all pretty new.. kinda hard to believe I'm this many unreal years old before learning this stuff

[strong vapor]

so it sounds like you're thinkin its totally within the realm of possibility to be able to adjust acceleration and deceleration without having network jitters

[thin stratus]

As long as both server and client have the same info, yes

[strong vapor]

well.. soo.. I've been using GetVelocity to calculate things and interp my values... and GetVelocity probably will be different on the server and client a lot of times.. is there anything better I can use? like maybe some stuff in the move predict data?

I'm lookin at the source as we speak, just a lot to take in..

just so I understand this right.. the part of CalcVelocity that's assigning values to Velocity.. that's what's actually doing something to our movement, right?

[thin stratus]

This calculates the velocity that is later applied.

[rustic sapphire]

Not a clue if this is a dumb question, if I make an online game either for mobile or desktop, do I need to be adding security features in my game for players to not get hacked or is that something that either doesnt/cant happen or is it handled somehow by unreal?
ideally, id like a steam account/switch profile/apple game account/ etc to just connect to an entrypoint for things like rankings and then name and icon and nothing more.

[oak pond]

uuuuhh should I be worried that my game is basically unplayable even with just Average emulation?

I dont think I could be doing anything much better than I currently am, theres nothing too bad, other than I guess replicating my players aiming value every frame because I have no idea how else to do that

I mean realistically, if I just make my game and set up multiplayer properly and everything using the steam system, then get it into steam, isnt there still a chance itll just be incredibly laggy out of my control? like what determines how well it will work beyond physical distance between clients

[dark edge]

Yes

What's the problem?

Multiplayer is hard

Test with average or bad net conditions from day 1.

[red thicket]

I think there’s a way to factor in that difference, there’s a great playlist I’m watching about the CMC that touches on this discrepancy

https://youtube.com/playlist?list=PLXJlkahwiwPmeABEhjwIALvxRSZkzoQpk&si=LsZNtQSBsHQLgrI0

[oak pond]

but even just jumping is broken. how could I have gone wrong there?

literally the only thing that isnt completely broken is just running around which is only because its default character movement. the second I use a dash or jump theres a huge teleport or delay, firing the weapon has at least half a second delay

and these are all one off things, just simple server to multicast events

[strong vapor]

nice! I watched the third video to get the SavedMove stuff in there.. I'll watch through the rest!

[red thicket]

Not saying you need this plugin (it’s crazy expensive and it’s possible to handle with C++ though I don’t know how difficult yet) but wondering if you’re running into the same problems as this guy

https://youtu.be/YB_ew3j_HFw?si=PfihaS0mYk5GZmSH

[oak pond]

yeah I saw this before, looks great but I do NOT have that kinda money lol

but I dont think basic movement mechanics should be falling apart on average emulation

[red thicket]

Are they basic movement mechanics or are they custom movement mechanics?

The built in CMC movements should replicate and interpolate without crazy jitter

If you get into custom movement I think you have to dive into the C++ and extend the CMC or make an even more complex solution

[oak pond]

yeah as I said the movement is fine but its my jump and dash (which are mostly just launch character)

[red thicket]

How did you implement these (broadly speaking)?

[reef bison]

it's very easy to implement this stuff wrong in a multiplayer context so it's not a surprise that it isn't working well if you haven't been testing the game with latency since day 1

[oak pond]

its mainly just play montage + launch character (and some other movement component settings that need changing for the dash)

but again, what could I even be doing wrong. its just individual one off standard events

[reef bison]

theres no way to know whats wrong without an example

but simply dashing the player with a server event is already bad because they will notice the latency

[oak pond]

yeah I think I noticed that I had to have jumping on server as well as a non replicated event

Im perfectly happy with any way that I can let the player move freely then just have the server try to replicate it as best as possible on the other players ends. Im not really worried about cheating as this is co op but I think that will make enemies a problem

[oak pond]

but uh yeah even this still has problems

[oak pond]

realistically as someone who just cannot learn c++ or any form of coding beyond blueprints (believe me, Ive tried) and probably wont be getting any other help with this project, should I even be trying co op multiplayer? Im always so determined to try but it just doesnt seem doable

like even with how difficult it is to get working at all, as far as I knew Ive been doing everything right and its still unplayable anyway

[oak pond]

also, steam p2p hosting definitely doesnt require paying for servers right? if theres no free option at all then I will know that I can just save myself the effort and quit working on mp right now (I know the steam page costs of course)

[kindred widget]

To be clear. Steam doesn't host. Steam matchmakes. And the only fee is having your game on Steam for the 100$. Or using the testing app code if you're not that far. There isn't a fee beyond that for using their session searching services.

[oak pond]

yeah, thats what I was thinking, p2p player hosted servers using steam accounts

[tired current]

If I wanted to call a function from a server owned actor that would only run on a specific client how would I do that?

[thin stratus]

Run it on a ClientOwned Actor of that Client

[red thicket]

Will help to know more specifically what are you trying to do / what obstacles you’re facing @tired current ?

[twin juniper]

Interact --> Server RPC --> Verify that it's good --> AddItem to inventory array which is replicated --> How to update the client Widget?

I need help with the last part, where I want to be able to update the client ui

[reef bison]

OnRep on the inventory array then broadcast the change to the widget

[twin juniper]

Wouldn't that fire the function on all clients? (I only want the owning player, knowing that this code is in a component in the player character)

[reef bison]

you can use DOREPLIFETIME_CONDITION and COND_OwnerOnly if you only want the owner to receive the replicated values

[twin juniper]

will the array still be replicated for everyone?

[worthy oak]

Which do you want owner only or everyone getting it lol.

[twin juniper]

I dont know anymore

people are telling me that the array shouldnt be replicated at all

[worthy oak]

Probably shouldn’t be

if it’s multiplayer

[twin juniper]

it's multiplayer ye

so everything should be client only and when some do a trade, what happen?

#cpp

[worthy oak]

No?

I mean you likely want your inventories to be on the server

The server keeps track of everyone’s inventories

you can then tell clients what their inventories look like for UI

[twin juniper]

Everyone are telling me different stuff... That's confusing

[worthy oak]

They aren’t

It’s the same information

[twin juniper]

the server is a client btw

I talk about the other type (forgot the name)

[worthy oak]

and a listen server is still a server. You just have a server and a client on the same machine

[twin juniper]

wait so how would I onlky store an array of items for each player on the server?

that's already what I have

that's not on the server lol, all clients have their own array

so you are telling me it's already on the server?

So I would attach the inventory component to the game mode (where the server is the only one existing)

that's already what is happening

but it's there for everyone... (not server only)

I want to do what you are telling me but I dont fully understanding how I would replicate for the server only

Wait, I understand, the server would know everything in the world, the player couldn't unless they do a server RPC, since the array will not be replicated, I now need to find a way to use the RepNotify without replicating it fro all clients for the UI property..

I thought a repnotify meant that it's replicated

and that only fires on the owner?

That's so good

there's only 1 guy that should receive it

the guy that tried to pick up an item.. right

'the actor's owner'

ye

ofc, the player is client owned

[sinful tree]

I think what you're misunderstanding is that replicated actors and properties are basically copies from the server. When you have a replicated actor spawned on the server, the server tells the clients to spawn that actor on their end as well, and also tells them any replicated properties that the server has.

If you have an inventory, and you want players to know about what their inventory contains, you normally rely on the server to tell the clients that information, otherwise you're relying on clients to tell the server what is in the inventory which can lead to cheating. Like I can tell the server I picked up a +9999 Damage sword and equipped it and if the server just accepts that, then that's what'll happen.

[twin juniper]

by replicating the entire array, anyone can change the array and the server will also take that change as nothing happened?

[sinful tree]

No

Replication only happens from server to client.

Clients can change any data they want on their end, but unless the server changes it, the server is the actual source of the information.

[normal viper]

You would need to first ask Server if you can change the array, if the change is in the scope (like dmg +99max) then it would work, but setting it to +9999 would be forbidden

[twin juniper]

but setting it to 98 would work?

[sinful tree]

No.......

[normal viper]

Well it's just a example how you can set it up

[sinful tree]

You wouldn't even do that.

The most you could do, is maybe say, I'd like to equip what is in slot 5.

picking up an item? oh that's a request to the server asking to pick up the actor you're looking at, or the server detects the overlap.

[twin juniper]

since clients doesnt need to know about the array of other clients, it only replicates for the owner in my case...

[sinful tree]

"Replications for the owner" means that it exists on the server and would replicate to whoever is marked as the owner.

It still exists on the owning client and the server.

[twin juniper]

So if I need a data from a client to another, I need to go through the server, if I dont it will be default... ?

[sinful tree]

You can only communicate to other clients VIA the server.

If you don't then nothing goes to those clients as you didn't go through the server.

[twin juniper]

some told me to loop through all clients and that would work

[sinful tree]

You could if you were running on the server, sure.

Clients cannot send any communications to other clients directly.

There is literrally no connection or means to do so within Unreal's networking system.

[twin juniper]

UPROPERTY(ReplicatedUsing = InventoryArrayWidgetClientUpdate, EditAnywhere)
TArray<FItem> ItemsArray;

InventoryArrayWidgetClientUpdate will run only on the owning client, right?

[sinful tree]

Do you have it set up with the COND_OwnerOnly replication condition?

Or does the thing containing this inventory exist on something that isn't replicated to everyone (like the player controller)?

[twin juniper]

yes ofc

we just did it

[sinful tree]

Then yes, it should only execute on the owning client.

[twin juniper]

good, I was just making sure it wasn't autoritive

[sinful tree]

OnReps in C++ don't fire on the server automatically unlike in blueprints

And the OnRep only triggers if a replication was received, and COND_OwnerOnly would prevent the replication from going to anyone else.

[twin juniper]

okkk

thx a lot @normal fulcrum @sinful tree ❤️

[patent zinc]

is the best way to prototype an online game to host the server in your own pc? i plannned on using aws but im kinda scared of it cus i have No Budget at All and i dont wanna accidentally go over the free tier limit for gamelift

[worthy portal]

by server do you mean actual game server where players connect and play or server that stores information about player progression etc?

[patent zinc]

since rn im trying to just get player interactions to work, the former

[worthy portal]

then i guess it'll be fine to host on your computer

[patent zinc]

ight ty, i assume aws would be better for player data when i get to working on it later on, right?

[worthy portal]

never really used aws, but i guess its fine for both game server and data stuff

[patent zinc]

understood

this is my first time doing somethin like this so im kinda Full of questions
and i KNOW its usually bad to start with an online game but i work on a "if the motivation is halted due to an issue the project dies Immediately" mindset

[worthy portal]

yeah, you should keep your game server(s) and data server separate from each other

[kindred widget]

This is exactly why it's bad to start with a multiplayer game though. There's going to be a lot of issues in the project on a singleplayer game. Multiplayer is just going to turn that into a nightmare.

That said. Unless you need something special. Start with listenservers where players can host games as well and stick with Steam. There is a lot more info out there to work with.

[patent zinc]

if it helps what im trying to do is like
instead there being "lobbies" you can pick from, whenever the player enters a zone/level/area (whatever you wanna call it), they get put in a "room" of sorts with a limit of 8 players
idk how to explain it better, but its the best description i could think of

,, i guess ? im not very knowdledged in this stuff

[worthy portal]

your explanation actually reminds me of minecraft minigames, where people enter portals and play some kind of game mode

isn't it similiar?

[patent zinc]

yeah that's pretty much it i think

[strong vapor]

is the Velocity variable in the CharacterMovementComponent client predicted?

[gloomy axle]

is this how I should handle item replication for players?

this is on a character that the player controller possess

I marked the InventoryItems array and other inventory related variables as replicated

do these need to be "run on server" instead of multicast

hmm

at the moment it's
client -> server

does it need to be client to server, server to multicast?

[tardy fossil]

yes

[gloomy axle]

hmm

[tardy fossil]

but if thats a widget blueprint it wont exist on the server

[gloomy axle]

nah it's on the character, controlled by a pc

Basically, I'd like for every player to know what each player has in their inventory

and for each player to be able to see each player's inventory functionlaity

functionality*

[tardy fossil]

i dont think a client can call a multicast function directlybut i might be wrong

[gloomy axle]

so for inventory related functions, if i want every player to look at every player's inventory functionalities (such as current slot selected, items in inventory, etc.) then I need to:
client -> event (execute on server) -> event (multicast)

since only server can multicast

this makes sense tbh

[tardy fossil]

also keep in mind these rpcs wont be run on players who join late, if thats an issue

[gloomy axle]

hgmm

so when the new player joins, I have to feed that player data

this might be an issue, maybe cause some lag

I'm essentially trying to create a lethal company prototype, if that helps

(the game isn't an exact copy of lethal company, but very similar lol)

hmm

I'll try client -> event (execute on server) -> event (multicast)

like players change materials on objects?

yes

it's not self-promo

I'll watch that if client -> event (execute on server) -> event (multicast) doesn't work

yeah dont worry this isn't, this is updated per player input

also

for some reason the player's rotation isn't replicated

like, the host can see other player rotations, but the client players cant see the host's rotation changes

ohh

well the character is

[sinful tree]

You don't want to multicast everything. Replicated variables are used to replicate stately things, like an inventory which is something that definitely has a state. You can multicast and it can appear to work, but that's not how the engine is designed. Multicast can be used for fire and forget events, like displaying a visual effect or playing a sound effect in response to something happening.

[gloomy axle]

let me check pc

[gloomy axle]

so should i multicast when player changes slot in their hotbar and a new item is there, show it

[sinful tree]

No

[gloomy axle]

I see

[sinful tree]

That's something stateful.

[gloomy axle]

so if the "CurrInventorySlotIndex" is replicated then itll be fine

like the int variable

[sinful tree]

Yes, and you'd set that variable as an "Rep w/ Notify" or "OnRep" which gives you a function that fires when a new value is received for that variable which you can then use to drive additional logic when that new value is received.

[gloomy axle]

what should the condition be?

none?

[sinful tree]

Depends on what you're wanting to do with the variable and who needs to receive it. For now, stick to None until you're more comfortable.

And none means there's no additional replication condition - it'll attempt to replicate to any clients who have the actor or component relevant.

[gloomy axle]

Oh okay, then none should be fine

[sinful tree]

Pawn rotation is usually replicated under a function "Get Base Aim Rotation" but the default projects don't have anything utilizing it to make the character look around so to speak.

[gloomy axle]

that makes sense

[sinful tree]

It is replicated, just not utilized by the anim BPs and such.

It's nothing with movement specifically, it's about where they're looking.... Like, if you open up the third person template and aim upwards to the sky, other players would still see you looking forward.

[gloomy axle]

huh, it seems like only the host actions are replicated for the clients. for these two functions

this is on the character blueprint, controlled by the player controller

for some reason it seems to add to the inventory, other players can see, but when dropped it doesn't work the second time

[sinful tree]

Again, you don't want to multicast everything. Something being held by the player is likely something stateful, meaning you'd have the server actually handle what happens on its end and replicate the results to others

[gloomy axle]

so only the On_Server part

[sinful tree]

Yes, otherwise you're basically having every client executing the code which isn't what you necessarily want.

[gloomy axle]

so it's looping the code per player, yea that makes sense

[sinful tree]

Yep, send to server, server handles what is supposed to happen, (ie modify replicated variables, or spawn/destroy replicated actors). You then use OnReps to trigger any additional logic if necessary based on the new values.

[gloomy axle]

changed it to this, the player host can pick up item and client players can see that, but client players can't pick up the items

[sinful tree]

What you have above looks replicated correctly now. What happens in these functions?

[gloomy axle]

so item interact checks to see if the player is holding an item, if it is then the player interacts with the held item first. if not then it does nothing

add to inventory does this

[sinful tree]

What is "Curr Hit Object"?

[gloomy axle]

curr hit object is set from a raycast, checked every tick

i know that's not the most optimal but yk

[sinful tree]

Ok so here's where it starts to get a bit off - you probably have that tick function firing on all instances of the game, and because this is a character, that means you're probably firing it for every character on every instance. It's not really necessary to do in that sense. You'd only need to maybe do it locally on the one client that is in control of that character rather than having all clients do these traces for all characters, right?

Like, you only really need to know what the locally controlled character is looking at, at any specific time.

[gloomy axle]

are you talking about just for the CurrHitObject? so that variable doesn't need to be replicated?

I see

[sinful tree]

Like it can make sense to do that on tick for a locally controlled character as you may want to know what they're looking at so you can show an interact prompt for example.

[gloomy axle]

makes sense because CurrHitObject is just what the player is lookingat

not what the player controls

[sinful tree]

So then that kind of needs to change what your code on the server does - as you'd prrobably still want the server to know what the player is looking at - and you have two options:

1. Let the client tell the server what they are looking at (Done by adding an "Actor" input on your Server RPC) and then passing in the local "Curr Hit Object"
2. Let the server run the same trace when attempting to perform that interaction, basically running the same logic for detection on the server.

Personally, I usually go with option 1 and then utilize the value passed in from the client.

[gloomy axle]

yeah I already changed it to option 1

huh, the client player still can't add the item to the inventory, but it's clearly looking at it

and I mean, I have a function that pops up with a "E" icon to tell the player to pick it up

that shows for the client

[sinful tree]

Next problem is here... These look like widget blueprint calls. Widgets don't replicate, so you can't use them to replicate any data or reference them across the network.

[gloomy axle]

ah okay

that's blocking the next step then

[sinful tree]

Your inventory should be something that is an object that replicates data, like a component or even just placed on the character.

[gloomy axle]

I've been meaning to research UI replication after fixing this

[sinful tree]

Your widgets then read from that object to represent what the data is saying about it.

[gloomy axle]

so this will be "false" no matter what

[sinful tree]

Yes, except for the host since they have a local widget themselves

[gloomy axle]

that makes sense

and the client cant have a local widget?

[sinful tree]

Sure but it won't exist on the server

Widgets are always only local

[gloomy axle]

yeah that's fine

at the moment it basically duplicates the ui

like when the client looks at a pickupable object, it shows the E icon on the host too

[sinful tree]

That's because of your tick 😉

The tick is running on all clients on all characters.

[twin juniper]

They could be on the server :3

but shouldn't 😄

[gloomy axle]

I see

[sinful tree]

And if your trace is detecting something on all of them and you have it adding a widget when any of them detect it, then they'd all see it.

[gloomy axle]

so I should only check for is local player

I forgot what the function or node is

[sinful tree]

is locally controlled

[twin juniper]

are we all doing inventory systems lol?

[gloomy axle]

yas

im trying to recreate lethal company's inventory system lol

almost there, just messes up for multiplayer

[sinful tree]

I wish... I'm currently in the process of designing a procedural galaxy generator

[twin juniper]

ohh that sounds cool

[gloomy axle]

this GetLookAtObject is on event tick

i added in that condition

[gloomy axle]

should I do the same for the inventory ui here?

[sinful tree]

No. Your UI needs to be driven by OnRep changes.

Right now it seems like your UI has the inventory data rather than having something replicated containing the inventory data.

[gloomy axle]

yeah I set a ref to the item

hmm

How would I do this OnRep?

[twin juniper]

I didnt even need to use IsLocallyControlled...

[sinful tree]

So you have a ref to the actor you want to pick up.
You can have a variable like "Slot1" which can contain an actor.

[gloomy axle]

yeah

[sinful tree]

So if you had that variable set to Rep W/ Notify, you'd then get an OnRep whenever the value of that variable changes.

That OnRep you can then have the UI update (if locally controlled!)

[narrow fog]

Gamers, I'm having a problem making sure an "expose on spawn" variable is replicated. I have units that record their current location as a reference to a CurrentTile actor BP. I have it set to Instance Editable and Replicated without a condition

In game, the CurrentTile is set on the server but not the client. Making a new boolean variable with the same settings works fine. Is there something I'm missing to properly replicate a reference to an actor?

[gloomy axle]

Oh the onrep event, gotcha

[sinful tree]

Just to make sure, is the actor itself replicated? (The reference one I mean, BP_Tile)
You may also want to use an OnRep to ensure that any startup logic that requires the reference actually can do it when the value is received.

[gloomy axle]

so OnRep_CurrHitObject, do the UI logic in this function?

[sinful tree]

Why are you OnRepping the current hit object?

Unless, that's what you're wanting to use as your "Slot".

[gloomy axle]

I need to set an item on interact

when the user presses E on it

I see

[amber vale]

Should programmers be using Unreal's push model these days, or is Epic still working on it?

[narrow fog]

The BP_Tile was not replicated, thanks for that, I figured it'd be something easy. This somehow broke the whole game board, but at least it correctly replicates the tile lmao

[sinful tree]

So really, the OnRep that needs to happen is with your Inventory Items Array. When that array changes, then that should be a signal as to when something entered or has left the inventory.

[gloomy axle]

Okay so I changed it to:

• CurrItemPickingUp, RepNotify actor set when a player presses E on the item they are looking at
• OnRepp_CurrItemPickingUp calls Add to Inventory

[sinful tree]

There is no need to OnRep what the client is looking at.

[gloomy axle]

no no

[sinful tree]

You don't want clients adding items to their inventory if their inventory is replicated as the server should be replicating it.

[gloomy axle]

it's only when the player presses E is it set to the currhitobject

CurrHitObject is not on rep

[sinful tree]

You don't need to onrep what they're picking up either.

[gloomy axle]

?

[sinful tree]

Same thing - you don't need the clients to do anything with adding to the inventory.

The server adds it to the inventory, that triggers an OnRep.

Client can update their UI based on what is now in their inventory.

[gloomy axle]

That sounds contradictory to something you said earlier, so now im confused

I don't use OnRep on the item I am adding to the inventory of a player?

[sinful tree]

OnReps are used to trigger logic, not to set replicated values on clients.

Client (I Want to Pick Up "Cash Register") > Server RPC (Actor: Cash Register) > Server Adds "Cash Register" actor to Inventory > OnRep Triggers > Client now knows "Cash Register" is in their inventory and can update their UI.

[gloomy axle]

So I just need to de-couple the inventory data and inventory ui

at the moment it's in one function

[sinful tree]

Yes, UI should only be used to represent data. The actual data should be stored on something that replicates that your UI can read from.

[sinful tree]

I see people talking about it fairly frequently.

[gleaming sequoia]

How should I get started making my game multiplayer?

I have, hopefully, followed decent code etiquette for like collisions damage events and whatnot. I just need a guide to spawn a second player and sync like the world. From videos on youtube, most of them are just saying to get some like eos integratiokn kit or some plugin but they say its recommended for those who dunno cpp at all. I do know c++, so what would you recommend I do?

[amber vale]

Not relevant but is this from Darker Nodes?

[gloomy axle]

nah it's Flat Nodes 🙂

works on 5.4.2

can't get node graph assistent to work tho 😦

[amber vale]

Is there a binary build for 5.4.2 or did you download it for 5.3 and migrate it to source?