multiplayer

[pallid mesa]

Been working recently around MoveAutomous

and I wanted to check how it all looked in ue5-main, got surprised to see a new CVAR that happened to fix the notify issue

a bit unconvenient that it is a CVAR 😦

but anyways... this is also set in Lyra's engine config

[quasi tide]

Maybe it was planned? Weird. I'd imagine it should be on by default and should be optional to be off.

[pallid mesa]

yeah

[open grove]

Helloo!
Currently using UE5, just loaded a new third person tenplate, attempted to use split screen using "Create Local Player" this doesn't seem to get any input from my second xbox controller. Both controllers work in the editor allowing me to move around. But it doesn't seem that a player controller for my second controller is being used/detected. Any help will be very appreciated 😄

[prisma snow]

Mmm any reason a server-executed multicast is only being fired on server (and not clients?)

I can ensure it is being called on the server

[quasi tide]

Clients aren't relevant

[prisma snow]

mmm this class is marked as always relevant

[worn wagon]

or it's a server only class like gamemode

[prisma snow]

it's basically RPCing some stuff to its client clones

mmm

The class itself is created on the server, but since it is marked as replicated, shouldn't it exist also on clients?

[twilit radish]

What are we talking about? Gamemode, player state, a custom actor?

[prisma snow]

A custom actor which acts as a helper so a subsystem can do networking stuff basically

This is part of some "old" code that I ported from 4.27 (a prototype I made) and it used to work there, so my bet is that something in the creation/spawning process is not correct and therefore is not existing on clients or smth

[worn wagon]

post code if you want more help

[prisma snow]

yeah I'll do, thanks

[strange apex]

Just a quick question, when i am hosting a lan server , it takes like 30 seconds to join as client 2, any way to speed that up ?

[dry pebble]

oh wow thank you! @thin stratus will this help you too?

[thin stratus]

Yes, thanks for the ping

[dry pebble]

@pallid mesa Also I read all your articles yesterday, they are amazing! Thank you for writing them. I have a question about your "A non-destructive and better synced network clock" - have you tested whether the slight difference in synced time between client and server would cause net corrections if gameplay mechanics were dependent on this time? E.g Reducing cooldown timers for GAS abilities by the RTT up to a certain ping?

[rocky topaz]

I have an issue with my vehicle replication, I'm working on a client authoritative mode but for some reason when I'm playing in a listen server it's state doesn't get replicated to clients (client to server and to other clients works)

[chrome bay]

Probably an oversight in the implementation

[rocky topaz]

    UFUNCTION()
    void OnRep_ReplicatedState();

    UPROPERTY(ReplicatedUsing=OnRep_ReplicatedState)
    FReplicatedState ReplicatedState;

    UFUNCTION(Server, Unreliable)
    void Server_ReplicateState(FReplicatedState NewReplicatedState);

void URacingTankMovementComp::OnRep_ReplicatedState()
{
    TankBody->SetWorldLocation(ReplicatedState.Location);
    TankBody->SetWorldRotation(ReplicatedState.Rotation);
    TankBody->SetPhysicsLinearVelocity(ReplicatedState.LinearVelocity);
    TankBody->SetPhysicsAngularVelocityInRadians(ReplicatedState.AngularVelocity);
}

void URacingTankMovementComp::Server_ReplicateState_Implementation(FReplicatedState NewReplicatedState)
{
    ReplicatedState = NewReplicatedState;
    OnRep_ReplicatedState();
}

OnTick :
    if (OwnerTank && OwnerTank->IsLocallyControlled())
    {
        ReplicatedState.Location = TankBody->GetComponentLocation();
        ReplicatedState.Rotation = TankBody->GetComponentRotation();
        ReplicatedState.AngularVelocity = TankBody->GetPhysicsAngularVelocityInRadians();
        ReplicatedState.LinearVelocity = TankBody->GetPhysicsLinearVelocity();

        if (!OwnerTank->HasAuthority())
        {
            Server_ReplicateState(ReplicatedState);    
        }

[rocky topaz]

this is what I'm doing

oh and

DOREPLIFETIME_CONDITION(URacingTankMovementComp, ReplicatedState, COND_SkipOwner);

[chrome bay]

        {```

[rocky topaz]

I'm using this

[chrome bay]

Listen server does have authority

[rocky topaz]

yeah but modifying the ReplicatedState struct should be enough to make it replicate no?

[chrome bay]

Oh NVM, you are setting it

[rocky topaz]

the Server_ReplicateState just sends it to set it yeah

[thin stratus]

You aren't calling OnRep then though

For the server at least

or?

[rocky topaz]

yeah that's also on purpose

[thin stratus]

Ok

[rocky topaz]

calling OnRep on server makes it reset the location and velocity every tick

[chrome bay]

I ma personally against calling OnReps for server as it makes actual replication harder to debug - but yeah presumably you need to apply it

Also, I assume you have disabled replicated movement on the owner?

[rocky topaz]

yup

[chrome bay]

Realistically, you shouldn't need any of this btw - you can just set the owning actors' replicated movement data (which contains physics state)

Which will also be cheaper - component replication/RPC's have additional overhead

Not usually anything to worry about, but becomes a factor at scale or when properties are updating a lot

[rocky topaz]

but that makes it server authoritative no?

[chrome bay]

Not necessarily, just ignore the updates on the receiving client

I.e. in OnRep_Movement guard against IsLocallyControlled or auto proxy or w/e

[rocky topaz]

I'm making a racing game and I want to let the player do whatever they want (cheating protection isn't required)

[rocky topaz]

oh?

[thin stratus]

All he's suggesting is to use the already replicating movement

And instead of applying it locally, you filter the call

[chrome bay]

In fact, Skeletal Meshes even have a flag that does that automatically for the purpose of vehicles

Exactly what it's meant for

Why it lives on USkeletalMeshComponent and not USceneComponent or w/e is anyone's guess though. 10/10 API decisions.

[rocky topaz]

how would I change the behaviour of movement replication though?

overriding OnRep_Movement?

[chrome bay]

If it's a physics simulating skeletal mesh, you don't even have to do that

Just uncheck "Replicate Physics To Autonomous Proxy" on the mesh

[rocky topaz]

damn

[chrome bay]

It's a stupid fortnite API thing that ended up in vanilla engine

Because apparently nobody would ever make a physics-simulating static mesh vehicle

Genius

[rocky topaz]

btw I'm in class (granted, it's a Shader Programming class) but teacher was like "you should use a multicast"

:thonk:

[chrome bay]

no

[thin stratus]

:D why does that sound like you need that to exist for StaticMeshes for your pet project

[chrome bay]

bad teacher

[chrome bay]

I don't luckily 😄

[rocky topaz]

I know I was like no as well but he got on my pc and started doing it

[quasi tide]

Interesting - do you just do what the OnRep would do, but by hand?

[chrome bay]

Just such a dumb decision to put it there IMO

[rocky topaz]

this is our best programming teacher btw

[chrome bay]

If server + client have to execute it, I make another func and have the OnRep call that

[chrome bay]

quit school tbh

[rocky topaz]

we have a "physics engine" and "network programming" teacher that never opened unreal

[chrome bay]

I kid

MP is hard, you need actual experience to teach it properly. No offence to the teachers.

[rocky topaz]

he was like "I'm sure Blueprints can be more performant than C++"

[rocky topaz]

no but like

he doesn't know shit it made me depressed

I went through all stages of grief on the first week of class with him

we had like 22hours of class where all he did was talk about politics and open youtube tutorials about how to make a blueprint

💀

[worn wagon]

what kind of politics

[quasi tide]

Interesting. Seems a long-winded way of doing:

Speed = 30;
if (GetNetMode() < NM_Client)
{
    OnRep_Speed();
}

It's the same at the end of the day, no? Or is there something that happened specifically that caused you to adopt your stance?

[rocky topaz]

french politics

he was like "it's going to get bloody very soon"

(I'm in france btw, despite my strong wish to not be here)

[chrome bay]

The problem for me is when I put a breakpoint in an OnRep function - I expect that breakpoint to only ever be hit on a client. It makes it harder to debug if the server is calling what is really client code

[rocky topaz]

he told us things would change radically in the next two weeks like a month and a half ago

and now this week he was like "it's gonna happen first weeks of january"

😂

[quasi tide]

Fair - I guess it depends on how you use OnReps. I design 'em where they're not only meant for client code personally.

[worn wagon]

motherfucker needs to focus on his work

[rocky topaz]

ikr, he's a politician actually

idk why they brought him here

school gave him like 100 hours of teaching

prolly 5000€

I would bet my ass he didn't teach jack shit to anyone

5000€ down the drain

[thin stratus]

Just tell him to rethink both of his careerpaths

[rocky topaz]

unless it's some kind of money laundering scheme 😬

[latent heart]

Complain, tell the school he has no idea what he's doing.

[kindred widget]

Just make sure to leave emotion out of it. Just lay out clean clear facts.

[worn wagon]

my not so well informed opinion is if you actually want to learn something properly and you don't need a degree or some kind of qualification for your career path, best to just find resources yourself than pay for college

[chrome bay]

@rocky topaz This has some extra "guff" from my implementation but hopefully it demonstrates the approach

Main point of note, is that when an RPC is received it's applied at the beginning of the frame. I had better/smoother results by applying client changes after the current physics tick - hence all the intermediatte data

[thin stratus]

"I learned more from some guy from the UK on Discord in 5 Minutes than from that guy in a school during the last 2 weeks."

[latent heart]

2 months*

[chrome bay]

Notice my incredible anti-cheat protection:
// TODO: Time / Cheat Verification

[kindred widget]

True opinion. The issue is that HR in most companies don't care how much you know. They're not wasting their time on your interview without some form of say so that you 'might' know what you're doing. College degrees aren't about learning, they're about getting your foot in the door.

[thin stratus]

best to just find resources yourself than pay for college
Small note: It's probably best to pay a tutor for that

[quasi tide]

Solid

[chrome bay]

EAC got nuttin on dis

[pallid mesa]

It depends on your logic and timing tolerances... ofc the synced clock will give you a closer view in both ends

[quasi tide]

I learned more from some guy from the UK on Discord in 5 Minute
To be fair - it is James and he is friggin' sweet 😅.

[rocky topaz]

he's the teacher for a ton of programming classes not just physics and networking

but yeah we did and he's getting fired next trimester afaik

[latent heart]

Get a refund.

[rocky topaz]

yeah definitely agreed, but I need a degree and I'm not paying this school

I was in an apprenticeship first year which paid for the school through a gov grant

[worn wagon]

You only need a degree if you're looking to join an existing company 😄

[rocky topaz]

I have a static mesh and I found it too

ah nvm I misunderstood what you said

[chrome bay]

OH WAIT

They moved it in 5.1

It's in PrimitiveComponent now

good guy Epic

[rocky topaz]

yeah as a broke man from a third world country (Africa)

[thin stratus]

Honestly, I got a Bachelor in Applied Science, Math and IT, and even though I did end up founding my own company, I wouldn't say this was wasted.

[rocky topaz]

I'm on 5.0.3 and I have it too

[worn wagon]

I'm just trying to justify my life choices 😭

[rocky topaz]

it's hard to start a company

[chrome bay]

Yeah must have been recent, I recall it only being in skeletal mesh for no reason whatsoever

[thin stratus]

sad beep

[rocky topaz]

well this is weird

I removed all my replication stuff

and my server's state is still not replicating to the clients

    SetReplicateMovement(true);
    
    Mesh = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("Mesh"));
    SetRootComponent(Mesh);
    Mesh->SetSimulatePhysics(true);
    Mesh->bReplicatePhysicsToAutonomousProxy = false;

[prisma snow]

Ok, so after debugging a bit I am still clueless so, here's my code:

In my subsystem, the helper replicated actor is created:

// MySubsystem.h
UPROPERTY()
AReplicationHelper* MyHelper;

// MySubsystem.cpp
void UMySubsystem::Initialize(FSubsystemCollectionBase& Collection)
{
    if (GEngine->GetNetMode(GetWorld()) != NM_Client)
    {
        MyHelper = GetWorld()->SpawnActor<AReplicationHelper>(AReplicationHelper::StaticClass());
    }
}

Then, in AReplicationHelper constructor I set bReplicates and bAlwaysRelevant to true.

The function that is multicasted from the server:

// .h
UFUNCTION(NetMulticast, Unreliable)
void NetCastLocations(const TArray<FUnitLocationNetUpdate>& UnitLocations, int32 ServerStepNumber);

void AReplicationHelper::NetCastLocations_Implementation(const TArray<FUnitLocationNetUpdate>& UnitLocations,
                                                                 int32 ServerStepNumber)
{
        // only server reaches this code
    if (GetNetMode() != NM_Client)
    {
        return;
    }

    // do my client-side logic
}

[chrome bay]

@prisma snow I think I know. U ready for dis?

[prisma snow]

yes

[chrome bay]

It's unsafe to access ENetMode in A world subsystems initialize

I had to jump through repeated hoops for this

[prisma snow]

MMM

[quasi tide]

Wait - it is? I think I might be doing that 😅

[prisma snow]

I can ensure that the actor exists in both client and server

but that's it

[chrome bay]

Some really obscure UWorld lifetimes in PIE make it a PITA

[rocky topaz]

this is soo weird

[chrome bay]

So it's possible that both server + client are spawning their own

[rocky topaz]

why would the server's state not replicate to clients

[prisma snow]

that would make prefect sense

[chrome bay]

You can get around it, 1 sec

[prisma snow]

Jambax for president

xD

[quasi tide]

This is how I'm doing my server only subsystem 😅

if (!Super::ShouldCreateSubsystem(Outer))
{
    return false;
}

UWorld* World = Cast<UWorld>(Outer);
return World->GetNetMode() < NM_Client;

[chrome bay]

This is the dumb code I had to use:

{
    const UWorld* lWorld = OverrideWorld ? OverrideWorld : GetWorld();
    check(lWorld);

    OutMode = lWorld->GetNetMode();

#if WITH_EDITOR
    // PIE creates some obscure UWorld lifetimes that makes NetMode access more difficult.
    // See https://udn.unrealengine.com/s/question/0D54z00007DW1CQCA1/why-are-uworldsubsystems-initialized-before-uworld-is-initialized
    if (lWorld->IsPlayInEditor())
    {
        UEditorEngine* const EditorEngine = CastChecked<UEditorEngine>(GEngine);
        const UPackage* Package = Cast<UPackage>(lWorld->GetOuter());
        if (!Package || Package->GetPIEInstanceID() == INDEX_NONE)
        {
            // This is a Transient UPackage used for PIE Client worlds.
            OutMode = ENetMode::NM_MAX;
            return false;
        }
        else
        {
            // We can get the UGameInstance/UNetDriver from here, *before* the UWorld properties are set
            const FWorldContext* PIEWC = EditorEngine->GetWorldContextFromPIEInstance(Package->GetPIEInstanceID());
            if (ensureAlways(PIEWC))
            {
                if (!PIEWC->PendingNetGame)
                {
                    OutMode = PIEWC->RunAsDedicated ? ENetMode::NM_DedicatedServer : ENetMode::NM_Standalone;
                }
                else if (ensureAlways(PIEWC->PendingNetGame->NetDriver))
                {
                    OutMode = PIEWC->PendingNetGame->NetDriver->GetNetMode();
                }
            }
        }
    }
#endif

    return true;
}```

Also then - I recommend moving the actor spawn to some post-world-initialized function

The problem is that subsystems are initialized before the world is actually initialied, but the order varies between editor vs packaged

{
    Super::Initialize(Collection);

    const UWorld* lWorld = GetWorld();
    check(lWorld && lWorld->IsGameWorld() && lWorld->PersistentLevel != nullptr);

    /* Can't actually do proper initialization until much later... */
    PostInitWorldDelegateHandle = FCoreUObjectDelegates::PostLoadMapWithWorld.AddUObject(this, &UHT_WorldManager::PostInitWorldInternal);

#if WITH_EDITOR
    /* Editor environment is even more fucking annoying */
    PostInitWorldPIEDelegateHandle = FEditorDelegates::PostPIEStarted.AddUObject(this, &UHT_WorldManager::PostInitWorldPIEInternal);
#endif
}

void UHT_WorldManager::Deinitialize()
{
    ManagerTickFunction.UnRegisterTickFunction();
    FCoreUObjectDelegates::PostLoadMapWithWorld.Remove(PostInitWorldDelegateHandle);
#if WITH_EDITOR
    FEditorDelegates::PostPIEStarted.Remove(PostInitWorldPIEDelegateHandle);
#endif

    Super::Deinitialize();
}

void UHT_WorldManager::PostInitWorldInternal(UWorld* NewWorld)
{
    const UWorld* lWorld = GetWorld();
    if (lWorld && lWorld == NewWorld && !bHasPostWorldInitialized)
    {
        bHasPostWorldInitialized = true;

        FCoreUObjectDelegates::PostLoadMapWithWorld.Remove(PostInitWorldDelegateHandle);
#if WITH_EDITOR
        FEditorDelegates::PostPIEStarted.Remove(PostInitWorldPIEDelegateHandle);
#endif

        // Handle Tick Registration now.
        if (!ManagerTickFunction.IsTickFunctionRegistered() && ManagerTickFunction.bCanEverTick)
        {
            ManagerTickFunction.Target = this;
            ManagerTickFunction.SetTickFunctionEnable(ManagerTickFunction.bStartWithTickEnabled || ManagerTickFunction.IsTickFunctionEnabled());
            ManagerTickFunction.RegisterTickFunction(lWorld->PersistentLevel);
        }

        OnWorldInitialized();
    }
}

#if WITH_EDITOR
void UHT_WorldManager::PostInitWorldPIEInternal(bool bSimulating)
{
    PostInitWorldInternal(GetWorld());
}
#endif```

What fun.

Sorry for wall of text

[prisma snow]

I see, so basically I should use that special function + initialize a bit later

what a mess Epic games xD

[chrome bay]

yeah, that fixed it for me at least

I had the same problem essentially

[quasi tide]

@hollow eagle Tagging you about this reply because I am using some code that you suggested 😅. Figured you might be interested.

[chrome bay]

I wanted to onbly have certain subsystems initialized on server for e.g.

[rocky topaz]

lemme put my messages back together

[chrome bay]

So had to do this shiz

{
    if (Super::ShouldCreateSubsystem(InOuter))
    {
        const UWorld* lWorld = Cast<UWorld>(InOuter);
        if (lWorld && lWorld->IsGameWorld())
        {
#if WITH_EDITOR
            // PIE creates temporary worlds for Net Clients which should never initialize subsystems.
            if (lWorld->IsPlayInEditor())
            {
                const UPackage* OuterPackage = CastChecked<UPackage>(lWorld->GetOuter());
                if (!OuterPackage || OuterPackage->GetPIEInstanceID() == INDEX_NONE)
                {
                    return false;
                }
            }
#endif
            if (CheckNetMode(lWorld) && CheckLevelName(lWorld))
            {
                return true;
            }
        }
    }

    return false;
}```

[prisma snow]

lol

[rocky topaz]

so I just set replicates movement and unchecked autonomous proxy replication but it's not working as it was with my implementation
(it wasn't replicating earlier because the blueprint kept replicating movement unchecked 🤦🏻‍♂️ )
the movement isn't going from autonomous proxy to the authority like, I flipped a car in the server and it started moving upside down when I was moving in autonomous proxy

[chrome bay]

Maybe i should just dump the whole class on git

[prisma snow]

maybe we should set on fire the person(s) that did this to subsystems

[chrome bay]

tbh I think this is mostly PIE shennanigans and the hax it creates

The way the world is duplicated by editor GI is wierd

[pallid mesa]

thanks; the blog needs some love... there are loads of info being lost in discord, god bless the chat history... but discord in a way... killed the forums and dev-blogposts

[rocky topaz]

@chrome bay did you read my messages? 🥺

[dry pebble]

Ah thank you. Are you saying there a way to have a timing tolerance before a net correction? Kind of like the distance tolerance threshold in GetPredictionData_Client()? Or am I way off?

        MutableThis->ClientPredictionData->MaxSmoothNetUpdateDist = 92.f;
        MutableThis->ClientPredictionData->NoSmoothNetUpdateDist = 140.f;```

[quasi tide]

/* Editor environment is even more fucking annoying */
😅

[dry pebble]

So true, we need Chat GPT to index the discord into blog posts lol

[pallid mesa]

Not exactly, it is implementation dependent... but in this case a synced clock can help you with rewindings

So for example... I've shot my weapon at this angle at 10.33

The server will receive this information, and since clocks are synced, it will be able to rewind the victim's capsule to that point in time

meaning that you can trust that your 10.33 are equivalent to the 10.33 in the server

[rocky topaz]

welp I have no clue what's wrong with the default move replication and I don't have time to dive into it I guess I'll just go back to my old issue

when a struct field that's marked as replicated is modified on the server it's replicated to all clients right?

[pallid mesa]

you need to replicate the whole struct

[rocky topaz]

yeah the whole struct is

can you take a look at what I'm doing please? @pallid mesa

[pallid mesa]

and mark the fileds u don't wish to replicate as NotReplicated

[rocky topaz]

so this is my struct ```h
USTRUCT()
struct FReplicatedState
{
GENERATED_BODY()

UPROPERTY()
FVector Location;

UPROPERTY()
FRotator Rotation;

UPROPERTY()
FVector LinearVelocity;

UPROPERTY()
FVector AngularVelocity;

};

I have this in my header : ```h
UFUNCTION()
void OnRep_ReplicatedState();

UPROPERTY(ReplicatedUsing=OnRep_ReplicatedState)
FReplicatedState ReplicatedState;

UFUNCTION(Server, Unreliable)
void Server_ReplicateState(FReplicatedState NewReplicatedState);

void URacingTankMovementComp::OnRep_ReplicatedState()
{
    TankBody->SetWorldLocation(ReplicatedState.Location);
    TankBody->SetWorldRotation(ReplicatedState.Rotation);
    TankBody->SetPhysicsLinearVelocity(ReplicatedState.LinearVelocity);
    TankBody->SetPhysicsAngularVelocityInRadians(ReplicatedState.AngularVelocity);
}

void URacingTankMovementComp::Server_ReplicateState_Implementation(FReplicatedState NewReplicatedState)
{
    ReplicatedState = NewReplicatedState;
    OnRep_ReplicatedState();
}


void OnTick...
    if (OwnerTank && OwnerTank->IsLocallyControlled())
    {
        ReplicatedState.Location = TankBody->GetComponentLocation();
        ReplicatedState.Rotation = TankBody->GetComponentRotation();
        ReplicatedState.AngularVelocity = TankBody->GetPhysicsAngularVelocityInRadians();
        ReplicatedState.LinearVelocity = TankBody->GetPhysicsLinearVelocity();

        if (!OwnerTank->HasAuthority())
        {
            Server_ReplicateState(ReplicatedState);    
        }
    }```

and this is the body

my issue is that the Server's state isn't being replicated to clients

[dry pebble]

Ahh yess for server side rewinding. I've implemented that before from stephen's course, it's very handy and syncing time is a great use case for that (and a day night cycle across servers). I was curious more about client side prediction cooldown timers for GAS abilities. The idea Eki was talking about where you minus the RTT from the server's cooldown. Some people said it wouldn't work because you can't get frame perfect time sync between client and server. Where you get a result that's accurate +/- 5 ms, but that difference is the difference of a few frames. And just being off by one frame can cause a net correction. Curious if you have insight on that?

[rocky topaz]

I really don't get it as there should be no reason the ReplicatedState of the pawn of my ListenServer wouldn't get replicated to clients

[pallid mesa]

ur phys state only replicates to sim proxies?

[rocky topaz]

it's getting modified in the server itself so it should call the RepNotify

[rocky topaz]

yup

[pallid mesa]

it should be set that way in getfetimereplicatedprops

can i see¿ 👀

[rocky topaz]

I'm using DOREPLIFETIME_CONDITION(URacingTankMovementComp, ReplicatedState, COND_SkipOwner);

should it be COND_SimulatedOnly?

other clients aren't the owners of the server's pawn so it shouldn't be skipped with this either

🥹

[pallid mesa]

I honestly haven't tried, but I guess your RTT compute would be more precise with this method therefore you might be able to avoid a rollback

[rocky topaz]

I'm so puzzled

nevermind it works now by some kind of magic

wth

FReplicatedState NewReplicatedState;
        
        NewReplicatedState.Location = TankBody->GetComponentLocation();
        NewReplicatedState.Rotation = TankBody->GetComponentRotation();
        NewReplicatedState.AngularVelocity = TankBody->GetPhysicsAngularVelocityInRadians();
        NewReplicatedState.LinearVelocity = TankBody->GetPhysicsLinearVelocity();

        if (!OwnerTank->HasAuthority())
        {
            Server_ReplicateState(NewReplicatedState);    
        }
        else
        {
            ReplicatedState = NewReplicatedState;
        }```

I changed the tick to this

shouldn't modifying the existing struct in the server trigger a replication too?

[pallid mesa]

yes

I wasn't honestly seeing what was happening

oversight?

[rocky topaz]

so weird

[pallid mesa]

although the initial code was a bit confusing, i like it better now

[rocky topaz]

it's probably an issue coming from how a struct's dirty state is detected

[pallid mesa]

I was thinking that maybe your onrep wasn't getting called because the values where equivalent due to the predictive setting

but you unpiezed me after saying you were skipping the owner

[rocky topaz]

wait nevermind ReplicatesMovement was set

it might still not be solved

I had commented it in code but I forgot it's set to true by default

nevermind the issue is still here

https://media.discordapp.net/attachments/603649974042886296/804409299517571092/image0-19.gif

I sooo don't get it now

[rocky topaz]

what predictive setting?

[prisma snow]

@chrome bay I need to include UnrealEd in the module dependencies (public or private) to use your wonderful hack right?

[pallid mesa]

onreps on C++ only get called when the value differs

[rocky topaz]

oh yeah

well now we can be sure the value differs no?

the only solution I'm thinking of is a multicast gasps

but I really don't want to use a multicast

[prisma snow]

For some reason adding it to the dependencies breaks my compile xD

[glacial pollen]

Sometimes unreal really does not make sense.

[rocky topaz]

@pallid mesa do you give up?

welp I guess this means yes

wtf

turning the struct into a blueprint type fixed it?

or recompiling yet again

I have no clue

[pallid mesa]

I'm doing many things parallely and trying to assemble a chair x'D not the best time now @rocky topaz

[rocky topaz]

well it got fixed for some reason

[chrome bay]

Dun it
https://github.com/TheJamsh/UnrealSnippets/tree/main/Code/World Subsystem

[turbid sable]

Could anyone confirm this?

From reading the docs, ownership of an actor is not really the same as the actor's netrole. If you, the player, controls a pawn, you'll have ownership of the pawn, but the netrole could still be authorative on the server, and proxy for your local client.

If the above is true, would anyone know the reason why calling a client RPC on a pawn controlled by a local player from the server fail? Testing in PIE as a local client, and I get no logs that should appear

[chrome bay]

Ownership essentially means "who is allowed to call Server RPC's on this actor", and is the "NetOwner"

A client can "own" an actor, but if it's a replicated actor created by the server, they do not have authority over it.

Authority != Ownership

Owner also dictates which connection will receive the client RPC, if any

Possessed pawns are by default also "owned" by the controller, so clients RPC's should arrive and execute

[graceful flame]

So if you were to place a blueprint actor in the world and within that blueprint actor there's some sort of overlap event. Does that overlap run on server? client? both?

[chrome bay]

both

[graceful flame]

Okay so if that overlap needs to affect your character, would it make more sense to add on to the character's capsule overlap event and check for that actor instead?

or I guess that's when it starts to become "it depends" as the answer because other aspects of the game will influence how it should be designed?

[turbid sable]

Went on a deep dive with the debugger and the reason why I'm not getting my client RPC seems to be due the following inside the NetDriver

    const FFieldNetCache* FieldCache = ClassCache->GetFromField(Function);
    if (!FieldCache)
    {
        DEBUG_REMOTEFUNCTION(TEXT("FieldCache empty, not calling %s::%s"), *GetNameSafe(Actor), *GetNameSafe(Function));
        return;
    }

Field cache is null, anyone know what could possibly be the reason for this?

[weak linden]

It may execute on both, but you can still enclose any functionality in a HasAuthority check to ensure that you only do X, Y or Z on the server, call a function in the overlapping character, run an RPC, etc, etc

[quasi tide]

For trigger boxes, I only spawn them on the server.

[graceful flame]

Yea I'm already using HasAuthority checks all throughout my project. I'm mostly curious about which overlap event to use. The player controlled character's capsule OnBeginOverlap or the level placed blueprint actor's box collider OnBeginOverlap if the end goal is to change something about the character.

But I'm liking the idea of @quasi tide to only spawn the box collider server side. You can save resources client side but not having anything to check and still have server side checking.

[quasi tide]

Sounds more like a design question.

I'd have the box collider change it personally. With the character exposing a method that allows something from the outside to change its state.

[weak linden]

I'd have the box collider change it personally. With the character exposing a method that allows something from the outside to change its state.

This is the way I'd go about it too IMO

[graceful flame]

Yea okay, makes sense. I'm at a point in my game where I've learned a lot and made a lot, but now its time to go back and refactor some of my older work to be more optimized.

[weak linden]

🙏 I do love me a good refactor of "junk I made a year ago" session

[graceful flame]

Since the level placed actor doesn't move the OnBeginOverlap event only runs when a character or something else that can move triggers it, whereas the character's capsule is pretty much always overlapping as they move around the level. So yes it makes way more sense to have the gameplay logic to reside on the static level placed actor then have it send an interface message to ANY actor that overlaps it. Then on the character an interface event is implemented with a HasAuthority check then whatever needs to happen can happen.

[prisma snow]

much appreciated. Indeed that was the problem

[weak linden]

If you do the authority check in the character, you have the potential for the event to be fired twice, if you're not only spawning the box collider on the server anyway, this could lead to unintended side effects (client code running before the server, or the other way around), if something needs to happen client side, do it via an RPC as a result of the servers decisions from the server

[quasi tide]

Don't need the has auth check if you only have the trigger on the server or if you do the has auth check in the tirgger

[weak linden]

Yes, exactly, simple change, big side effects, if not thought through

[sonic python]

Hey Does Anyone know

How to make in app currency?

If you know can you give me some.links abt tutorials..

[quasi tide]

int MyMoney = 1000;

[sonic python]

For in app purchase

[weak linden]

As in, real money?

[sonic python]

Yes

[weak linden]

That's a topic much larger than the scope of a discord message/basic tutorial

[graceful flame]

Who's your payment processor?

[sonic python]

Whaaat?

[quasi tide]

1. Make in-game currency, like you would for an RPG or any game that involves money in games.
2. Now, make a backend (or use a 3rd party service) that updates the client's account's money after they make a purchase.
3. Update on the client their account money

[sonic python]

Playstore?

[sonic python]

Epic games ?

[graceful flame]

No i mean the payment processor, like who accepts and processes the credit cards if its real money.

[quasi tide]

Maybe. Idk - I haven't looked.

[sonic python]

Client - Myself?

[graceful flame]

Ummm

[weak linden]

Where are you publishing your game?

[graceful flame]

I don't think you have partnerships with the major credit card providers so...

[weak linden]

Steam, Playstore, Epic Store, etc?

[quasi tide]

The concept is really just adding an API call to some server that will update your in-game currency.

[latent heart]

I would have thought the playstore or whatever mac uses has some sort of api for taking your money.

[graceful flame]

Isn't that were you just buy the app?

[sonic python]

Playstore

[weak linden]

PlayStore probably has an in-app purchase API

[sonic python]

Yes

[weak linden]

You will need to look into it yourself, but that's the place to start

[sonic python]

Like I have a game currency set up.

Hmm It's my first time doing it

[graceful flame]

If you just want "Gold" for your game then its like this stuff #multiplayer message

[sonic python]

Can you explain more

[weak linden]

https://docs.unrealengine.com/5.1/en-US/how-to-use-in-app-purchases-in-unreal-engine-projects-on-android/

Epic has a guide on this

[sonic python]

Yeah Done a small game with no money making thing

Okay

Now How Should I set up the value of my game currency to the real money?

[quasi tide]

100% completely up to you

[sonic python]

Oh nicee

Now where should I set it up?

The Value of my game currency

[latent heart]

In your mind.

FML

[sonic python]

Damn

Okay

[latent heart]

#define REAL_MONEY_TO_GAME_MONEY 50

[sonic python]

If I'm having like a dollar equal to a 1 unit of my game currency

[prisma snow]

How could I go about debugging the correspondence of two actors in a client/server?

I have a situation where the units in my formation are assigned to different spots in the client and the server, and seeing how it is happening would help a lot to figure out (and test) how to fix it

[sonic python]

Oh

[quasi tide]

#cpp message

[latent heart]

UE_LOG?

[prisma snow]

Potentially, I'll need a way to order those units in a deterministic way using an ID or similar that is common to server/client

[sonic python]

Okay

[latent heart]

Revenge by proxy, huh?! 😛

[sonic python]

Then like for playstore

[prisma snow]

With the UE_LOG I cannot "see" the units names or IDs or whatever on screen. Since I am debugging positions, a visual helper would be more useful in the long run than a console log.

[latent heart]

You can see them on screen if you look at the output log! /troll

Just draw a debug dot at the point on the server (assume listen) and the client

[prisma snow]

hahaha touche. But seriously, I think thr best would be to see it in top of the units

[sonic python]

Like $10 = 1 Game currency

[prisma snow]

I have lots of debug shapes for the boid simulation, it's the text one that seems bugged (doesn't change position with the movement updates unlike the other ones)

[sonic python]

They Should Buy X game currency for some amount right?

Then Where Should I set the real amount , for playstore?

[weak linden]

DrawDebugText (can't remember the BP counterpart, probably the same) will move with the actor/objects if you have the actor reference set, I use it to debug my games vehicle positions

[sonic python]

I did

Like How ?

[graceful flame]

Just to rewind the convo a little bit, if you were to have something like a damage zone actor which can damage the player when they overlap it. Does that mean I should have two separate actors. One which contains the timelines for visuals and audio and another actor which contains only the box collider for overlap events to drive gameplay logic. The box collider actor would have Net Load On Client set to false?

I've been adding box collider components to level placed blueprint actors, but I guess those are running both client and server side even though I only need to check data during the overlap on the server.

[sonic python]

How ?

[prisma snow]

nice will try that, without the actor reference it was not working. Since the rest of debug shapes do not require an actor, I expected the same here

[weak linden]

You can use the same actor, just ensure that only the trigger box itself is created on the server (or do if !HasAuthority ->DestroyComponent)

[sonic python]

Now I Have Finished a big game u know , did everything, setted up in game currency

After that what's the next step for in app money

[graceful flame]

This part with blueprints?

Components don't have Net Load On Client option like entire actors do.

[sonic python]

Confused

[graceful flame]

I suppose somethings could change on EventBeginPlay

[weak linden]

It's the same in BP as C++, BP is SwitchHasAuthority and DestroyComponent also exists

[graceful flame]

Yea I was hoping for some editor level checkbox for the component I want to skip loading on the client

[weak linden]

Yes, just destroy the trigger client side on begin play, or only spawn it (Add XXX Component) on the server

[graceful flame]

But I can settle for EventBeginPlay changes yeah

okay cool, thanks @weak linden

[weak linden]

Tech Jesus 🙏

[sonic python]

Okay not confused

But still

Oh okay I kinda understood

[quasi tide]

Even better - you can only add the component if it is client using one of those fancy macros in C++ land.

I want to say it is something like UE_CLIENT but idk. Would have to search. Maybe UE_SERVER or something like that.

[graceful flame]

Yea I'm going to start migrating the heavy stuff first into c++ soon

[quasi tide]

Look at the character class on how they are adding the arrow component. Just do that, but with w/e the server/client macro is

[sonic python]

Now this is for the players buying - the clients , the customers

[pallid mesa]

Hey Jambax, do you plan to add more snippets to this repo? Maybe it could be nice to pin it 😄

[chrome bay]

Yeah probably will now I've actually made it :d

Honestly just lack of any kind of familiarity with Git

Gists look quite cool tbh

Easy to copy-pasta straight in. Do they end up in a repro somewhere where you can modify them etc or is it just pastebin but better?

oooh

[pallid mesa]

I prefer the repo tbh 😄 samples can be indexed in a master-readme easier (less hassle)

rather than a list of gists

It's a good initiative 👍 Thanks James

[weak linden]

I also believe (maybe incorrect), there isn't a way to see another users gists without the link? A repo is just right there

Oh, it's a separate sub domain

That's significantly less convenient than just having a "Gists" button like they do for repositories on a user profile

[pallid mesa]

are gist just single-files

or can they be a combo of files?

muuh uh i don't like it :(

[weak linden]

That works, but still a minor inconvenience

[distant vault]

hello, i'm having some problems with show a widgets to the player that collides with an object and has a specific role attack to it(multiplayer). The problem is when the player collides with it, the widget get show on the other clients screen that has the role.

[sinful tree]

Collisions can happen on all clients. If this collider is only checking for players, and you only want your widget to show to the player doing the overlapping, cast "Other Actor" to your character, and then check if it is locally controlled. If true, then show the widget.

[distant vault]

thanks was able to get it working (as you said, the event was called for all clients and server)

[versed ocean]

Having some issues because obviously I'm misunderstanding something, but I made a dedicated server, I have 2 clients and a server, I made an object called a Bookshelf that is just out in the world, and it holds however many books the math calculates out it can, I was generating them on BeginPlay() procedurally and putting them on the shelf. I'm having a hard time understanding where the logic goes now I'm in multiplayer land. I had it all mastered on the client. My current goal is to have the bookshelf contain the same exact books on all clients. I tried to make the CreateBook() a UFUCTION(Server, Reliable) moved function logic to CreateBook_Implementation. Then I set the Book object to replicate. But no one owns the bookshelf its just out in the world so that method doesnt work, because the server version ticking doesnt have an owner? I'm strugglign with this. So I changed it to a UFUCTION(Multicast) just experimenting, and it does now start spawning the books on the client, but of course the order is different, etc because it appears to be taking place on the client, called from the Server ( which as I understand it is exactly what multicast does ) so I feel like I want a UFUCTION(Server) but honestly I have no idea at this point. Willing to show all the code, etc..

[weak linden]

You might want to do something like this instead of using an RPC.

void AMyBookShelf::BeginPlay()
{
    Super::BeginPlay();
    
    if (HasAuthority())
    {
        // Generate books here.
    }
}

This way, only the server will generate the books

Lastly, just as a note, always try and prefix your RPCs where they should be executed, I.E a Server RPC will be called ServerMySomething, likewise a client RPC will be ClientMySomething and a Multicast would be MulticastMySomething helps with readability

[versed ocean]

Always appreciated.

[weak linden]

👌 Happy to help

One thing I'd like to say, if these books aren't gameplay relevant, I'd personally just have them local to each client, most players won't be too fussed if the top shelf doesn't have a large book 3rd from the right for them but their friend does 😛

If it's a must, but they don't do anything special, you can just drop down the Net Update Frequency to a very small number so they're not hogging your bandwidth

[versed ocean]

Part of my problem may have been I was trying what you suggest as well, but in the tick -- does the server not Tick objects?

i just moved it to begin play with 1 book to test as you mentioned.

[weak linden]

The server will tick objects as long as you've got it enabled on the server

(By default it will tick everywhere anyway so it's not something you manually need to do)

[versed ocean]

alright alright .. hmm still digging -- was shared a PDF on networking in cpp channel will read and experiment a bit here

[weak linden]

You'll get there eventually 😄

My suggestion, if you wanted these books to be "visually" correct on each client, but they serve no purpose other than decoration, you *could* have the server generate an array of books with their indexes matching the shelf, then just send that information over to clients (via an OnRep) to create locally so the books won't need to be replicated at all (which will save more bandwidth over however many shelves you intend on having)

[versed ocean]

Alright I think I understand the route you're mentioning there... I did that OnRep to sync my healthbars I will give that a try, wasnt sure you could do that with complex types *custom classes

[pastel fiber]

Is it possible to make completely TakeDamage() execute only on the server?
As you can see, the following implementation is not efficient because these two lines are still executed on the clients.

float NewCurrentHealth = CurrentHealth - DamageTaken;
return NewCurrentHealth;

Here is the complete code:

void AMyCharacter::SetCurrentHealth(float HealthValue)
{
    if (GetLocalRole() == ROLE_Authority)
    {
        CurrentHealth = FMath::Clamp(HealthValue, 0.f, MaxHealth);
        OnHealthUpdate();
    }
}

float AMyCharacter::TakeDamage(float DamageTaken, FDamageEvent const& DamageEvent, AController* EventInstigator, AActor* DamageCauser)
{
    float NewCurrentHealth = CurrentHealth - DamageTaken;
    SetCurrentHealth(NewCurrentHealth);

    return NewCurrentHealth;
}

[weak linden]

You can OnRep almost anything you like, what I'd likely do for a solution for racks that have a different number of shelves is something like this.

enum EBookSize;
struct FBookShelf
{
    // Indexes for book order (0 is far left of the shelf, etc).
    TArray<EBookSize> BooksForThisShelf;
}

// Bookshelf actor class.
// Index corresponds to what shelf books belong on, 0 for bottom, 1 top, etc, etc.
UPROP(ReplicatedUsing = OnRep_Shelves)
TArray<FBookShelf> Shelves;

[weak linden]

How're you applying the damage?

[pastel fiber]

// Called when the game starts or when spawned
void AMyProjectile::BeginPlay()
{
    Super::BeginPlay();

    if (GetLocalRole() == ROLE_Authority)
    {
        SphereComponent->OnComponentHit.AddDynamic(this, &ThisClass::OnProjectileImpact);
    }
}

void AMyProjectile::Destroyed()
{
    FVector SpawnLocation = GetActorLocation();
    UGameplayStatics::SpawnEmitterAtLocation(
        this,
        ExplosionEffect,
        SpawnLocation,
        FRotator::ZeroRotator,
        true,
        EPSCPoolMethod::AutoRelease);
}

void AMyProjectile::OnProjectileImpact(
    UPrimitiveComponent* HitComponent,
    AActor* OtherActor,
    UPrimitiveComponent* OtherComp,
    FVector NormalImpulse,
    const FHitResult& Hit)
{
    if (OtherActor)
    {
        UGameplayStatics::ApplyPointDamage(
            OtherActor, 
            Damage, 
            NormalImpulse, 
            Hit, 
            GetInstigator()->Controller, 
            this, 
            DamageType);
    }

    Destroy();
}

[weak linden]

Huh, so ApplyDamage is calling TakeDamage client side too?

[versed ocean]

I was over complicating the living shit out of it.... smh.... bReplicates on the Actor ( my book and my bookshelf ) then like you said in the BeginPlay, make the books if there is authoirty ( ie: on the server )

done deal, works. thanks lol

Really appreciate the help @weak linden

[weak linden]

Nicely done! 😄 You're welcome

[pastel fiber]

Oh my ghost. TakeDamage() is executed only on the server. @weak linden 🙂

[dim trail]

does fps affect server cost?

[pastel fiber]

I don't think so. FPS is related on clients that simulate the shared world.

[weak linden]

If you mean client side FPS, then no, server and client framerate are independent

That being said, the server does also have a framerate, so if you have a weaker performing machine, you will have a lower server-side framerate (which would mean you'd need a more expensive one)

[hushed rain]

When I possess something new(a drone), the character(soldier) left behind is always "owned" by the server, and when I shoot it with the server it's like I shoot myself. How would I fix this?

[weak linden]

You might be able to set the instigator to null on the old character when you de-possess it

[hexed pewter]

I'm in APlayerState and I wanted to let know my UI that something has changed.
Is it okay to broadcast a delegate from OnRep_SomeProperty() so my UI can update whenever playerstate changes or are there some better alternatives?

[weak linden]

That's perfectly fine to do, just be sure to check !UE_SERVER to ensure it happens only on the client

void APlayerState::OnRep_SomeProperty()
{
#if !UE_SERVER
    // Do your UI update here.
#endif
}

[thin stratus]

Keep in mind OnRep doesn't call on servers anyway if done via c++

[weak linden]

If you don't explicitly call it at least

With that in mind actually, I've always called my OnReps explicitly after changing the value, is that not needed?

[quasi tide]

On server, it is.

I just do a HasAuth check here and then do it. Server spawns everything, so server will always have auth

[weak linden]

I thought so, so it's still a good idea to guard it then?

👌

[quasi tide]

I also pretty much only work with listen servers.

[weak linden]

I always second guess things now, I've learnt a ton of stuff in the last week, stuff I thought was correct for the last 5 years 🤣

[silver pendant]

Hi Chat

[quasi tide]

ACoolActor::SetTheProperty(bool NewProperty)
{
    TheProperty = NewProperty;
    if (HasAuthority())
    {
        OnRep_TheProperty();
    }
}

ACoolActor::OnRep_TheProperty()
{
    UpdateUiDelegate.Broadcast();
}

👆 This is my general flow.

I pretty much always update my UI with a delegate. So, the listen server will update the UI correctly as well as clients. Won't matter on dedicated server, just nothing will be subscribed to the delegate.

[hexed pewter]

Any way around UI not updating immediately because OnRep_ / replication drags behind for whatever reason?
iirc replication isn't guaranteed to be up to date at any given time.

[quasi tide]

You locally predict and then do more custom logic inside of the onrep on if you accept the servers value or not

Most people are okay and understand why UI could take a second to update if they are lagging

[hexed pewter]

Now that you mentioned lagging I wonder how often do replicated variables skip a value or lag behind considering stable internet connection and decent ping 🤔

[green fjord]

hello im hans from Indonesia.
i want to ask about replication pawn between client and server.
when i set actor location on pawn actor in client instance, the pawn actor on the server instance doesnt move. But when the client call custom event RPC run on server and set actor location the pawn actor move on the both instance (client instance and server instance) but in client instance the pawn move is not smooth.
how to achieve smoothness set actor location between client and server ?

i already try to set actor location first on client instance and every tick i call rpc (on server) to send the actor pawn location. but it still caused rollback movement because the server has a delay latency to client so the location that client send was "the past" pawn location on the server

[short arrow]

@green fjord are you making your own movement system by setting the actor location every frame?

[green fjord]

yes that is correct

im working on multiplayer VR, because my VR character is made from pawn

[short arrow]

As far as I know... That is going to be a big challenge. Smooth replicated movement requires a lot of calculation, prediction, and algorithms. Are you unable to make your players a character? I don't really know how vr programming works

[green fjord]

yes I have considered that. I thought there might be an easier way than resetting the pawn actor to the character actor. but thank you very much for your answer, I will try to change the pawn actor to a character actor

[short arrow]

there really shouldn't be any issue converting a pawn to a character, if you need any help please ask. Also I do want to make it clear that I'm no expert on movement, someone may possibly come along soon and tell you something different. But when you look at Character movement component's code... It's complicated, and it's big, and there's a reason for that lol

[pastel fiber]

Which part in UE source code makes AActor::TakeDamage() execute only on servers?

float AActor::TakeDamage(/**/)
{
    float ActualDamage = DamageAmount;

    UDamageType const *const DamageTypeCDO = DamageEvent.DamageTypeClass ? DamageEvent.DamageTypeClass->GetDefaultObject<UDamageType>() : GetDefault<UDamageType>();
    if (DamageEvent.IsOfType(FPointDamageEvent::ClassID))
    {
        FPointDamageEvent *const PointDamageEvent = (FPointDamageEvent *)&DamageEvent;
        ActualDamage = InternalTakePointDamage(/**/);

        if (ActualDamage != 0.f)
        {
            ReceivePointDamage(/**/);
            OnTakePointDamage.Broadcast(/**/);

            UPrimitiveComponent *const PrimComp = PointDamageEvent->HitInfo.Component.Get();
            if (PrimComp)
                PrimComp->ReceiveComponentDamage(/**/);
        }
    }
    else if (DamageEvent.IsOfType(FRadialDamageEvent::ClassID))
    {
        //...
    }

    if (ActualDamage != 0.f)
    {
        //...
    }
    return ActualDamage;
}

[chrome bay]

Nothing, you can run it client side if you want (but not from Blueprint)

The engine just expects you to call the "take damage" functions from the Server only, but it doesn't enforce it.

Apart from in Blueprint, where all the damage functions are tagged as "BlueprintAuthorityOnly" so won't run on network clients

But if you're making MP games in Blueprint you've already lost tbh

[pastel fiber]

Should Super::XYZ() be invoked when overriding?

• Super::Tick(DeltaTime); Yes
• Super::BeginPlay(); Yes
• Super::TakeDamage(/**/); ????

[weak linden]

Typically, yes, unless you explicitly know why you don't want to call it

[green fjord]

in blueprint character how to check if this character is my character or other player's character that replicated on my instance?

[fathom aspen]

IsLocallyControlled

It's LauraControlled

[winged wave]

what are the best practices to make your game communicate with a backend? Would something like regular HTTP requests to an ASPNET Core endpoint be ok or you need more specific workflows? I'm talking mostly about data retrieval if you are building a multiplayer game

[latent heart]

Just be careful. People will reverse engineer your api and try to cheat.

Unless your http communication only happens from dedicated servers which are not available to the public.

[twilit radish]

Unless you don't strip out the requests / code properly lol.

Although really depends on how big your game is, small games tend to not have those issues. Except just random bots that crawl through the entire internet.

[winged wave]

ok thanks, for sure I will have to research on this topic

[twilit radish]

Is this the MMORPG version of how to deal with locally controlled characters? 😛

[fathom aspen]

Yes, made in BP-only

[twilit radish]

Oof.

[latent heart]

It has a wizard button, right?

[mortal mica]

haha, that's my fav gif of all times

[meager raptor]

Hi everyone, I have an actor component on my character pawn. Is there a way to know if it is local ?
My goal is that the actor component should act a certain way only for it's owner. I have tried "Is Actor Local" but it doesn't work on the owner (always return false)

[fathom aspen]

Never seen "Is Actor Local". I've seen this instead: #multiplayer message

[meager raptor]

Well I'm in blueprint so I'm kinda fucked :p. But I think the issue I have is to access my pawn from the actor component so I would be able to know if I'm local. I wasn't able to use IsLocallyControlled since I need to access the control which I don't have access to (I think)

[fathom aspen]

That has nothing to with BP though. It's literally GetOwner -> Cast to Pawn -> Check if IslocallyContrrolled

[meager raptor]

ok let me check

[fathom aspen]

Though that might fail due to the pawn not being possessed yet by a PlayerController

Depends on what point in time you check that

[meager raptor]

in the begin play of the actor component

[fathom aspen]

Yes that smells bad

[meager raptor]

lol

thanks 🙂

mmm

[fathom aspen]

BeginPlay for pawn or its comp fires before a pawn is possessed usually

[meager raptor]

so if I just create an event that I call from the pawn it might be best

from the pawn I can verify if my local

[fathom aspen]

The component is added before runtime, right?

[meager raptor]

I'm not sure

[fathom aspen]

Is it a replicated component that is spawned during runtime?

Or was it added through the simple construction script before runtime?

[meager raptor]

it is a replicated component that is added by default in the character blueprint

[fathom aspen]

So yeah it was added before

[meager raptor]

ok

[fathom aspen]

Then it should be there if you fire client RPC called from event Possessed that accesses it

Or you could have a replicated property that tells that your character is possessed and your component just listens to it

[quasi tide]

Is WizardCell back? 🤔

[fathom aspen]

I don't like both approaches but that's how it is in BP

[quasi tide]

Or is this just in passing?

[meager raptor]

I will try this 🙂

[fathom aspen]

In cpp it's much more neat

[meager raptor]

yeah I bet, since it's for a prototype we will try that dirty way 🙂

[fathom aspen]

It's me trying to cope with the easy problems, so I forget the harsh problems I've been going through recently 😔

[meager raptor]

you are a smurf !

[real ridge]

Guys How I can change normal thirdperson character for plane in game? in MP bcs when I used pawn I didnt see other players seems like pawn is not replicated

when I use normal Character I see others but I need play as (human) I wanna replace it with plane

[real ridge]

Question is just if I should make plane from Character or try to replicate pawn which totally good fit for plane

[real ridge]

bcs now when I join session with 2 pawn I dont see each other 😄

[fleet viper]

was fiddling around with the packetlag command and set it to 200. Does this represent a ping of 200?

[latent heart]

Probably a ping of 400. Since ping is round time, not a to b.

[pallid mesa]

making a plane from a character feels so cursed, but it could work

it depends on your requirements

[real ridge]

yes I know its curse but I have problem my already finished pawn(my plane) is not replicating on session when I join session I dont see each other but when I test from editor and run 2 instances of clients and listen server is behind I See each other

I dont understand

[pallid mesa]

cause pawns, unlike characters, dont bundle with a replicated movement component

you have to make your own

[real ridge]

they are in but they are not visible for each other

but when I try run as Net Mode: Play as Client and I run 2 instances

they are visible

[real ridge]

why I see them then on PLay as client

? its also server @pallid mesa

[pseudo merlin]

hi all, when my listen server host possesses a pawn the controller inherits the pawns rotation. when a client possesses a pawn the pawn inherits the control rotation. what might cause this difference?

I see the controller gets set to pawn rotation in OnPossess, but that might be server side only?

in general when server sets client controller rotation does that trickle down to client machines, or does that get overrwrote on server side next update from client?

[pseudo merlin]

setting control rotation to match pawn rotation on clients acknowledgepossession function seems to help

[prisma snow]

I find it more useful to use the editor network emulation to setup the values

[fleet viper]

Isn't that the same?

[prisma snow]

Yeah but I found it quicker to iterate and also more detailed. You can setup differebt settings for client and server for example. I am sure the command does the same, but maybe it is less intuitive

[fleet viper]

I see

[quasi tide]

Just never leave the "bad" profile. Boom problem solved. Design your game around 200 ping and surely 30 ping will be fine, right?

[prisma snow]

I actually do that, also test with like 700 ping

[quasi tide]

Nah - 700 ping is in the realm of the player's problem, not mine 😅

[prisma snow]

I know but sometimes it helps to detect hard to catch problems

[dry orchid]

Hi I am having problems with my code I think

i am trying to add an impulse to my pawn's mesh but for some reason i cant make the server read the clients rotation

void UAction_CanicaLaunch::StopAction_Implementation(AActor* Instigator)
{
    Super::StopAction_Implementation(Instigator);

    ASCanicaPawn* Pawn = Cast<ASCanicaPawn>(Instigator);
    if (Pawn)
    {

        GetWorld()->GetTimerManager().ClearAllTimersForObject(this);
        
        GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Green, "Stoping Impulse");
        bIsPressed = false;
        if (!bIsPressed && Pawn->HasAuthority())
        {
            FVector RotationVector = Pawn->GetControlRotation().Vector();
            DrawDebugLine(GetWorld(), Pawn->GetActorLocation(), RotationVector*5000.f, FColor::Red, true);
        }

        Impulse = 0.f;
        GetOwningComponent()->OnActionStopped.Broadcast(GetOwningComponent(), this, Impulse);

        
    }
}

anyone knows why is this happening?

that action is called once by the client and once by the server but only the server can add the impulse (i havent add the code for impulse yet)

[deep island]

Have you tried using GetBaseAimRotation() instead of GetControlRotation()? If I remember correctly, GetControlRotation() is ZeroRotator on the server

[visual flint]

Im using UE 5 with Data layers, I cannot figure out how to implement a loading screen and determining when a data layer is loaded. Im trying to add a dungeon to my game where an individual player loads the dungeon data layer while another player is roaming around the over world. I cant figure out from the docs a good solution, does anyone know of some good multiplayer data layer resources?

[sonic python]

Hey Me Again

When I press a button ,($10) I want to make a in app purchase

How to do that

And the product is just some integer var

[prisma snow]

On button press, send an RPC with the player controller to the server. Validate that the player has enough money, the product is available etc, then do the corresponding changes in the state (whatever they are) and replicate the state back to the player if necessary

@sonic python

[sonic python]

Oh not that

I want to know abt that Make In App Purchase, Read , Restore...

When I press the button

[prisma snow]

Purchase what

[sonic python]

A custom event in game instance happens

Which is add game currency

[sonic python]

The Game Currency

[latent heart]

He wants to add a button to spend real world money to buy ingame currency for his mobile game.

[prisma snow]

Ahhh and he asks here

LOL

[sonic python]

Yep Correct

[sonic python]

Oh Sorry Didn't See Multiplayer

Do you know where should I ask?

Epic - online - services?

[latent heart]

That's not related.

[sonic python]

Online subsystem?

[latent heart]

Or that.

#mobile probably

[sonic python]

Ohkay

[dry orchid]

tried that now bust still is not getting the correct rotation

[deep island]

Have you tried debugging the values of the rotators?

What are the results?

[dry orchid]

On the client is always X: -1, Y: 0.0, Z: 0.0

for the server

[deep island]

That's not good, it seems like there is a problem with the rotation update code

On the server do you have the same result?

[dry orchid]

no, in the server it changes normally

[deep island]

If you use the GetControlRotation() method do you have that value on client? Or the right one?

[dry orchid]

im gettin that one too

but i have an error when i compile

ObjectProperty FActionRepData::Instigator is not initialized properly. Module:Videojuego_Canicas File:Public/SAction.h
Display LogClass BoolProperty FActionRepData::bIsRunning is not initialized properly. Module:Videojuego_Canicas File:Public/SAction.h
Display LogClass 2 Uninitialized script struct members found including 1 object properties
Warning LogAutomationTest ObjectProperty FActionRepData::Instigator is not initialized properly. Module:Videojuego_Canicas File:Public/SAction.h

maybe that is what causing it?

[deep island]

You have to check that SAction.h at the specified row

Have you initialized bIsRunning correctly inside FActionRepData?

And Instigator too

[dry orchid]

USTRUCT()
struct FActionRepData
{
    GENERATED_BODY()

public:

    UPROPERTY()
    AActor* Instigator;

    UPROPERTY()
    bool bIsRunning;
    
};

thats how i wrote the struct

[deep island]

Make a default constructor

FActionRepData()
{
bIsRunning = false;
Instigator = nullptr;
}

Under bIsRunning;

And try to compile

[dry orchid]

ok i got rid of the error, thank you

also i have this one

Failed to load '/Game/RollingCPP/RollingOverview': Can't find file.

not sure what that is

but the rotation is not updating correctly yet

[deep island]

I don't know what RollingOverview is, but something is trying to load it from the Content folder

[deep island]

What is the Rotation value with GetControlRotation()? Do you have that -1, 0, 0 vector again or the correct vector pointing in the right direction?

if GetControlRotation() is working on the client, you have something not working with GetPlayerViewPoint(), which is the function used by GetBaseAimRotation() to get the player's eyes view point

At the end it should use GetControlRotation() anyway on the local client, because it's calling GetViewRotation() on the pawn, which returns GetControlRotation() if the Controller is not null

[dry orchid]

that one is with GetControlRotation()

the blue one is de client and the green one the server

bool USActionComponent::StopActionByName(AActor* Instigator, FName ActionName)
{
    for (USAction* OtherAction : Actions)
    {
        if (OtherAction && OtherAction->ActionName == ActionName)
        {
            if (OtherAction->IsRunning())
            {
                if (!GetOwner()->HasAuthority())
                {
                    ServerStopAction(Instigator, ActionName);
                }
                
                OtherAction->StopAction(Instigator);
                return true;
            }
            
        }
    }

void USActionComponent::ServerStopAction_Implementation(AActor* Instigator, FName ActionName)
{
    StopActionByName(Instigator, ActionName);
}

that is how i wrote the code in the action component calling the action

and that is why is been call 2 time in the picture

[dry orchid]

it seems the server is not updating the rotation

but when the server is calling the action

[fiery wadi]

Probably a dumb question but i cant seem to find a google response, How would i use Get Ping In MS from the server ? I know its from the Session Class but im not sure how i access the server's session. ?

So i have it atm the player clicks Host Session and Goes tto the lobby area and I want to show the servers ping in a scroll list Player A : 12ms, Player B 35ms, Player C 100ms etc. (Player A would be the server itself in this instance)

[prisma snow]

I know you can access the Ping via the player state iirc

[fiery wadi]

Get Player State - > Get Session -> Get Ping In MS? something like this.

[prisma snow]

Not sure how it is calculated exactly, it is not a trivial calculation

[prisma snow]

I have the code somewhere, wait a sec

[fiery wadi]

Thank you

[prisma snow]

It's PlayerState->GetExactPing()

[fiery wadi]

Ahh thanks !

[deep island]

Hmm, I don't know, it's not clear what it's happening

What's that Server: 0.0 print string?

[dry orchid]

ah thats the impulse i am adding. it has nothing to do with the rotation

[deep island]

@dry orchid ok, in the last screen the green and blue values seem correct (except for the first blue one, but I don't know where it comes from), so what is not working?

[woeful ferry]

Yo guys,

Just wanted to know I just released a nice resource for the BP multiplayer community, where BP projects can replicate UObjects without having to use c++. I don't know if I'm allowed to send marketplace links here 😅

oh yes 😛 I'll let people go there instead.

Posted there now, if people wanna check it out ^^

[dry orchid]

the first one is coming from a OnRep that is been called wuehn the server runs the action

in the last pic is the server, the server is working well

[dry orchid]

thos one is the client. when the client runs te action it has the correct rotation but when the server calls the action trough the RPC

the rotation goes to 1 , 0, 0'

dont know why

[deep island]

is OtherAction->StopAction() calling this?

[dry orchid]

yes

[dry orchid]

yes it s

[deep island]

Maybe there is something else that sets a bad rotation in your code, anyway I don't know what to think, if the server is getting the right rotation, it should work, and if you have the right rotation on the client too, why when you call an RPC should the rotation be different?

You need to debug the code and see where the things are breaking, maybe you can even debug the engine code and see what's wrong there

I mean, the engine code usually works, but maybe you are passing bad things somewhere, and it's returning something wrong in those functions

[plush wave]

Ok so for vehicles

Is it better for them to simulate physics and replicate

Or better to have a custom component and fake it

[dark edge]

Depends™️

If you're game is meant to be a physics playground then use physics. That's what I'm doing.

If it's meant to be vehicles GTA style then fake it

[plush wave]

Hmm

[dark edge]

This is what I got going on if you want to take a look. It works in multiplayer but I'm NOT doing prediction as that'd be an entire can of worms. So there's ping delay between inputs and the vehicle doing the thing.

https://www.youtube.com/playlist?list=PL8IUriowVVYEDj4oSctoxA4U1lOE70z08

[plush wave]

Yeah, super interesting, thanks

so why the ping delay?

[pallid mesa]

because it doesn't have prediction

[dark edge]

So I don't need to do prediction on player-designed vehicles which would be an absolute career in and of itself.

prediction is bad enough when you know the limits of what the pawn can do

when it's people building big kerbal twisted metal style contraptions it'd be a nightmare

[prisma snow]

I find it really hard outside of very specific contexts. FPS predicition is quite figured out and Rollback as well for fight games, but for other simulations I find it really complex

[dark edge]

Yeah now imagine prediction a garrysmod style contraption

no thanks lol

and even with great prediction you always have trouble when it comes to pawn to pawn collisions

I'd rather just have the delay and be done with it. It's not a racing game, it's not like tanks and artillery really need to respond THAT quickly

[prisma snow]

yeah, anything that resembles physics is a nightmare

[plush wave]

Rocket league seems to do it well

[quasi tide]

They're also big 🧠

[prisma snow]

Even without prediction physics replication is a nightmare

[dark edge]

Rocket league spent probably thousands of engineer hours on it and their vehicles are very predictable and are basically spheres in a vacuum

[plush wave]

Right

[dark edge]

What I'm trying to make is closer to Kerbal Space Program with engines and tires and it's already a nightmare since everything is so nonlinear.

[prisma snow]

Ye. Also Frost Giant is doing prediction (via rollback) for Stormgate, but good luck assembling a team that can do lockstep, let alone lockstep and rollback in a RTS context

[plush wave]

Guessing GTA5 is similar?

[dark edge]

There's a reason why we had great flight and space sims decades before realistic driving physics. Tires are hard man.

[prisma snow]

Do players feel the difference when playing a modern vs older driving game (in terms of more complex physic simulations)? I almost never played driving games and never in multiplayer

[undone kindle]

What information should be on player pawn vs. player state vs. game state?

I'm making a single player game, but trying to get used to doing things the "right way" for when I do a multiplayer game in the future that will require network replication

Reading the docs, and network compendium, but it's still not clear to me

My instinct is that everything player related should go on the player state

[undone kindle]

Awesome thanks!

[neon mango]

Is there a known bug in 5.1 that shows black screens for clients?

[woven basin]

not specifically that I know of. I use 5.1 and my clients connect. You'll need to check your logs etc.

[dark edge]

Key word is player related, not their pawn related

Score is on player state. HP is on pawn

[summer tide]

Can you create multicast methods in UAnimNotifyState?

[worthy knot]

Does UE's default voice chat even work ?

proximity voice chat

[short arrow]

yes, but I hear it's terrible. It's supposedly very capable of crashing servers

I've used it once for a small multiplayer game I made and it worked fine. However the quality was terrible, like even worse then Apex legends

and apex legends voice chat quality is straight booty

[worthy knot]

Disgusting

[winged badger]

you can but those won't be replicated, so multicasts won't work

[prisma snow]

Is it possible/advisable to build a net system such that bandwidth is "manually" limited?
Let me explain the context. After some tests in real conditions, I am quite sure that our current replication system for RTS is viable with relatively big unit counts. However, it is not very efficient or smart, in the sense that it basically updates all units equally no matter the context. After some research, I came again into Glenn Fidler's articles about networked physics, and the "state synchronization" approach that he describes fits our usecase really well. He describes the idea of a "priority accumulator" (an array of items with a dynamic priority, which gets sorted each time that we are doing an update).

The basic idea is that you define a max size for the update, and pick items from the array starting with the highest priority, until all items are picked or the max size is reached. In this way, important items get updated more frequently, but never exceeding a certain packet size

Since internet connections are quite variable, and I am not sure that it is easy to automatically detect the connection strength as to define a different max limit for each player, I was considering putting a setting that each player can pick or similar. But still, I am not sure that is a good approach

[winged badger]

that can come around to bite you

without a panic mechanism

and it is more or less what unreal does for replicating actors already

what are you units in gameplay framework terms, and how much data is there per unit?

[prisma snow]

Units are MassEntities, basically. There are Pawns on top of them which have some AI logic and combat stuff (GAS), but all the movement is handled manually in Mass and the position replication (which is the one I mention) too

[winged badger]

how many players?

[prisma snow]

Each unit has a 16bit ID (same for server and clients), and positions are compressed to 16bit for X and 16bit for Y

For player count, ideally up to 8, but to be honest reaching 4 would be already enough.

And unit count, max 2k, although usually it's going to be between 100-500

[winged badger]

c++ ?

max 2k means no character movement components or something crazy like that?

[prisma snow]

Yes, ofc

[winged badger]

with c++ and simplified movement components, i'd go for dedicated actor for replicating units per connection, relevant only for that connection

[prisma snow]

Yes, no cmc

[prisma snow]

That is not viable, I tried it at the beggining but 2k open actor connections was horrible

I need to replicate through a helper actor, that is totally necessary

[winged badger]

in it, i'd put a fastarray for each interface a unit might need to replicate stuff from, plus one for the basics, (ID, position)

every fast array item would have either an ID or a weakpointer to the unit pawn if you can make those net addressable

and i'd turn off unit replication off completely

[prisma snow]

yeha that's already done

[prisma snow]

yeah, I also do that (manually) via a id generator, that the server uses when spawning entities

currently, each unit gets updated once per second, so thats 16+16+16 * 2000 = 96kbit/s

[winged badger]

how are you replicating the data?

[prisma snow]

dunno how crazy it is honestly, a 2 player test we made with 1k units ran well

[prisma snow]

right now, sending an unreliable RPC every 100ms, with 1/10th of the unit count (so 200 unit array 10 times)

[winged badger]

try a fast array, i don't think it will have a problem handling that

[prisma snow]

But from testing, there are times where the update is just not necessary, and others where more frequent updates would be benefitial

that's why some variable approach sounded appealing

[winged badger]

fast array will only send over items you have marked dirty on server each update

[prisma snow]

yeah that sounds useful. Also will solve the issue of rpcs, which sadly are kot stateful so

I'll give it a try and make some tests

also I'm making some tests to see if sending full position is worse than sending deltas

[winged badger]

i don't think there will be any difference there

[prisma snow]

that means that I could mark items as dirty on a timer and trigger the replication manually even, if I don't want to replicate asap. Can you throttle bandwith/replication for a single actor/property?

[winged badger]

my network managers are handling literally thousands of actors, and never had a single hitch

[prisma snow]

same but going to try

[prisma snow]

that's nice to know!!

[winged badger]

basically

[prisma snow]

how many thousands, and how many players?

[winged badger]

8 players, can have 6-7k actors if someone dropped a nuke

and never had a problem with hotjoining after either

[prisma snow]

do you have dedicated servers?

[winged badger]

note that my actors don't need such frequent updates

no

but basically, whenever something above some significance threashold happens

[prisma snow]

Yeah I understand, but I also think that we don't need, just in some specific scenarios (big battles in concrete spots)

[winged badger]

you update its item in the array and mark it dirty

there is also oodle built into UE5

that should help too

[prisma snow]

ye I was planning to make some system to detect "hot areas" (basically spots where combat is likely to happen) and focus updates on that

[prisma snow]

yeah I want to use it, but wanna see if what we are making is viable before extra compression

[winged badger]

basically, for movement

if the player did not change the move order

[prisma snow]

I also was considering writing a serialization system for those 16ints bcs many times I can get away with less

[winged badger]

and nothing else interfered with the unit

its movement is quite predictable

and would not need to be updated

[prisma snow]

what I realized in our context, is that even if units collide between them (with no combat involved) the only difference is that they arrive to location slighlty later. Not even noticeable unless playing with 2 screens and slow mo

So positions only get out of sync when cluster collision scenarios happen and even then it is not important unless we are fighting

[prisma snow]

There's a detail about the FFastArraySerializer that I don't find clarified, when they say it does "delta" updates, do they mean:

1. Only the dirty structs are replicated, not the whole array
2. Only the changed properties from the dirty structs are replicated
3. Only the change/diff between the changed properties of the dirty structs are replicated.

So if I have a struct with int A = 10 and int B = 5, there is a change and now B is 6.

What will he actually be sent across the net, the two values, only value B, or the old B value minus the new one (in this case, a single 1)

[thin stratus]

I can at least say that the third option is not correct

That wouldn't make sense for other properties :P

[prisma snow]

Yeah, I was quite sure of it but one can dream

[thin stratus]

I think it sends the element itself. But not sure if that gets cut down even smaller by only sending the inner property that changed

[prisma snow]

I'm gonna make some tests so I'll test that as well

[winged badger]

you can manually implement delta serialization on fast array item

[prisma snow]

yeah, I'll do if there is a real benefit. Deltas have the added complexity of ensuring that the past state to compare with is valid

[quasi tide]

@winged badger Just caught up - are you saying you are replicating like 1K+ actors that are moving around and what not through your network manager?

[prisma snow]

Yeah, I could make 1k without many issues, and without compression

[quasi tide]

I'd imagine yours comes from a more simplified movement component though, no?

(I'm always lookin' for ways for maximum zombies 😈)

Even if I don't actually need it

(I already knew about network managers, as an FYI)

Just getting them to work with movement, hadn't tried 😢

[prisma snow]

A MassEntity-based movement simulation. It is all 2D, uses boid rules to get complex behaviour, and also handles collisions

[distant turret]

with EOS plugin is it possbile to create a chat system

[prisma snow]

CMC is very heavy

maybe the floating pawn component is more performant for zombi hordes

[quasi tide]

Ahh - nah, CMC is fine for me honestly. I only plan on having like, max, 40-ish for this zombie game I'm doing. But I always enjoy pushing things 😅

I already know that I'd want to do an entirely custom movement component if I wanted to go much higher.

[prisma snow]

ohhhh then CMC is perfect

I think CMC fell appart in mp when we had something like 100 units

but that was default settings

[quasi tide]

Yeah - I'm doing more Resident Evil scale 😅

[prisma snow]

maybe with a much lower update rate and appropiate settings it can do more

also if it is a 1st/3rd person game, only the zombies that are close are reslly relevant so you can optimize around that

[quasi tide]

Yup

[winged badger]

we can do 200-250 CMCs

but that took some doing

[undone kindle]

Should PlayerState be a glorified bag of properties that are public read/write accessible and let the GameMode handle validation, or should it validate its own data with custom setters so that health can't go below 0, etc.?

[quasi tide]

Do as much on the client as you can

PlayerState should be things that you want other people to know about the player as well as pawn agnostic things

You could have health in there as well mind you. You just have to reset it when you get a new pawn and handle the current pawn when it gets <= 0

[latent heart]

No properties should be public. You should use getters and setters.

Unless they're (static) const.

(except maybe on structs :p)

[undone kindle]

Why not have public properties? If I will be handling validation on the game mode. Because the getters and setters will just be transparent return statements or member var assignment.

[latent heart]

It will just cause problems later.

It's not necessarily about validation (though it could be), it's more about having some buffer between the code setting the variable and the variable being set, so you can add callbacks or validate or whatever.

It takes no time at all to add a setter/getter, but it takes ages to adjuts code when you need to add them after the fact.

[undone kindle]

Oh that makes sense, so like if I want to broadcast a change in player health. Better to just mediate through getters/setters so the interface is set up for it from the beginning

[latent heart]

Exactly!

[quasi tide]

#cpp message

This is my reply to someone who was asking why you technically should be using SetRootComponent() instead of just RootComponent =. Take the same logic and apply it to your own code.

[undone kindle]

This made me chuckle. So basically we know we should be using getters/setters for everything, but we can't be arsed?

[quasi tide]

1. Know the rules
2. Evaluate if you give a care about said rules 😈

If it is my code - I do w/e I want. It's my travesty. If I'm working on a team, I do it the "correct" way.

For my own code - I can count on one hand how many times I've went back and was like, "Dang - I really need to do additional logic for this field"

(Not saying I don't use getters/setters mind you)

[candid shuttle]

Hi guys, I need some help on an issue I am having:

So I have a PauseMenu where a button can make a player leave the lobby or, if it's the server, destroy the session (means = kick everyone). Now when I use this button in my LobbyLevel everything works fine but when clicking while on GameplayLevel everybody gets kicked even when a Client uses the button, which certainly should not happen.
I couldn't find anything on Reddit or the ue4 forum so I attached some pics of my BPs:
(The branch I used after my MultiplayerLeaveSession Event is copied from a forum post but doesn't really do anything the DestroySession node wouldn't handle on it's own)

Thanks for any help in advance

[candid shuttle]

Without multicast it's the same. And the Multicast just fires if it's the server, which works fine, but the problem is on the client

And Multicast can't be fired from a client

[thin stratus]

I mean

You shouldn't destroy sessions like this anyway

If the Server crashes or similar, the Clients will be booted to the MainMenu without calling this

You aren't catching all edge cases with this

And a Client with a Session can't Join or Host anymore

[candid shuttle]

This also gets fired on EndPlay

Does this help?

[thin stratus]

Maybe, but best is to just Destroy it in your MainMenu GameMode and/or before calling Host/Join/Search

Either way, you also wouldn't need to multicast this

If the Server leaves, the Rest is moved to the MainMenu anyway

• the Server might also leave before the RPC is even processed, and the Clients will be moved to the MainMenu naturally anyway

It's just not the safest/cleanest way

[candid shuttle]

The session even gets destroyed in the MainMenu just for safety reasons you mentioned. But even removing the Multicast doesn't remove the problem

[thin stratus]

Hm, strange indeed

[candid shuttle]

Ok so I should just do a OpenLevel?

[thin stratus]

I would try

Not sure why it would boot everyone though if just a client calls it

[candid shuttle]

Still the same problem

[thin stratus]

What does your log say

[candid shuttle]

I am testing it in the editor but had a friend tets it once packaged and the problem persists

[thin stratus]

Opening level as Client should not disconnect anyone but that Client

[candid shuttle]

When I just open the level without a DestroySession in the MainMenu it still disconnects everyone. And this problem only appears after switching from Lobby to Gameplay Level.

[thin stratus]

But.. when you are testing multiplayer

In PIE

And you travel

That means you aren't using Seamless Travel

Which is kinda bad

99% of the time you should Seamless Server Travel

And that is not available in PIE

[candid shuttle]

I use servertravel for Lobby->Gameplay Level

Is this seamless travel?

[thin stratus]

Yeah, but if you can travel in PIE that means you aren't Seamless Traveling

No it's not by default

Seamless has to be enabled on the GameMode you are travling with

[thin stratus]

It also changes a lot of the functions that are called

E.g. PostLogin in the GameMode doesn't call for this

And CopyProperties in the PlayerState is now available to move data over

Yeah

You can't do that in PIE though, it's disabled

And some Subsystems, like Steam, require this

Otherwise your Clients disconnect on Travel

[candid shuttle]

Yeah i see, so I need someone to test this with?

[thin stratus]

Or rather

Don'T reconnect

No, you just need to do it outside PIE

E.g. by starting standalone

or rightclicking the Uproject file and launchign the game

Or even packaging fwiw

Usually, once the traveling is "working", one only works in the current map in PIE anyway

So it's not too big if a hazzle

[candid shuttle]

So I need to disable steam subsystem?

I'll try that

[thin stratus]

No, that was just a side comment

[candid shuttle]

I did need to disable SteamSub, but the problem persists still. Do I need to call something else then OpenLevel eg servertravel

[thin stratus]

Not for Disconnecting

Only if you want to travel from Lobby to Gameplay, Gameplay to Gameplay or Gameplay to Lobby

And only on the Server then

[candid shuttle]

what do I need to call if I want to seamlessly leave the gameplay section as a client?

still OpenLevel?

[thin stratus]

OpenLevel

[candid shuttle]

Because that doesn't work either, kicks everyone

[thin stratus]

Can you test that in Standalone ?

[candid shuttle]

That was in standalone

[thin stratus]

Then you'll have to look at the logs of everyone

And see why they leave

[dry pebble]

Have an issue where server and client are in the correct custom Movement Mode (climbing) but simulated proxy knows we're in the right movement mode for one frame, then exits it to the falling logic. Even though the server knows we're still in the climbing mode. Any ideas for that?

[latent heart]

I would say find out what's changing the mode to falling.

[thin stratus]

Iirc SimulatedProxy still runs its own simulation of the movement code

[latent heart]

@undone kindle another reason setters are good ^

[thin stratus]

So it could indeed manually decide that it's falling

Cause it might be missing some information

Given most of the time you only share information between server and autonomous

You might just have some condition to start falling that is never false for the simulated, cause you rely on something only those two know?

Just a wild guess

[dry pebble]

This is what changes it to falling in PhysClimb()

        if (ShouldStopClimbing())
        {
            StopClimbing(deltaTime, Iterations);
            return;
        }

If I comment this out, the simulated proxy knows we're in climbing and never leaves it. But if I leave it on server + client say climbing and sim proxy says falling.

And this is:

bool UMMOCharacterMovementComponent::ShouldStopClimbing() const
{
    const bool bIsOnCeiling = FVector::Parallel(CurrentClimbingNormal, FVector::UpVector);
    
    return !Safe_bWantsToClimb || CurrentClimbingNormal.IsZero() || bIsOnCeiling;```

And
```cpp
void UMMOCharacterMovementComponent::StopClimbing(float deltaTime, int32 Iterations)
{
    Safe_bWantsToClimb = false;
    SetMovementMode(EMovementMode::MOVE_Falling);
    StartNewPhysics(deltaTime, Iterations);
}```

And Safe_bWantsToClimb is only set to true when I click "E" and face a wall. I never set it to false

And it's added to compresed flags etc too

[latent heart]

I'm gonna assume b_WantsToClimb is false on the simulated proxies. or the normal is zero.

[dry pebble]

But isn't PhysClimb not called on sim proxies? only server and client?

And only movement mode is replicated? (+ velocity, acceleration etc.)

And yes Safe_bWantsToClimb turns false which exits to falling state, the rest remain the same in ShouldStopClimbing() when I break point it.

[latent heart]

Then it's calling should stop climbing on the simulated proxies and causing the error. Maybe add an owner check to changing movement modes?

[dry pebble]

nice idea, will try it!

[thin stratus]

Pretty sure Simulated runs some code too

[latent heart]

Role != SimulatedProxy or whatever

[dry pebble]

CharacterOwner->GetLocalRole() != ROLE_SimulatedProxy)

[dry pebble]

Oh really? I thought I heard someone say only server + local client runs it, but I could be wrong

OMG IT WORKED!

Adding the simulated proxy check 😄

Normally the red circle would say "Falling"

thank you so much!

I gotta go read up about sim proxies running physics functions now lol

[latent heart]

It doesn't make sense for simulated proxies to be changing movement modes themselves anyway, so this is probably a good general fix.

[dry pebble]

exactly, server should change the movement mode to send to sim proxies. Now I wanna make sure I always have that check

[candid shuttle]

The OutputLog or the one that appears when openinga standalone game

because both display nothing when leaving

[undone kindle]

Since PlayerState and their Pawns are replicated to all clients, does that mean a client can see other player positions through walls using some client-side patch to the game (aka "wallhacks")?

[latent heart]

In theory, yup

[candid shuttle]

That’s how Wallhacks work fundamentally

[latent heart]

If you're super concerned about that, you could be very strict on relevancy.

It will delete actors and not replicate changes when actors become non-relevant.

Well, maybe the delete part. Probably delete.

[fathom aspen]

If they are dynamic net actors they will get deleted

Which is the case with pawns

You can take a look at what Valo did

https://technology.riotgames.com/news/demolishing-wallhacks-valorants-fog-war

[dry pebble]

So I just added this to my PhysClimb functions so none of this code runs for simulated proxy and everything works. Is there a case where simulated proxies should call the custom Phys functions?

if (deltaTime < MIN_TICK_TIME && CharacterOwner->GetLocalRole() == ROLE_SimulatedProxy)
    {
        return;
    }```

As I notice the while loop in PhysWalking checks if you ARE a sim prox

    while ( (remainingTime >= MIN_TICK_TIME) && (Iterations < MaxSimulationIterations) && CharacterOwner && (CharacterOwner->Controller || bRunPhysicsWithNoController || (CharacterOwner->GetLocalRole() == ROLE_SimulatedProxy)) )
    {```

[undone kindle]

Very cool, thanks for this

[neon mango]

So I have game mode updating game states array of team scores, and team scores is set to replicate but the array doesn't change from their default values?

Server is fine, client doesn't see the updated scores

[fathom aspen]

Probably forgot to tell GetLifetimeReplicatedProps about the array

I don't think UHT rants over you if you forget to do that

[neon mango]

I'm prototyping and doing this all in blueprints. Is this an issue with blueprints and I should try to do this in c++?

[fathom aspen]

Ah, nvm then

I boldly supposed you did it in cpp

[neon mango]

I'll end up moving in. CPP but I'm just prototyping right now and I thought this array replication works in blueprints

Does it matter how you set the array?

[fathom aspen]

I think you have to SET the array in BP for replication to work, prolly just adding doesn't trigger replication?

Cuz I at least know that happens if you use the increment operator in BP it won't

[neon mango]

I tried via the set array element and set by ref

[fathom aspen]

Sorry I'm not a BP geek, and BP is full of networking landmines so I'm just guessing

[fresh cloud]

not for this reason specifically, but i originally did this for the portfolio piece i'm working on. part of my design was pawns shouldn't even be spawn in when they are irrelevant to the client, and relevancy doesn't change often in my design, so when certain factors are recalculated i recheck the replicated actors and close channels on the server. this IMMEDIATELY closes them, and when they become relevant again they pop back in

outside of closing the channel, relevancy still has a threshold time where, after being deemed irrelevant, the channel stays open for a little for the server to be able to preserve it in case it becomes relevant in a short amount of time. this can be adjusted, but i found better reliability in just closing the channel myself

[fathom aspen]

Sad day for my MMO dev career

[neon mango]

So I think it is replicating but there is a delay, of like 5 seconds?

IDK if its an editor testing issue in 5.1 or something else

[fresh cloud]

uh, also i remember reading somewhere that array replication is atomized in UE

so, for example, if an array goes from {0, 0} {0, 1} {1,1}, that exact order isn't guaranteed?

clients might receive the replication in unexpected order

i'm not saying that's the current issue, but it's something to be aware of when replicating an array

... i think

[neon mango]

I switch to float and now testing with int32

notice the delay with iint32 replication

it's getting there but delayed

compiling now to test on individual hardware

Fyi not as an array

[fossil spoke]

@fresh cloud Correct, there is no guarantee that a Replicated Array will be order consistent across Clients.

If you need consistency of order you would need to setup support for that by some other means yourself.

[neon mango]

I can ditch the array right now

Good info

Curious about the delay

[fossil spoke]

What Actor does the Replicated property exist on?

A delay in replication time could mean a couple of things.

[neon mango]

A standard AActor that only server has, then that goes to the game mode to call update score and then sets replicated integers on game state

[fossil spoke]

So they are on the GameState?

Have you checked that the GameStates NetUpdateFrequency is relatively high? A low NetUpdateFrequency can give the appearance of delay when replicating variable values.

Also verify that you arent testing with simulated Latency in the Editor.

This would also contribute.

Keep in mind that a variable will only replicate (by default) if its value has changed.

[neon mango]

Enable Network Emulation is not enabled

[fossil spoke]

Can you repro the issue in a blank project?

What are you using to verify there is a delay?

[frosty dune]

Hello everyone. Having an issue trying to a player's steam ID with a dedicated server.

I see the message on the server after the onjoin "LogBlueprintUserMessages: [DarkRP_GameMode_C_2147482482] Steam ID: 76561198099278132 joined the game."
But when I try and access the SteamID from the player, I get a "Bad Unique Net ID" error.

[fossil spoke]

PostLogin only runs on the Server.

Looks like you are using Keyboard input to fire the event that would print out the SteamID on your InventoryController, this would result in the Client doing this.

In such a case, because SteamID is only set on the server (due to PostLogin) it does not have a valid value on the Client.

You would likely want to Replicated the SteamID variable, or access the Steam Id locally on the Client from the OSS, since the Client should have its Steam Id locally as well.

[frosty dune]

That makes a lot of sense. That's a stupid mistake on my part

[fossil spoke]

The Steam Id should be set on the Client via the PlayerState exposed through UniqueNetId

[frosty dune]

Gotcha. I'll switch that around and give it a shot. Thanks!

[candid shuttle]

Can someone get back to my problem please

[sinful tree]

If you're calling Open Level on a single client, then only that single client is leaving. If you're calling Open Level on the host or server, then it would kick everyone. Did you check the logs to see why everyone may be leaving?

[fresh cloud]

oh also very basic question, but does your host happen to be a listen server?

if a listen server opens a new map, they aren't just a plain client, that will kick everyone too

[summer tide]

What are my options? I don't want to add an Anim instance only for that?

[winged badger]

no, but the anim notify can call a function on something that is replicated and able to MC, like the pawn

[summer tide]

I'm trying to avoid any casting.

[winged badger]

to avoid blueprint dependencies?

you can call a c++ multicast, it really doesn't matter if you cast to native class

they are all loaded at all times

[summer tide]

To keep the integration simple. So no need to re-parent anything.

[winged badger]

sometimes casting is necessary

and interface seems way too much for this scenario

[summer tide]

If I can override a function from notifier in AnimBP that will work but then I have to access the notifier from animbp somehow

[candid shuttle]

So you mean a !listen server gives clients the ability to kick everyone?

[fresh cloud]

yeah, they count as client and server at the same time, if you want them to function as ONLY a client, the server has to be set and dedicated and hosted elsewhere 😦

you can get verification from one of the more knowledgeable members, but to my understanding that's the case

[candid shuttle]

Can I say Bad word

[thin stratus]

Eh

[candid shuttle]

ok sry

[thin stratus]

Not related to the f word

A ListenServer does not provide the ability for other clients to kick

[fresh cloud]

but if the listen server abandons by loading the map, it should kick everyone else right?

[thin stratus]

This whole thing would only work if the ListenServer disconnects. That will then disconnect everyone else cause no Server available.

Yeah but they have the issue that a client causes everyone to leave

[fresh cloud]

oh exi i was asking that under the assumption that the "client" that was causing everyone to leave was a listen server "client"

which in this case would cause that to happen

[candid shuttle]

How can a client be a listen server client? A player that creates a listen server?

[thin stratus]

They are calling locally OpenLevel. I'm pretty sure there is other stuff going on that we either can't see or isn't obvious

I can create a new project now, let 2 clients connect to a ListenServer, and then let one Client leave and it won't break, I'm pretty sure

Otherwise a lot of games would have huge issues

[candid shuttle]

that's what I would think too

but....

my project doesn't wanna do that

[thin stratus]

Yeah but the chance is high that it's caused by code from you

[candid shuttle]

Thats for sure

Does a beginPlay node in a level BP get called from Server or Owning Client, in the MainMenu for example?

Because I now did this and it only prints out 'mmmmmmmmmmmmmm' one time

[sinful tree]

Put a print string on begin play and run as client. If you see the print say "Server: <whatever you printed>" and "Client: <whatever you printed>" that means it'll run on clients and the server.

[candid shuttle]

It does print out Server, Client1 and Client 2 while I am only playing as 2 Players

[thin stratus]

BeginPlay gets called for everyone who has an Instance of the specific Actor

LevelBP would be called for everyone who is on that level

[prisma pelican]

why does pawn's actor get destroyed when on level reset is called, the default implementation shouldnt do this right?

[candid shuttle]

So because the server spawns in first, it fires a print string from the server. Now, I am playing as two clients and no server, how does this work?

[summer tide]

How do you get IsLocallyControlled in AnimInstace?

[candid shuttle]

get owning player of some sort

[fathom aspen]

It should by looking at APawn::Reset

[fathom aspen]

TryGetPawnOwner

[summer tide]

I should be able to access IsLocallyControlled directly in anim instance but i can't

[fathom aspen]

Last I checked I found AnimInstance != Pawn so yes you can't

[summer tide]

I get undefined