Multicast function didn't actually update the property on the client side

I have a multicast function in a BlueprintSCSHook actor component:

UFUNCTION(BlueprintCallable,NetMulticast,Reliable, Category = "Infinite Spline")
void SetLength();

void UInfiniteSplineActorComponent::SetLength_Implementation()
{
    if (AFGConveyorBeltHologram* belt = Cast<AFGConveyorBeltHologram>(GetOwner()))
    {
        UE_LOGFMT(LogInfiniteSpline, Display, "Run on {0}, Length={1}", *NetModeToString(),Length);
        belt->mMaxSplineLength = Length;
        }
}

UFUNCTION(BlueprintCallable,NetMulticast,Reliable, Category = "Infinite Spline")
void SetLength();

void UInfiniteSplineActorComponent::SetLength_Implementation()
{
    if (AFGConveyorBeltHologram* belt = Cast<AFGConveyorBeltHologram>(GetOwner()))
    {
        UE_LOGFMT(LogInfiniteSpline, Display, "Run on {0}, Length={1}", *NetModeToString(),Length);
        belt->mMaxSplineLength = Length;
        }
}

And the logs show that it was executed on both the server and the client side.

Solution:

I mean when you are playing in the game client and someone joins you (no dedicated server involved) this table (unrelated to the issue) shows the "types" of multiplayer

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12 Replies

PiggyChu620OP•2mo ago

FString UInfiniteSplineActorComponent::NetModeToString()
{
    switch (GetNetMode())
    {
    case NM_Standalone:
        return TEXT("Standalone");
    case NM_DedicatedServer:
        return TEXT("Dedicated Server");
    case NM_ListenServer:
        return TEXT("Listen Server");
    case NM_Client:
        return TEXT("Client");
    default:
        return TEXT("Unknown");
    }
}

FString UInfiniteSplineActorComponent::NetModeToString()
{
    switch (GetNetMode())
    {
    case NM_Standalone:
        return TEXT("Standalone");
    case NM_DedicatedServer:
        return TEXT("Dedicated Server");
    case NM_ListenServer:
        return TEXT("Listen Server");
    case NM_Client:
        return TEXT("Client");
    default:
        return TEXT("Unknown");
    }
}

But the belt's max length didn't get changed in multiplayer mode, could somebody please be so kind helping me out? Much appreciated.

Robb•2mo ago

But the belt's max length didn't get changed in multiplayer mode

what happens when you try host and play multiplayer, does it work for the host only? can you check after the fact what belt->mMaxSplineLength is on the client side - is it actually the value you changed it to, or did it somehow get changed back? what is the specific actor your component is being attached to via the SCS hook?

PiggyChu620OP•2mo ago

It worked in single-player mode. I don't understand wdym by "host" tho, set up a dedi server and login as an admin? No I haven't, I thought that since the assignment is executed right after the log, so it should naturally be executed as well, but I'll check it tomorrow. But how should I check tho, log right before and after the assignment? Or write another hook to check the value constantly, probably on the Tick? Spline holograms, plus Wires and Lifts.

Solution

Robb•2mo ago

I mean when you are playing in the game client and someone joins you (no dedicated server involved) this table (unrelated to the issue) shows the "types" of multiplayer

PiggyChu620OP•2mo ago

Oh, I don't know you can do this, let me try, thank you very much. @Robb (Busy) I fixed it. After I saw the table, I moved the assignment functions to the modsubsystem and marked it SpawnOnClient and it worked, no need for replications or SCS hooks or anything. Now I don't know how that will affect the "big picture", but I see that the dedi server is actually "just a host" and did not share any data with the clients, so I don't think it'll affect anything. Thank you very much for your help.

Robb•2mo ago

glad that worked out! here is the docs page that table is from for future reference: https://docs-dev.ficsit.app/satisfactory-modding/latest/Development/ModLoader/Subsystems.html#_replication_policy

Mod Subsystems :: Satisfactory Modding Documentation

If you’re looking for the subsystems that SML provides by default, check out the Registry page. Subsystems are actors that exist...

PiggyChu620OP•2mo ago

OK, thanks! 😊

PiggyChu620OP•2mo ago

@Robb Turns out that I didn't actually fix it, it's just an "illusion". I checked the logs more carefully this time and noticed that there is

LogNet: Warning: UActorChannel::ProcessBunch: ReadContentBlockPayload failed to find/create object. RepObj: NULL, Channel: 24

before the assignment, I went look it up and found out it means the component is not synced, I can't figure out why, I did mark the component SetIsReplicatedByDefault(true); and replicate every property, even marked the functions Reliable, WithValidation and all that stuff, but somehow it failed to sync with each other, could you share some insight, please?

Robb•2mo ago

hmm, are you getting the desired behavior on the client and server sides despite that message? since it is an actor component, there might be something more you have to do to make it replicate, I have no idea what to check next though

PiggyChu620OP•2mo ago

It's really weird and funny, when I use the replicated actor component, the value is changed but not the visual, still gives me "belt too long" warning but it's actually within the new length limit, and when I use the independent subsystem, the visual is changed but not the value, I can drag the belt infinitely long, but when I confirm it, nothing is built, sometimes even crash the game with "belt too long" error. I end up cheesed it by use them both, one takes care of the actual value and one takes care of the visual. 😅 I know I'm not supposed to do stuff like this, but I can't figure out why and how to fix it, and many people are waiting for it to be fixed, so I have no choice but to cheese it for now. 😫

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Multicast function didn't actually update the property on the client side