Detect player team change

[ShaiHulud]

Just wanted to share something I observed recently while working on a Nexgen plugin. Nexgen (and other mutators that I've peered into) keeps track of player team changes by testing the playerReplicationInfo.team value against a stored team value in a timer event with a short fuse.

If these two numbers diverge, Nexgen issues a playerTeamChanged() call to plugins. In the vast majority of instances this works just fine. But for reasons that would be too long-winded to go into, I needed something that had a direct link back to the line that caused the team change to happen in the first place - in other words, I didn't want additional game ticks to take place before I had a chance to intercept and deal with them.

So poking around, and tracing through the class hierarchy, I eventually found the AddToTeam() function inside of TeamGamePlus (so, obviously, this will only be applicable to TeamGamePlus derived game types).

Near the end of the AddToTeam() function, a call to BroadcastLocalizedMessage() is issued, and this can be intercepted by a mutatorBroadcastLocalizedMessage() function in a mutator to watch for the relevant LocalMessage class, e.g.,

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function bool mutatorBroadcastLocalizedMessage(actor sender, pawn receiver, out class<LocalMessage> message, out optional int switch, out optional playerReplicationInfo relatedPRI_1, out optional playerReplicationInfo relatedPRI_2, out optional object optionalObject)
{
  local teamInfo TI;

  if (message == class'botpack.deathMatchMessage' && sender.isA('CTFGame') && switch == 3)
  {
    TI = teamInfo(optionalObject);
    // TI.teamIndex contains the new team number
    // relatedPRI_1 is the playerReplicationInfo for the player who changed teams
    if (TI != none)
      LOG(relatedPRI_1.playerName $ " SWITCHED TO TEAM " $ TI.teamIndex);
  }

  return true;
}

[EvilGrins]

In my experience, when playing if anyone changes teams a message pops on the screen and states it.

How is this better than that?

[ShaiHulud]

It isn't, it's not intended as a replacement of any kind, I just added the code snippet here for anyone who might be writing a mutator, and who wants a way to detect player team changes in their script.

[Sp0ngeb0b]

Thanks for sharing that hook Shai! Out of curiousity, how do other teamgame gametypes setup that message? Referring to the "sender.isA('CTFGame') && switch == 3" conditions - is above code snippet generally applicable?

[Dennis]

You can also just add the playerReplicationInfo.team check in a function Tick() to detect it just as fast?

[ShaiHulud]

Thanks for sharing that hook Shai! Out of curiousity, how do other teamgame gametypes setup that message? Referring to the "sender.isA('CTFGame') && switch == 3" conditions - is above code snippet generally applicable?

Good question, Sponge, I was being totally single-minded about figuring out a solution for my situation, so I haven't investigated other scenarios so far!

You can also just add the playerReplicationInfo.team check in a function Tick() to detect it just as fast?

Very true, but as I mentioned, in this very particular case I didn't want additional game ticks to occur between the team change and my ability to respond to it, so this technique meant I was able to satisfy that requirement.

[Dennis]

Very true, but as I mentioned, in this very particular case I didn't want additional game ticks to occur between the team change and my ability to respond to it, so this technique meant I was able to satisfy that requirement.

But if you hook a message then you will also be on next tick() as one tick() has to occur before input is processed into message? So we are on the same Tick() regardless what method is used correct?

[sektor2111]

Referring to the "sender.isA('CTFGame') && switch == 3" conditions - is above code snippet generally applicable?

if Sender is Pawn then... I'm really scared...
I don't get if a Sender can be a game-type. Tell me that I'm wrong.

Resuming.
If I want to detect a team change, I think my methods are not really bad. Once again, assign an actor tracking players with vars "OldTeam" "CurrentTeam" working in a SLOW timer NOT TICK (not 80 times/second or such ticks) - we don't have to exhaust resources for something simple. When OldTeam != CurrentTeam this means that player has changed team - here you can increment something "Changes++". If a limit is set, do what is supposed to be done (eat his legs, arms, etc.)

[snowguy]

Thanks for writing about this Shai. Just had occasion to use it and was happy to not have to put additional checks in a tick or timer.

A couple things that might be worth mentioning that I learned when using it. It seems the function is called for each pawn (or is it playerpawn?) on the server so the log would be repeated multiple times depending on the number of players and spectators on the server. I changed the TI check to this to make it only log once:

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if (TI != none && receiver.PlayerReplicationInfo!= none && receiver.PlayerReplicationInfo == relatedPRI_1)

Also, I broke other mutators in the chain that used this function when using the code as is so I changed the 'return true' to the following:

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return Super.MutatorBroadcastLocalizedMessage( Sender, Receiver, Message, Switch, RelatedPRI_1, RelatedPRI_2, OptionalObject );

The mutator I was working with had already registered itself as a message mutator so I'm not sure if that is required for the use of this function or if it had any bearing on my findings listed above. If anyone has more info about this I would like to know.