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Player Controller ​

The Player Controller (APlayerController) refers to a "glue" layer between a human sitting in front of a screen interacting with the game and the game itself.

Something that makes me laugh from an actual page on the Unreal documentation site also explains it:

INFO

A PlayerController is the interface between the Pawn and the human player controlling it. The PlayerController essentially represents the human player's will.

I can't let you do that, Dave...

Anyways:

It is responsible for a multitude of shit that make most of the game just work. At a glance, the Player Controller can handle things like:

  • Input
  • Camera
  • User-interface Elements
  • You name it!

What You Should Know ​

  • The Player Controller exists for every Local Player on a client.
  • Got 4 players playing split-screen? Congratulations, that's four Player Controllers
  • Player Controllers do not replicate from server to client by default (except for the Local Player's Controller)
  • If you have a valid Player Controller, then you definitely have a valid Local Player (ULocalPlayer)

This Thing is Everywhere ​

In general, it's a construct that is shared by many pieces of the game, and as such, a lot of shit knows how to get the Player Controller.

  • AActor has GetOwner() which you can cast: Cast<APlayerController>(GetOwner())
  • You can also use GetInstigatorController() if the actor was spawned by a pawn
  • UUserWidget has GetOwningPlayer()
  • UWorld has GetPlayerControllerIterator(), GetFirstPlayerController(), GetFirstPlayerController()

If you have any object that is World Aware, then you basically have a way to hassle-free retrieve the Player Controller

Client and Server ​

The Player Controller is one of those things you'll pull your hair out trying to reason about because, I don't know, good documentation is hard to come by, I guess.

Here's what I've found out after suffering long enough:

On The Server:

  • Every connected player has a Player Controller
  • Every Player Controller is accessible via GetWorld()->GetPlayerControllerIterator()

On The Client:

  • Has only its own Player Controller, meant to represent the Local Player
  • DOES NOT have Player Controllers for other networked players
  • APlayerState exists instead of a Player Controller for discovering other player's information

Example:

  1. If we have a networked multiplayer match with 4 players:
  • The server has 4 Player Controllers
  • Each client has 1 Player Controller (representing their Local Player)
  1. If we had the same networked multiplayer match with 4 players, but 2 of them were playing split screen on the same client:
  • The server has 4 Player Controllers
  • The client with split-screen has 2 Player Controllers
  • The other two clients playing without split screen each have 1 Player Controller

Authority ​

Listen, I don't know much about this, but I do know that a Player Controller knows when it's local or not. A Player Controller can call IsLocalPlayerController. Which means there are probably things that a client can do or request of its local Player Controller.

If I (need to) figure it out I'll come back here.

Additional Notes ​

  • Player Controllers have one of the longest lifetimes. They persist through Pawns and sometimes level / map transitions.

Painstakingly updated: