Best practices for multiplayer multi crew vehicles.

Questions & Answers
1

I’ve been looking around for some advice on how to implement multi-crew vehicles in multiplayer within Unity. Basically vehicles that exist as their own entity and players can hop in and out of positions on the vehicle to drive/shoot/etc. The advice I’ve found so far is very thin on the ground, vague, very outdated or refers to something in the assetstore ( that may or may not still exist ).

I’ve run pretty solidly up against the limits of my understanding of Unity multiplayer.

I’ve put together a reasonably functional implementation in singleplayer but I have no idea how to convert that into something that works within the constraints of multiplayer. For example, this is the current setup that I have:

Player(PlayerControllerScript)
Vehicle(VehicleControllerScript)
    Driver(DriverScript)(TriggerCollider)
    Gunner(GunnerScript)(TriggerCollider)

When the player hits a key when inside the trigger area of the driver/gunner the Player object becomes a child of the Driver/Gunner and is disabled, the driver script then takes over processing input from the player.

Vehicle(VehicleControllerScript)
    Driver(DriverScript)(TriggerCollider)
             Player(PlayerControllerScript)
    Gunner(GunnerScript)(TriggerCollider)

This works great in singleplayer but I have no idea how to pass input from the client to the server to tell it to move the player around. Am I at all on the right track or is there a much easier way of implementing this sort of thing?

Your input is much appreciated.

2

Sounds like you are on the right track. Not sure about the high level API, but these are some steps I would generally use for writing a low level protocol.

  • Player 1 parents their controller object to the vehicle object in their scene

  • Server tells everyone to parent the player driving to the vehicle in their scene
    +(Now in everyone’s instance of the game, player 1 is parented to the vehicle object)

  • The player driving now uses vehicle controls – just like an offline game – which moves the vehicle in their scene.

  • The person driving keep sending their position to the server as normal

  • The server should know that player X is now driving the vehicle – they should take that players position and relay it to the other clients as the vehicles position instead.

  • If you had other people join in they would parent the same way to the vehicle object.

  • But their movement would no longer be transmitted (except maybe rotations), since their character is receiving their movement as a child of the vehicle object.

  • Basically, get all the people parented to the vehicle object, and then the server is treating any positions from the person driving as the vehicles position.