This document is about: QUANTUM 3
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Motor Dome

Level 4

Overview

The Quantum Motor Dome sample demonstrates an approach on how to build a free-for-all Snake-like sports game for up to 6 players, featuring hands-off host-or-join lobbying, automatic game state progression with a custom-built FSM system, broadphase hit detection, and player customization.

Before You Start

Create a Quantum AppId from the Photon Dashboard and paste it into the AppId in the PhotonServerSettings asset, located in the Unity project under Assets/Resources. Select StartScene from the scenes dropdown and press the play button.

Download

Version Release Date Download
3.0.0 Jun 18, 2024 Motor Dome 3.0.0 Build 399

Highlights

Technical

  • Broadphase Queries for collision handling
  • Custom state machine for game state
  • Custom baked map data using MapDataBakerCallback
  • Player nicknames and player character customization

Gameplay

The core gameplay features include:

  • Full game loop, including pre-game lobby and post-game screen.
  • Spawn protection
  • Randomly Spawned Pickups
  • News feed for gameplay events

Project

Input

The project uses the legacy Unity input system. (gamepad inputs are listed as Xbox buttons)

local input:

  • P key to open the pause menu

quantum input:

  • steer with A and D keys / left and right arrows / left thumbstick X axis
  • boost with W key / up arrow / A button / RB
  • brake with S key / down arrow / B button / LB

Getting Into A Game

Matchmaking: To play an online match, select Matchmaking followed by Start Queue. At this point, the Matchmaker takes over and the Quantum session begins. After a brief waiting period, the LoadSyncSystem will progress to the intro sequence, after which the game will begin. The game state is entirely autonomous, not relying on player input to progress.

Practice Mode: To play a solo match, select practice. The QuantumRunnerLocalDebug in the game scene handles starting up the Quantum session. The intro phase will be bypassed by the LoadSyncSystem.

Matchmaker

Deriving from QuantumCallbacks and implementing IConnectionCallbacks, IMatchmakingCallbacks, IInRoomCallbacks, IOnEventCallback, the Matchmaker class takes care of the flow of connecting to a game and delegating the various callbacks. The main entry point is the static Connect method, which signals back to the caller when the connection state updates.

Game State

The Game State System enables and disables systems which implement any of the game state interfaces. Systems may implement one or many interfaces, and will be enabled while in any of the corresponding game states. Systems which do not implement a game state interface remain untouched by the game state system. When the game state changes, a GameStateChanged event is sent, containing both the old and new game state. The system is designed to be reusable, and can have states changed or added with little effort.

The files relevant to the game state system are:

pre

quantum.code
└ Game
  ├ Game State
  │ ├ gameState.qtn
  │ └ IGameStates.cs
  └ Systems
    └ GameStateSystem.cs

Events

The EventSubscriptions class listens for the majority of events. All "player" events are delegated to the InterfaceManager for handling.

State System:

  • GameStateChanged

Gameplay:

  • PickupCollected
  • PlayerDied
  • PlayerLeadGained
  • PlayerReconnected
  • PlayerScoreChanged

Other:

  • PlayerLeft
  • PlayerDataChanged
  • Shutdown

Events listened to by the ShipView class:

  • PlayerVulnerable
  • PlayerDataChanged

Collisions

Collisions between players leverage Quantum's broadphase queries. Pickups use PhysicsCollider3D and OnTriggerEnter3D for collision detection.

Broadphase: ShipCollisionInjectionSystem.cs - For each ship, a linecast query is added for each segment of the ship's trail. ShipCollisionRetrievalSystem.cs - Evaluates collisions between ships and trails, and differentiates a ship colliding with the end of its own trail for scoring.

Pickups: PickupSystem.cs - Collisions with pickups rely on ships having a PhysicsCollider3D with the callback flag OnDynamicTriggerEnter, and pickups having a PhysicsCollider3D with IsTrigger ticked. These are configured on the entity prototypes, and can be found in Assets/Resources/DB/Quantum Prefabs of the Unity project.

Custom Baked Map Data

This sample utilizes the UserAsset field of the MapData asset to associate additional information with the map. See Map Baking for more information.

Quantum:

  • MapMeta.cs - Stores the position of spawnpoints, and the size and origin of the play space.

Unity:

  • MapDataMeta.cs - A MonoBehaviour which holds information to be baked to the MapMeta asset.
  • CustomMapBaker.cs - Derives from MapDataBakerCallback in order to bake the view-side map data into the Quantum-side MapMeta asset.

Customization

Unity:

  • LocalData.cs - Holds customization data before it has been sent to Quantum.

Quantum:

  • RuntimePlayer.User.cs - Serializes the player's nickname, ship prototype, and selected colors. The view can then access these by retrieving the RuntimePlayer via the frame's GetPlayerData method.

The below snippet shows how a ColorRGBA may be serialized. Note that the alpha is not used, and so does not need to be serialized. Each color then uses only 3 bytes.

C#

partial void SerializeUserData(BitStream stream)
{
    /* ... */
    stream.Serialize(ref primaryColor.R);
    stream.Serialize(ref primaryColor.G);
    stream.Serialize(ref primaryColor.B);
    /* ... */
}
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