Integration: Mirror Networking

Mirror is a free, open-source networking library for Unity. RCCP provides an integration package that enables multiplayer vehicle synchronization using Mirror's networking framework. This guide covers installation, setup, and usage.

Overview

The RCCP Mirror integration follows the same design philosophy as the Photon integration: the vehicle owner sends its state (inputs, drivetrain, lights, transform) to all other clients, and remote clients apply that state with interpolation. Mirror uses a server-authoritative or host model, where one player acts as both server and client (host mode) or a dedicated server relays data.

Mirror is a suitable choice when you want:

Free, open-source networking with no per-CCU costs.
Server-authoritative game logic.
LAN or self-hosted dedicated server support.
Full control over the network transport layer.

Prerequisites

Mirror installed in your project. Download it from the Unity Asset Store (free).
Realistic Car Controller Pro installed and working with at least one vehicle.

Installing

Step 1: Import Mirror

If Mirror is not yet in your project, import it from the Asset Store. After import, the MIRROR scripting symbol is added automatically by Mirror.

Step 2: Import the RCCP Integration Package

Open the RCCP Welcome Window: Tools > BoneCracker Games > Realistic Car Controller Pro > Welcome Window.
Navigate to the Addons tab.
Under Mirror, click Import Mirror Integration.
Unity imports RCCP_MirrorIntegration.unitypackage from Addons/Installers/.
Wait for Unity to recompile.

The integration files are installed to:

Assets/Realistic Car Controller Pro/Addons/Installed/Mirror/

Step 3: Verify Scripting Symbols

After import, the RCCP_MIRROR scripting symbol is added automatically by RCCP_AddonDefineManager. Both MIRROR (from Mirror) and RCCP_MIRROR (from the integration) must be present.

Scripting Symbols

Symbol	Source	Required
`MIRROR`	Mirror package (automatic)	Yes
`RCCP_MIRROR`	RCCP Mirror integration (automatic via `RCCP_AddonDefineManager`)	Yes

Setting Up a Networked Vehicle

Step 1: Start with a Working RCCP Vehicle

Ensure your vehicle works correctly in single-player before adding networking. See Vehicle Setup.

Step 2: Add NetworkIdentity

Select your vehicle prefab.
Add Component: NetworkIdentity.
This is required by Mirror for all networked objects.

Step 3: Add the RCCP Mirror Sync Component

Add the RCCP Mirror synchronization component (provided in the integration package) to your vehicle.
This component handles serialization of vehicle state across the network, similar to RCCP_PhotonSync in the Photon integration.

Step 4: Register as a Spawnable Prefab

Open your scene's NetworkManager component.
In the Registered Spawnable Prefabs list, add your RCCP vehicle prefab.
This allows Mirror to instantiate the vehicle on remote clients.

Step 5: Spawn and Register

On the server or host, spawn the vehicle using Mirror's API:

GameObject vehicleObj = Instantiate(vehiclePrefab, spawnPosition, spawnRotation);
NetworkServer.Spawn(vehicleObj, connectionToClient);

RCCP_CarController vehicle = vehicleObj.GetComponent<RCCP_CarController>();
RCCP.RegisterPlayerVehicle(vehicle);
RCCP.SetControl(vehicle, true);

On each client, after the vehicle is spawned, check isLocalPlayer or isOwned to determine whether to enable local input or apply remote synchronization.

Vehicle Synchronization

The RCCP Mirror sync component follows the same pattern as the Photon sync:

Owner (Local Player)

Inputs are processed locally by the RCCP drivetrain.
Vehicle state is sent to the server (or directly to clients in host mode).
No input overrides are applied.

Remote (Other Players)

Received state is applied via interpolation.
Input and drivetrain modules are overridden with the received network state.
Position and rotation are interpolated using Rigidbody.MovePosition() and Rigidbody.MoveRotation().

Synchronized Data

The integration synchronizes the same data categories as the Photon integration:

Category	Fields
Inputs	throttle, brake, steer, handbrake, NOS boost, clutch
Engine	RPM, starting flag, running flag
Gearbox	current gear, gear input, gear state, shifting flag
Differential	left and right output for each differential
Lights	low beam, high beam, left indicator, right indicator, hazards
Wheels	RPM for each wheel collider
Transform	position, rotation, linear velocity, angular velocity

Authority Model

Mirror supports two authority models. The RCCP integration can work with either:

Server-Authoritative (Recommended)

All vehicle state is validated by the server.
Clients send input commands to the server.
The server applies inputs, simulates physics, and broadcasts the result.
Provides better cheat protection.

Client-Authoritative

The owning client simulates physics locally and sends results to the server.
The server trusts the client's state and relays it to other clients.
Lower latency for the owning player but more vulnerable to cheating.

To configure authority, use Mirror's [ClientAuthority] attribute on sync variables or use [Command] methods for server-authoritative input processing.

Network Manager Setup

A typical Mirror setup for RCCP requires:

NetworkManager -- Add to a persistent GameObject in your starting scene. Configure: - Network Address: localhost for testing, or a server IP for production. - Transport: Choose KCP (recommended), Telepathy, or another Mirror transport. - Player Prefab: Optionally set to an RCCP vehicle, or use a lobby system. - Registered Spawnable Prefabs: Add all RCCP vehicle prefabs that can be spawned.
NetworkManagerHUD (optional) -- Add alongside NetworkManager for quick testing. Provides Host, Client, and Server buttons.

Common Issues

Remote vehicles desync or jitter

Check the sync interval. A higher sync rate produces smoother results but more bandwidth.
Ensure interpolation is enabled on the sync component.
Check server tick rate. Mirror's default tick rate may need tuning for vehicle physics.

Authority errors ("not the owner")

Only the object owner (or server) can modify sync variables.
Check isLocalPlayer or isOwned before applying inputs.
For enter-exit scenarios, transfer authority using NetworkIdentity.AssignClientAuthority().

Vehicle spawns but does not respond to input

After spawning, verify that the local client has authority over the vehicle.
Call RCCP.RegisterPlayerVehicle() and RCCP.SetControl(vehicle, true) on the local client.

Compile errors after import

Ensure both MIRROR and RCCP_MIRROR scripting symbols are defined.
Verify that Mirror is fully imported (check for Mirror namespace availability).

High bandwidth usage

Reduce the sync rate in the Mirror sync component settings.
Consider using unreliable channels for transform data (position, rotation, velocity).

Removing the Integration

Delete the folder: Assets/Realistic Car Controller Pro/Addons/Installed/Mirror/.
Remove the RCCP_MIRROR scripting symbol from Edit > Project Settings > Player > Scripting Define Symbols (or let RCCP_AddonDefineManager handle it automatically).
Wait for Unity to recompile.

Comparison: Mirror vs. Photon

Feature	Mirror	Photon PUN 2
Cost	Free, open-source	Free tier (20 CCU), paid tiers for more
Hosting	Self-hosted or dedicated server	Photon Cloud (managed)
Authority	Server-authoritative by default	Owner-authoritative (client sends state)
Transport	Pluggable (KCP, Telepathy, Steam, etc.)	Photon proprietary
LAN Support	Yes, built-in	Limited (Photon Cloud only in free tier)
Ease of Setup	Moderate (requires server management)	Easy (cloud-hosted, just need App ID)
Scalability	Depends on server hardware	Scales via Photon Cloud pricing tiers