How the System Works

01Component Map

Figure 01Open full size ↗

Classes that do not inherit RCC_Core: RCC_TruckTrailer (a plain MonoBehaviour), RCC_Events, RCC_CheckUp and RCC_GetBounds (plain classes), and the data classes RCC_Inputs and RCC_Damage (serializable classes, not components — RCC_Damage is the damage field on the vehicle).

All paths are relative to Assets/RealisticCarControllerV4/.

02A Frame in the Life of a Vehicle

Figure 02Open full size ↗

Every frame (Update)

1. RCC_InputManager reads the Input System (or the mobile buttons, when Mobile Controller is enabled) into its inputs (an RCC_Inputs).
2. RCC_CarControllerV4 copies those inputs into its own throttleInput, brakeInput, steerInput, handbrakeInput, etc., applying steering sensitivity and assists. It also updates engine audio and damage.
3. RCC_WheelCollider moves each wheel mesh to match its collider.
4. RCC_Light, RCC_Exhaust and the dashboard UI react to the vehicle's current values (brake, RPM, speed, gear…).

Every physics step (FixedUpdate)

1. AI (RCC_AICarController) and replay (RCC_Recorder) write their inputs straight into the vehicle.
2. RCC_CarControllerV4 runs the engine, steering and gearbox, then pushes motor torque, brake torque and steer angle into each RCC_WheelCollider. Assists (ABS, ESP, TCS, steering / traction helpers), anti-roll bars and downforce run here.
3. RCC_WheelCollider finds the surface under the wheel, sets the friction curves, and handles skidmarks, wheel particles and wheel audio.
4. Unity's physics moves the Rigidbody.

After that (LateUpdate) — RCC_Camera follows the vehicle.

Friction starts from the active behavior preset (when the global preset is on and the vehicle doesn't ignore it) and is scaled by the ground material. See Behavior Presets, Ground Physics and How WheelColliders Work.

Script execution order

RCC sets this automatically on import (Editor/InitLoad/RCC_ScriptExecutionOrderManager.cs). Don't change it by hand.

03Player Vehicle Registration

The Scene Manager (RCC_SceneManager) tracks the player vehicle (activePlayerVehicle), the player camera and all vehicles in the scene. Add it with Tools → BoneCracker Games → Realistic Car Controller → Create → Managers → Add RCC Scene Manager; if you don't, it is created automatically when first needed.

A vehicle becomes the player vehicle in one of two ways:

• Automatically. Every vehicle that is not AI-controlled announces itself when it spawns. With Register Last Spawned Vehicle As Player Vehicle on (the default), the Scene Manager registers it. The last one to spawn wins.
• From code. RCC.RegisterPlayerVehicle(vehicle), with overloads that also set controllability and engine state. RCC.DeRegisterPlayerVehicle() clears it.

Registering points the camera at the vehicle.

Figure 03Open full size ↗

Changed in V6: registering a new player vehicle takes player control away from the previous one, so only one car answers your input. A previous vehicle driven by AI, replay, network or override inputs is left alone, and registering an AI car (for example to watch it) releases nothing.

04Where Settings Come From

Figure 04Open full size ↗

In Play mode, RCC_Settings.Instance returns a copy of the asset. Runtime changes (for example switching presets with RCC.SetBehavior) are gone when you stop playing; edit the asset outside Play mode to keep a change.

Changed in V6: the Play-mode copy is never used after you leave Play mode, so edits you make to RCC Settings in edit mode always reach the asset.

The five behavior presets (Balanced, Racing, Drift, Semi Arcade, Fun) live in RCC_Settings, and the global preset ships off. Details: Behavior Presets and RCC Settings.

05Extension Points

Extend RCC from your own scripts instead of editing RCC's — your changes then survive updates.

Things to know:

• AI does not use OverrideInputs. RCC_AICarController calls SetExternalControl(true) on its vehicle and writes the inputs directly. An externally controlled vehicle ignores player input and input events. See AI System.
• Input events fire on the key press, for everyone. For example RCC_Events.OnGearShiftUp fires when the gear-up input is pressed, not when a gear change happens; each vehicle decides whether to act on it.
• OnRCCPlayerSpawned fires for every non-AI vehicle when it spawns, not only for the registered player vehicle.

Example — log every player-vehicle collision:

using UnityEngine;

public class CollisionLogger : MonoBehaviour {

    private void OnEnable() {
        RCC_Events.OnRCCPlayerCollision += OnVehicleCollision;
    }

    private void OnDisable() {
        RCC_Events.OnRCCPlayerCollision -= OnVehicleCollision;
    }

    private void OnVehicleCollision(RCC_CarControllerV4 vehicle, Collision collision) {
        Debug.Log(vehicle.name + " hit " + collision.gameObject.name);
    }

}

Other systems: Cameras, Lights, Input System, Mobile Setup, Damage, Customization, Render Pipelines.

06See Also

• Vehicle Inspector Reference
• Scripting API
• Events System
• How to Override Inputs
• Scripts Reference