AI System

01Quick Start

1. Bake a NavMesh on your road: install the AI Navigation package (Window → Package Manager), add a NavMesh Surface component to your level, and click Bake. The AI steers along NavMesh paths, so this step is required.
2. Tools → BoneCracker Games → Realistic Car Controller → AI → Add Waypoints Container To Scene.
3. With the new Waypoints Container selected, Shift + Left Click on the road in the Scene view to place waypoints in driving order. The road needs a collider.
4. Select an RCC vehicle and choose Tools → BoneCracker Games → Realistic Car Controller → AI → Add AI Controller To Vehicle. Or drag in Prefabs/Vehicles/Skyline (AI Chaser).prefab, which already has the AI controller.
5. Press Play. The car drives the waypoints in a loop.

The RCC_City and RCC_City_AIO demo scenes contain a working setup (baked NavMesh, waypoints and an AI car).

02How It Works

Figure 01Open full size ↗

• In Awake, the AI creates a child GameObject named Navigator with a NavMeshAgent. The agent computes the path to the current destination; the AI turns that into steering.
• On enable, the AI calls SetExternalControl(true) on the vehicle, so the vehicle ignores player input. On disable it calls SetExternalControl(false).
• Every physics step the AI writes throttle, brake, steer and handbrake directly to the vehicle. It does not use OverrideInputs.
• The AI only runs while the vehicle's canControl is on. A vehicle with control disabled does not drive.
• Above 30 km/h, the AI lifts off the throttle and brakes in proportion to how hard it is steering.
• Stuck recovery (fixed values, not adjustable): below 5 km/h for 2 seconds, the AI reverses. It drives forward again after 4 seconds or once it reaches 25 km/h.

Figure 02Open full size ↗

03Navigation Modes

Set with Navigation Mode on the AI controller.

Figure 03Open full size ↗

In Chase Target and Follow Target, the AI searches for targets about once per second, within Detector Radius, by checking the tag of each collider's root GameObject. With no target found, it stops with the handbrake on.

Important: RCC's vehicle prefabs are Untagged. Chase Target and Follow Target find nothing until you tag the player vehicle's root GameObject with the Target Tag (default Player).

04AI Controller Fields

The inspector groups fields into foldouts. Defaults are the values of a freshly added component.

Figure 04Open full size ↗

The Skyline (AI Chaser) prefab ships with Raycast Length 20, Stop Lap Index 2 and Stop Follow Distance 50. All other values match the table.

Figure 05Open full size ↗

Runtime read-outs (set by the AI, for debugging): Current Obstacle, the Vehicle Input (Runtime) foldout (Steer / Throttle / Brake / Handbrake Input), Current Lap, Total Waypoints Passed, Ignore Waypoint Now (on while obstacle rays override waypoint steering), and the Targets & Brake Zones foldout (Targets In Zone, Brake Zones, Chase Target, Brake Zone Target). The AI overwrites Chase Target each time it searches, so assigning it by hand has no lasting effect.

05Waypoints

Waypoints are child GameObjects of the Waypoints Container, each with an RCC_Waypoint component.

• Add: select the container, then Shift + Left Click on a collider in the Scene view. Each click adds a waypoint at the hit point (undoable).
• Order: the AI follows the children in Hierarchy order. Reorder the children to change the route.
• Plain children: any child without RCC_Waypoint gets one when the container's inspector is shown.
• Delete: the container's Delete Waypoints button removes all waypoints (undoable).
• Gizmos: each waypoint shows a sphere and its radius; green lines connect them, including a closing line from the last waypoint to the first.

Figure 06Open full size ↗

Figure 07Open full size ↗

Use lower Target Speed values on waypoints before corners.

Figure 08Open full size ↗

06Brake Zones

A brake zone makes AI cars brake hard when they are near a point and too fast.

1. Tools → BoneCracker Games → Realistic Car Controller → AI → Add BrakeZones Container To Scene (one per scene; a second one is refused).
2. With the Brake Zones Container selected, Shift + Left Click on the road to place a zone. Each zone gets RCC_AIBrakeZone, a 1 × 1 × 1 trigger BoxCollider and the Ignore Raycast layer.
3. Set the zone's fields:

Figure 09Open full size ↗

• The zone is a sphere of radius Distance. The box collider only lets the AI find the zone and draws the gizmo. Resizing it does not change the zone.
• Only the closest zone within Detector Radius counts. Inside it, above Target Speed, the AI releases the throttle and brakes fully.
• Brake zones work in all three navigation modes.
• Delete Brake Zones on the container removes all zones (undoable).

07Spawning an AI Car from Code

Use a prefab that already has RCC_AICarController (for example Skyline (AI Chaser)). Pass isControllable: true, because the AI does nothing while the vehicle cannot be controlled. Pass registerAsPlayerVehicle: false so the camera and player stay on the player's car.

using UnityEngine;

public class SpawnAICar : MonoBehaviour {

    public RCC_CarControllerV4 aiVehiclePrefab;     // Prefab with RCC_AICarController.
    public RCC_AIWaypointsContainer waypoints;      // Route to follow.
    public Transform spawnPoint;

    private void Start() {

        RCC_CarControllerV4 vehicle = RCC.SpawnRCC(aiVehiclePrefab, spawnPoint.position, spawnPoint.rotation, false, true, true);

        RCC_AICarController ai = vehicle.GetComponent<RCC_AICarController>();
        ai.navigationMode = RCC_AICarController.NavigationMode.FollowWaypoints;
        ai.waypointsContainer = waypoints;

    }

}

To stop an AI car and hold it in place, disable the AI and remove control:

ai.enabled = false;                      // Hands the vehicle back from the AI.
RCC.SetControl(ai.CarController, false); // No input: throttle 0, handbrake on.

Disable the AI first. If you only remove control, the vehicle keeps the AI's last inputs.

08AI and the Player Vehicle

• AI vehicles are never registered as the player vehicle automatically. Register Last Spawned Vehicle As Player Vehicle on the Scene Manager ignores them.
• To point the camera at an AI car, call RCC.RegisterPlayerVehicle(aiVehicle). The AI keeps driving.

Changed in V6: registering a new player vehicle takes control away from the previous one, but vehicles driven by an external controller (AI, replay, network) are never released. Registering an AI car does not take control from the current player car, and registering a player car does not stop an AI car.

• A plain OverrideInputs(inputs) does not take over from the AI. See Overriding Inputs for the precedence rules.
• RCC_Events.OnRCCAISpawned / OnRCCAIDestroyed fire when an AI controller is enabled or disabled. See Events System.

09See Also

• Overriding Inputs
• Events System
• Scripting API
• Demo Scenes
• Troubleshooting