hatebin

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.AI;

public class CarAIManager : MonoBehaviour
{
    [SerializeField] public float carSpeed = 5f;
    [SerializeField] public float safeDistance = 2f;

public GameObject currentTrafficRoute; // Set of waypoints gameobject along a road
    public GameObject nextTrafficRoute; // The next set of waypoints the car goes to when crossing a signal

[SerializeField] public int currentWaypointNumber;

NavMeshAgent carNavMeshAgent;
    
    void Start() 
    {
        carNavMeshAgent = this.gameObject.GetComponent<NavMeshAgent>();
        carNavMeshAgent.speed = carSpeed; 
    }

// Update is called once per frame
    void Update()
    {
        RaycastHit hit;
        Physics.Raycast(transform.position, transform.right, out hit, safeDistance);
        
        if(hit.transform)
        {
            if(hit.transform.tag == "Car")
                StopCar();
            if(hit.transform.tag == "Waypoint")
                MoveCar();
        }
        else
        {
            MoveCar();
        }
    }

void StopCar()
    {
        carNavMeshAgent.speed = 0;
    }

void MoveCar()
    {
        if(nextTrafficRoute == null)
            carNavMeshAgent.speed = 0;
        else
            carNavMeshAgent.speed = carSpeed;
        if(currentWaypointNumber < (currentTrafficRoute.transform.childCount - 1)) // keeps moving the car forward by assigning destination as next successive waypoint
        {
            if(carNavMeshAgent.speed == 0)
                carNavMeshAgent.speed = carSpeed;            
            carNavMeshAgent.SetDestination(currentTrafficRoute.transform.GetChild(currentWaypointNumber + 1).transform.position); // Sets the successive waypoint as the car NavMesh destination
            float distance = Vector3.Distance(transform.position, currentTrafficRoute.transform.GetChild(currentWaypointNumber + 1).transform.position); // finds distance between car's current location and next waypoint
            if(distance <= 100) 
            {
                currentWaypointNumber += 1; // updates the waypoint number in the same traffic route
            }
        }
        else if(currentWaypointNumber == currentTrafficRoute.transform.childCount - 1) // when the car reaches the last waypoint it needs to change track
        {
            if(carNavMeshAgent.speed == 0)
                carNavMeshAgent.speed = carSpeed;
            if(nextTrafficRoute != null) // unless car reaches the end of the line
            {
                carNavMeshAgent.SetDestination(nextTrafficRoute.transform.position);
                float distance = Vector3.Distance(transform.position, nextTrafficRoute.transform.position); // distance between car's current location and position of the next waypoint
                if(distance <= 1)
                {
                    currentWaypointNumber = 0; // start of next waypoint of next traffic route (new road after signal crossing)
                    currentTrafficRoute = nextTrafficRoute.transform.parent.gameObject; // updates current traffic route
                }
            }
        }
    }
}