HOW TO CREATE A SIMPLE TRAFFIC CAR SYSTEM IN UNITY

using System.Collections.Generic;
using UnityEngine;

public class TrafficCarAI : MonoBehaviour
{
    [Header("Speed & Navigation")]
    [SerializeField] private float topSpeed = 12f; // m/s
    [SerializeField] private float turnSpeed = 90f; // deg/s
    [SerializeField] private float reachThreshold = 1.5f;

    [Header("Obstacle Detection")]
    [SerializeField] private float sensorLength = 8f;
    [SerializeField] private LayerMask obstacleLayer;

    [Header("Waypoints")]
    [SerializeField] private List<Transform> waypoints = new List<Transform>();
    private int currentWaypointIndex = 0;

    private float currentSpeed;

    private void Start()
    {
        currentSpeed = topSpeed;
    }

    private void Update()
    {
        if (waypoints == null || waypoints.Count == 0) return;

        bool isBlocked = CheckForwardObstacle();
        
        // Smoothly accelerate or brake
        float targetSpeed = isBlocked ? 0f : topSpeed;
        currentSpeed = Mathf.MoveTowards(currentSpeed, targetSpeed, (isBlocked ? 25f : 8f) * Time.deltaTime);

        NavigateTowardsWaypoint();
    }

    private void NavigateTowardsWaypoint()
    {
        Transform targetNode = waypoints[currentWaypointIndex];
        Vector3 targetPosition = new Vector3(targetNode.position.x, transform.position.y, targetNode.position.z);
        Vector3 direction = (targetPosition - transform.position).normalized;

        if (direction != Vector3.zero)
        {
            // Rotate smoothly towards waypoint
            Quaternion targetRotation = Quaternion.LookRotation(direction);
            transform.rotation = Quaternion.RotateTowards(transform.rotation, targetRotation, turnSpeed * Time.deltaTime);
        }

        // Move forward
        transform.position += transform.forward * (currentSpeed * Time.deltaTime);

        // Check if reached current waypoint
        if (Vector3.Distance(transform.position, targetPosition) < reachThreshold)
        {
            currentWaypointIndex = (currentWaypointIndex + 1) % waypoints.Count;
        }
    }

    private bool CheckForwardObstacle()
    {
        Vector3 rayOrigin = transform.position + Vector3.up * 0.5f;
        return Physics.Raycast(rayOrigin, transform.forward, sensorLength, obstacleLayer);
    }

    public void SetPath(List<Transform> pathNodes)
    {
        waypoints = pathNodes;
        currentWaypointIndex = 0;
    }
}