VRCycling/Assets/Scripts/TrafficSimulation/CarPool.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Assertions.Must;
using UnityEngine.Serialization;

namespace TrafficSimulation{
    public class CarPool : MonoBehaviour
    {
        public TrafficSystem trafficSystem;
        public static CarPool SharedInstance;
        public List<GameObject> carModels;
        public List<GameObject> pooledCars;
        public int poolSize;
        public bool randomizeRayLength = false;
        public int rayRandomizeRange = 4;
        void Awake() {
            SharedInstance = this;    
            pooledCars = new List<GameObject>();
            GameObject tmpInstance;
            for(int i = 0; i < poolSize; i++){
                tmpInstance = Instantiate(carModels[Random.Range (0, carModels.Count)]);
                VehicleAI vAI = tmpInstance.GetComponent<VehicleAI>();
                if(vAI == null){
                    Debug.Log("Carmodel has no AI. Destorying Instance!");
                    Destroy(tmpInstance);
                    continue;
                }
                vAI.trafficSystem = this.trafficSystem;

                CarSitter carSitter = tmpInstance.GetComponent<CarSitter>();
                if(carSitter != null){
                    carSitter.carPool = this;
                }
                tmpInstance.SetActive(false);
                pooledCars.Add(tmpInstance);
            }
        }

        public GameObject GetCar(){
            foreach(GameObject car in pooledCars){
                if(!car.activeInHierarchy){
                    return car;
                }
            }
            Debug.Log("no car free to use. returning null!");
            return null;
        }
        public GameObject SpawnCar(Transform spawnTranform){
            return SpawnCar(spawnTranform.position, spawnTranform.rotation, null);
        }
        public GameObject SpawnCar(Vector3 spawnPos, Quaternion spawnRot, Transform lookAt)
        {
            GameObject car = this.GetCar();
            if (car == null)
            {
                Debug.Log("No car was available. Spawn aborted");
                return null;
            }
            PrepareCarToSpawn(car, spawnPos, spawnRot, lookAt);
            return car;
        }
        public void DespawnCar(GameObject car){
            car.SetActive(false);
        }

        private void PrepareCarToSpawn(GameObject car,Vector3 position, Quaternion rotation,Transform lookAt)
        {
            //Position + Rotation + Lookat
            car.transform.position = position;
            car.transform.rotation = rotation;
            if(lookAt != null)
            {
                car.transform.LookAt(lookAt);
            }
            
            //Status correction. Necessary when the car was despawned while in intersection
            VehicleAI ai = car.GetComponent<VehicleAI>();
            ai.vehicleStatus = Status.GO;

            //If given, randomize RaycastLength
            if (this.randomizeRayLength)
            {
                float defaultLength = ai.raycastLength;
                ai.raycastLength = Random.Range(defaultLength - this.rayRandomizeRange,
                    defaultLength + rayRandomizeRange);
            }
            
            car.SetActive(true);
        }
    }
}