Unity粒子系统制作手雷爆炸

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Collisions : MonoBehaviour
{
    public static int GRENADE_AMMO = 0;
    // Start is called before the first frame update
    void Start()
    {
    }
    // Update is called once per frame
    void Update()
    { 
        RaycastHit hit;
        //check if we are collidering
        float rayCastLength = 5;
        Vector3 offset = new Vector3(0,0.5f,0);
        if (Physics.Raycast(transform.position+offset, transform.forward,out hit ,rayCastLength ))
        {
            //...with a door
            if (hit.collider.gameObject.tag == "Door")
            {
                //open the door
                hit.collider.gameObject.GetComponent<Animation>().Play("Door-open");    
            }
        }
        Debug.DrawRay(transform.position + offset, transform.forward, Color.red);
    }
    void OnTriggerEnter(Collider hit)
    {
        if (hit.gameObject.tag == "CrateGrenades")
        {
            Debug.Log("hit");
            //destory the ammo box
            Destroy(hit.gameObject);
            //add ammo to inventory
            GRENADE_AMMO += 200;
            print("YOU NOW HAVE " + GRENADE_AMMO + " GRENADES");
        }
    }
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Shooting : MonoBehaviour
{
    // Start is called before the first frame update
    float  speed = 3;
    Vector3 offset = new Vector3(0, 1.0f, 0f);
    [Tooltip("gp")]
    public GameObject GrenadePrefab;
    void Start()
    {
    }
    // Update is called once per frame
    void Update()
    {
        Screen.lockCursor = true;
        //find out if a fire button is pressed
        if (Input.GetMouseButtonDown(0))
        {
            Debug.Log("shoot");
            if (Collisions.GRENADE_AMMO > 0)
            {
                //create the prefab
                    GameObject grenade = Instantiate(GrenadePrefab, this.transform.localPosition+ offset+ transform.forward, Quaternion.identity);
                //add force to the prefab
                grenade.GetComponent<Rigidbody>().AddForce(transform.forward * 20, ForceMode.Impulse);
                Collisions.GRENADE_AMMO--;
                print("YOU NOW HAVE " + Collisions.GRENADE_AMMO + " GRENADES");
            }
        }
    }
}

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class GrenadeScript:MonoBehaviour
{
    private float creationTime;
    public GameObject explosionPrefab;
    int lifetime = 3;
    // Start is called before the first frame update
    void Start()
    {
    }
    void Awake()
    {
        Debug.Log("count");
        creationTime = Time.time;
    }
    // Update is called once per frame
    void Update()
    {
        if (Time.time > (creationTime + lifetime))
        {
            //Destroy(this.gameObject);
            Instantiate(explosionPrefab, transform.position, Quaternion.identity);
        }
    }
}