Why here StartCorotine() is necessary - unity3d

Question

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class FirePistol : MonoBehaviour {
public GameObject TheGun;
public GameObject MuzzleFlash;
public AudioSource GunFire;
public bool IsFiring = false;
void Update () {
if (Input.GetButtonDown("Fire1"))
{
if (IsFiring == false)
{
StartCoroutine(FiringPistol());
}
}
}
IEnumerator FiringPistol ()
{
IsFiring = true;
TheGun.GetComponent<Animation>().Play("PistolShot");
MuzzleFlash.SetActive(true);
MuzzleFlash.GetComponent<Animation>().Play("MuzzleAnim");
GunFire.Play();
yield return new WaitForSeconds(0.5f);
IsFiring = false;
}
}
I am writing a gun mechanic And
I wonder why we need
yield return new WaitForSeconds(0.5f); .What is the difference without this command .It's really unnecessary to write this code coz the time is short .Afterall , will it be an error like scene crash after i deleting this code ?Any help is greatly appreciated !

Answer 1

In general: Every method returning IEnumerator has to contain at least one yield statement. In Unity you have to use StartCoroutine to run an IEnumerator as Coroutine.
In your specific case: So you can delay your code by 0.5 seconds!
It is short but 0.5 is about 30 frames!
Someone using e.g. something like AutoClicker could jam the fire key each frame so he would cause significantly more damage then someone playing "normal" (due to physical limitations of your keyboard and finger ;) )
You are just avoiding that and limit down firing to a maximum of 2x per second.
In general - as usual - there are multiple ways to achieve that and you could go without Coroutines entirely but it makes coding so much cleaner and easier to maintain then doing everything in Update!
As some alternative examples for simple delays as here you could also either do a simple timer in Update
private float timer;
void Update ()
{
if(timer > 0)
{
// reduce the timer by time passed since last frame
timer -= Time.deltaTime;
}
else
{
if(Input.GetButtonDown("Fire1"))
{
FiringPistol();
timer = 0.5f;
}
}
}
void FiringPistol()
{
TheGun.GetComponent<Animation>().Play("PistolShot");
MuzzleFlash.SetActive(true);
MuzzleFlash.GetComponent<Animation>().Play("MuzzleAnim");
GunFire.Play();
}
or you can also use Invoke with a given delay.
bool canFire;
void Update ()
{
if (Input.GetButtonDown("Fire1") && canFire)
{
FiringPistol();
}
}
void FiringPistol()
{
TheGun.GetComponent<Animation>().Play("PistolShot");
MuzzleFlash.SetActive(true);
MuzzleFlash.GetComponent<Animation>().Play("MuzzleAnim");
GunFire.Play();
Invoke(nameof(AfterCooldown), 0.5f);
}
void AfterCooldown()
{
canFire = true;
}
In general btw you should store the Animation references to not use GetComponent over and over again:
// if possible already reference these via the Inspector
[SerializeField] private Animation theGunAnimation;
[SerializeField] private Animation muzzleFlashAnimation;
private void Awake()
{
// as fallback get them on runtime
// since this is a fallback and in best case you already referenced these via the Inspector
// we can save a bit of resources and use GetComponent
// only in the case the fields are not already set
// otherwise we can skip using GetComponent as we already have a reference
if(!theGunAnimation) theGunAnimation = TheGun.GetComponent<Animation>();
if(!muzzleFlashAnimation) muzzleFlashAnimation = MuzzleFlash.GetComponent<Animation>();
}
then later you reuse them
theGunAnimation.Play("PistolShot");
MuzzleFlash.SetActive(true);
muzzleFlashAnimation.Play("MuzzleAnim");
GunFire.Play();