Unity simple & fast light flicker script

LightFlickerEffect.cs

using UnityEngine;
using System.Collections.Generic;

// Written by Steve Streeting 2017
// License: CC0 Public Domain http://creativecommons.org/publicdomain/zero/1.0/

/// <summary>
/// Component which will flicker a linked light while active by changing its
/// intensity between the min and max values given. The flickering can be
/// sharp or smoothed depending on the value of the smoothing parameter.
///
/// Just activate / deactivate this component as usual to pause / resume flicker
/// </summary>
public class LightFlickerEffect : MonoBehaviour {
    [Tooltip("External light to flicker; you can leave this null if you attach script to a light")]
    public new Light light;
    [Tooltip("Minimum random light intensity")]
    public float minIntensity = 0f;
    [Tooltip("Maximum random light intensity")]
    public float maxIntensity = 1f;
    [Tooltip("How much to smooth out the randomness; lower values = sparks, higher = lantern")]
    [Range(1, 50)]
    public int smoothing = 5;

    // Continuous average calculation via FIFO queue
    // Saves us iterating every time we update, we just change by the delta
    Queue<float> smoothQueue;
    float lastSum = 0;


    /// <summary>
    /// Reset the randomness and start again. You usually don't need to call
    /// this, deactivating/reactivating is usually fine but if you want a strict
    /// restart you can do.
    /// </summary>
    public void Reset() {
        smoothQueue.Clear();
        lastSum = 0;
    }

    void Start() {
         smoothQueue = new Queue<float>(smoothing);
         // External or internal light?
         if (light == null) {
            light = GetComponent<Light>();
         }
    }

    void Update() {
        if (light == null)
            return;

        // pop off an item if too big
        while (smoothQueue.Count >= smoothing) {
            lastSum -= smoothQueue.Dequeue();
        }

        // Generate random new item, calculate new average
        float newVal = Random.Range(minIntensity, maxIntensity);
        smoothQueue.Enqueue(newVal);
        lastSum += newVal;

        // Calculate new smoothed average
        light.intensity = lastSum / (float)smoothQueue.Count;
    }

}

Tbh I am not sure what you are asking. What FX are you looking for? Candle? Fire? Explosion? Flickering light in a hospital for a creepy effect? From: Arthur Marquis<mailto:arthur.marquis@live.com> Sent: Sunday, April 26, 2020 1:55 PM To: sinbad<mailto:sinbad@noreply.github.com>; sinbad<mailto:reply@reply.github.com> Cc: Comment<mailto:comment@noreply.github.com> Subject: Re: sinbad/LightFlickerEffect.cs Create a min max for emission then create a random math function to check every frame for a new value and apply it From: Pourya <notifications@github.com> Sent: Sunday, April 26, 2020 1:41:51 PM To: sinbad <sinbad@noreply.github.com> Cc: arthurmarquis <arthur.marquis@live.com>; Comment <comment@noreply.github.com> Subject: Re: sinbad/LightFlickerEffect.cs @pourya0111 commented on this gist. Hello How to add a emision value with independent min max intensity but the same flicker amount? I mean light and a emission source (for example the lamp source itself in 3d world) — You are receiving this because you commented. Reply to this email directly, view it on GitHub<https://gist.github.com/4a9ded6b00cf6063c36a4837b15df969#gistcomment-3270785>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AJN46HJYMSUHSWWQFFQJ7K3ROSMA7ANCNFSM4HOAC7KA>.

Just think of a parking sign that will flicker (maybe emission?) like the light

While this does work, it completely tanks performance changing the lighting on every frame, especially if several are used.

This is awesome! Thank you so much :) It's perfect to apply to other things beyond just light.luminence too

Thank you!

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

public class FlickerLight : MonoBehaviour
{
	Light myLight;

	float maxIntensity = 80.0f;
	float minIntensity = 20.0f;

	void Start()
	{
		myLight = GetComponent<Light>();
		StartCoroutine(Flicker());
	}

	IEnumerator Flicker()
	{

		float t = 0.0f;
		float duration = Random.Range(0.06f, 0.3f);
		float currIntensity = myLight.intensity;
		float targetIntensity = (currIntensity > 50.0f) ? minIntensity : maxIntensity;
		float variation = Random.Range(-20.0f, 20.0f);
		targetIntensity += variation;

		while (t < duration)
                {
			myLight.intensity = Mathf.Lerp(currIntensity, targetIntensity, t / duration);
			t += Time.deltaTime;
			yield return null;
                }

		StartCoroutine(Flicker());
	}
}

@Kiranix regarding your code... well... where do i began...
Using looped enumerators? Well... i mean, i can live with that (we all did this at some point) but its generally not good idea to have core update functionality in coroutines. Why not use update loop? Especially when you are relying on counting wait duration for your functionality?
But whats really problematic here is this code constant magic numbers. I mean... why? At least expose it for editor...
Also: what kind of scene are you using? Minimal light intensity 20? Little bit high dont you think?
But mainly: using time delta in coroutine? This is really not great idea. Like... really REALLY bad idea

It's not that bad. It's straightforward and gives an idea on a dissipating light. It does cause some garbage. Time.deltaTime is not a big deal in his use because he is yield return null, which is equal to waiting for the next Update() call.
There's no reason to hate on it so much??

Hey @stadoblech, thanks a lot for your feedback, I'll take all that into account for future scripting.

About the magic numbers, it was a short quick script, so it was just making it simple to read first sight, I usually prefer that.

About the lighting intensity, I adjusted it for my scene to look as I wanted, that's also why the Magic numbers, just change them according to your scene/pipeline, expose in editor, etc.

And regarding the delta time in coroutine, I would like you to further explain why is that a really bad idea, cause I've used that a lot and I'm really interested on knowing why is that bad. How would you increment the timer "t" inside the while of a coroutine?

Thanks!

I diсided do like this.

 public class FlickeringLight : MonoBehaviour
    {
        [Header("References")]
        [Tooltip("Light Source")]
        [SerializeField] private Light _light;
        [Tooltip("Emission renderer")]
        [SerializeField] private Renderer _renderer;
        [Tooltip("Material index if mesh have more then 1 material")]
        [SerializeField] private int _materialIndex = 0;
        [Space(3f)]
        [Header("Options")]
        [Tooltip("How much to smooth out the randomness; lower values = sparks, higher = lantern")]
        [Range(1, 50)]
        [SerializeField] private int _smoothing = 5;
        [Range(0, 50)]
        [Tooltip("Delay between iterations")]
        [SerializeField] private int _delay = 5;
        [Tooltip("Duration of iterations")]
        [SerializeField] private float _duration = 5;
        
        
        private float _maxIntensity;
        private float _minIntensity = 0;
        private Queue<float> _smoothQueue;
        private float _lastSum = 0;
        private float _colorIntensity;
        private Color _color;
        private float _factor;
        private Coroutine _flickCoroutine;
        private WaitForSeconds _seconds;
        public void Reset()
        {
            StopCoroutine(_flickCoroutine);
            _smoothQueue.Clear();
            _lastSum = 0;
        }
        private void Start()
        {
            _seconds = new WaitForSeconds(_delay);
            _color = _renderer.materials[_materialIndex].GetColor("_EmissionColor");
            _colorIntensity = (_color.r + _color.g + _color.b) / 3f;
            _maxIntensity = _light.intensity;
            _smoothQueue = new Queue<float>(_smoothing);
            _flickCoroutine = StartCoroutine(Flick());
        }

        private void DoFlick()
        {
            if (_light == null)
                return;

            // pop off an item if too big
            while (_smoothQueue.Count >= _smoothing)
            {
                _lastSum -= _smoothQueue.Dequeue();
            }

            // Generate random new item, calculate new average
            float newVal = Random.Range(_minIntensity, _maxIntensity);
            _smoothQueue.Enqueue(newVal);
            _lastSum += newVal;

            // Calculate new smoothed average
            _light.intensity = _lastSum / (float)_smoothQueue.Count;
            _factor = _light.intensity / _colorIntensity;
            _renderer.sharedMaterials[_materialIndex].SetColor("_EmissionColor",new Color(_color.r*_factor,_color.g*_factor,_color.b*_factor));
        }

        private IEnumerator Flick()
        {
            float t = 0.0f;
            yield return _seconds;
            while (t<_duration)
            {
                DoFlick();
                t += Time.deltaTime;
                yield return null;
            }
            _flickCoroutine  = StartCoroutine(Flick());
        }

Movie.003-1.mp4

Forked for 2D URP :)