How do I randomize the texture brightness with time?

Unity Engine
1

I am trying to simulate a custom after burner effect with a scrolling texture and MK Glow.

This scrolls the texture.

Now how do I make the texture brightness change with time?

using UnityEngine;
using System.Collections;

public class scrolling_texture : MonoBehaviour {
public int materialIndex = 0;
       public float scrollSpeed = 0.5F;
     public Renderer rend;
     void Start() {
         rend = GetComponent<Renderer>();
     }
     void Update() {
         float offset = Time.time * scrollSpeed;
         rend.material.SetTextureOffset("_MainTex", new Vector2(offset, 0));
     }
    
}

3637378--296830--after flicker burner.jpg
3637378--296830--after flicker burner.jpg1273×743 246 KB

2

One trick is to combine sine waves running at different frequencies.

Maybe something like:

float glowRandom = Mathf.Sin(Time.time * 0.57f * myGlowFlickerSpeed) * Mathf.Sin(Time.time * 0.72f * myGlowFlickerSpeed) * Mathf.Sin(Time.time * 1.29f * myGlowFlickerSpeed); // -1 to +1
glowRandom = glowRandom * 0.5f + 0.5f; // 0 - 1
float glowBrightness = glowRandom * myGlowBrightnessMultiplier;
rend.material.SetFloat("GlowPower", glowBrightness);