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Tutorial: Particle Effects

In this tutorial, we will have a brief look at the particle system in Unity. The particle system is a very powerful tool that can be used to configure and create a wide variety of effects that can add a lot of polish to your game. In this tutorial, we will be looking at how we can manipulate the particle system to create a simple explosion effect that we can use when an enemy dies.

The Explosion Effect​

Let's start by creating a new gameobject called ExplosionVFX and add a Particle System component to it. By default, it'll spawn white circular particles that will fade out over time in a conical shape. Now we need to analyze and think about how we want to achieve the explosion effect.

  • We want the particles to be orange/red
  • We want the spawn shape to be a sphere (so that it looks like the particles are coming from a single point of origin)
  • We want the particles to be bigger

We can change the color of the particles by changing the Start Color property to something orange-ish or switching it to a gradient and setting the colors to fade from orange to red. We can also adjust the alpha value of the color to make the particles fade out and create an interesting effect.

We can then change the Shape property (under the Shape module) to a sphere and adjust the Radius property to make the particles spawn from a sphere. I set my radius to 0.1.

We can then change the Size over Lifetime property to make the particles bigger. However, I was taking some creative liberty and switched the material of the particle system (under the Renderer module) to Sprites-Default which changed the shape of the particles to a square that is fairly large in size. I then changed the Max Particle Size to 0.35 to make the particles slightly smaller that the sprite default size.

I adjust the Start Lifetime to 1 and the Start Speed to 1 to make the particles look more like an explosion.

The end results look like this: Explosion VFX

Using the Effect​

Now that we have the effect, we must integrate it into our game. We can drag and drop the ExplosionVFX gameobject into our prefabs folder to create a prefab that we can spawn in our game when an enemy dies. I'm going to add a variable called ExplosionVFX in our health script to get a reference to a GemeObject and we will spawn this GameObject when the health reaches 0.

[SerializeField] protected GameObject ExplosionVFX = null;

// in apply damage function
// if the health drops below zero destroy the object
if (hp <= 0)
{
    // Spawn the explosion effect if available
    if(ExplosionVFX)
    {
        // the explosion effect has a self destruct which will handle destroying itself
        Instantiate(ExplosionVFX, transform.position, Quaternion.identity);
    }
}

I'm adding a null check to make sure that the ExplosionVFX is only spawned if it's available. Let's say we don't attach a VFX to the player object, then when the player dies we don't spawn an explosion effect. The last thing we to do is drag and drop the ExplosionVFX prefab into the Explosion VFX field in the health component of the enemy prefab.

Let's test it out and see how it looks. When the enemy dies, we should see an explosion effect. Great! But there's an issue. The explosion effect keeps playing forever and ever. We need to make sure that the effect is destroyed after a certain amount of time.

Self Destruct​

We can introduce a new script called SelfDestruct that will destroy the gameobject it is attached to after a certain amount of time. By keeping track of float called duration that ticks down, we can accomplish this.

[SerializeField] float duration = 1;

void Update()
{
    duration -= Time.deltaTime;
    if(duration <= 0)
    {
        Destroy(gameObject);
    }
}

We can then attach this script to the ExplosionVFX prefab and set the duration to 0.5. Now when the enemy dies, the explosion effect will play for 0.5 seconds and then destroy itself.

Conclusion​

The particle system is very powerful and can make the game look a lot more polished. However, using it is less of a science and more of an art. Most of the time, I find myself experimenting with the various values and properties, tweaking them until I get the desired effect. Even though the system might feel a bit overwhelming at first, with a little bit of practice and experimentation, you'll be able to master it in no time.

Next Steps​

Why not try to create a trail effect for the projectiles? Or maybe a smoke effect for the player when they take damage? The possibilities are endless.

Final Scripts​

using UnityEngine;

public class SelfDestruct : MonoBehaviour
{
    [SerializeField] float duration = 1;

    void Update()
    {
        duration -= Time.deltaTime;
        if(duration <= 0)
        {
            Destroy(gameObject);
        }
    }
}