Unity Fundamentals — Power-Ups

What is a game without power-ups? Not much of a game. So how do you create power-ups and make sure they only last for a while? Let’s have a closer look at power-ups, how to provide them and then limit their duration in this article.

What are Power-Ups?

A power-up is an extra ability that a player can obtain to assist them in playing the game. They are usually an event that a player triggers during gameplay. They can be triggered after inflicting an amount of damage or simply being something a player collects. What the extra ability will be and its duration will depend on the game designer and programmer.

This article will cover how to enable a collectable power-up for a player and limit its duration during gameplay.

Spawning Collectable Power-Ups to a Player

For this article, we will deliver power-ups to the player at a random interval. Within our Spawn Manager script, we create a Coroutine to instantiate the power-ups on a random interval between three seconds and nine seconds.

IEnumerator SpawnPowerUpRoutine()
   {
      while (_stopSpawning == false)
         {
            GameObject powerup = Instantiate(_powerUpPrefab, new Vector3(Random.Range(-2.3f, 2.3f), 8, 0), Quaternion.identity);
            yield return new WaitForSeconds(Random.Range(3, 10));
         }
    }

Although we have specified a random range between 3 and 10 seconds because we are using whole numbers, the largest random number is 9 seconds.

In void Start, the Coroutine must be started for the power-ups to be spawned.

StartCoroutine(SpawnPowerUpRoutine());

Limiting the duration of the Power-Ups

So how do we limit the duration of the power-up that the player collected? You may not want them to continue to use the power-up forever. Back on the Player script, before the void Start function, we create a variable of type bool to determine if the power-up is active or not.

private bool _isPowerUpActive;

Let’s create the Coroutine to limit the duration of the power-up for 5 seconds.

IEnumerator TripleShotInactive()
   {
      while (_isPowerUpActive == true)
         {
            yield return new WaitForSeconds(5);
            _isPowerUpActive = false;
         }
   }

We now create a public function to activate the power-up and start the Coroutine to limit its duration.

public void PowerUp()
   {
       _isPowerUpActive = true;
       StartCoroutine(PowerUpActive());
   }

The final step is for the associated Power-Up script to detect that the player has collected it, enable the power-up and destroy itself.

private void OnTriggerEnter2D(Collider2D other)
   {
       if (other.tag == “Player”)
          {
             Player player = other.transform.GetComponent<Player>();
             if (player != null)
                {
                    player.PowerUp();
                }
             Destroy(this.gameObject);
           }
    }

I hope this article has helped you create and limit power-ups in your game. Let me know what other articles you would like me to write that can help you.