Creating a Powerup system (Game Dev day 19)

Objective: Create a speed boost powerup for the player character

Demonstration of completed power up.

Let’s break this down logically before we get into the coding necessary to make this happen. We need to be able to increase the movement speed value of the player character when a certain condition is met. In this example, we the player has collided with a power up. You could also do this with a key press (Holding shift makes you move faster).

So first thing is we need to set a parameter on the player for the boosted movement speed. This will be a variable in our Player.cs script, and we will name it _Boostedspeed and we will set it to a value of 8 (our base speed value was set to 5).

This should be in your “public class Player : MonoBehaviour” of the Player.cs.

So now we have the variable set, so our script can understand the concept of a boosted movement speed. However, right now there is now method to actually achieve the movement boost. The next thing we need to do is create the powerup “Speed” itself.

Start off by creating an Empty Gameobject. I am going to name it Speed_Powerup for organizations sake.

Right click your Hierarchy to make the Empty Gameobject.

Right now there is no sprite associated with this powerup, so lets give it a graphic (See my day 17 tutorial for an in depth animation guide).

Our sprite.

Place your sprite frames into the Unity Animation window and record the animation. It should look like this when completed.

Basic 2D animated powerup.

Great! now we have the physical object. However, we need to add a few things to it to make it play nice with our scripts. Seeing as we are going to need to “pickup” this powerup, it will need a Rigidbody and a Collider (Make sure both are 2D)

You need both the RigidBody and the Collider to make this work.

Now its time to code the logic for this system to work. We are going to make a powerup.cs script and attach it to our Speed_Powerup gameobject. Drag and drop your new script onto the Speed_Powerup Gameobject in the hierarchy.

Drag and drop.

Now open up that Powerup.cs script.

Now we want this powerup to fall down the screen towards the player, just like our enemies do. So let’s start off with that.

All we need is a transform.translate in void Update. Let’s also set a limit so that if the powerup goes below the player’s screen, it despawns.

3 Lines of code will achieve the above objectives.

That’s great, but right now nothing will cause this powerup to spawn. Just like our enemies, we need to set spawning parameters. The good news is we can use the same Spawn Manager as we used to set up our enemy spawns.

Let’s open up that C# script now.

We are going to need a coroutine for the powerup spawns, again just like our enemy spawn coroutine. First let’s set a variable for the powerups in the SpawnManager.cs. We will call it _powerups.

The new variable, as well as the previous variables used by this script.

Let’s make that coroutine. First, take a look at the Enemy spawn coroutine we built previously.

This is our coroutine that spawns our enemy spacecraft.

Our powerup spawn coroutine is extremely similar, but we will change a few values and add a line of code to support multiple types of powerups.

This coroutine handles the spawning of all of our powerups.

The first line of code is 1:1, it handles the position the powerup will spawn at. It spawns just off screen, the same as the enemies.

The second line allows us to create multiple powerups to be handled by the same spawning coroutine. We have already made the triple shot, and we will be making a shield after we finish the speed boost (hence the range).

The third line instantiates whatever powerup was selected.

Finally, the fourth and final line sets this coroutine to loop after a delay between 3–8 seconds.

Make sure you add this coroutine to void Start in the script, otherwise it won’t do anything!

Both the enemy and powerup coroutines in void Start.

Let’s move back to our Powerup.cs script. We need to set what effect the player should receive when colliding with whatever powerup spawns.

The Collision effect logic.

Remember the range we put on the SpawnManager?

int randomPowerUp = Random.Range(0, 3);

This is where that logic is used.

Based on the value of that random number, we will get a different powerup. We use Getcomponent to interact with the player (because that’s where we are going to code the actual effects of the powerup) and then use a switch command to have multiple outcomes dependent on which powerup we collide with.

Let’s move to the final script we need to interact with, the Player.cs and let’s review the triple shot powerup’s logic.

Logic for Triple Shot.

We are going to do the same exact thing for the Speed boost powerup.

Logic for the Speed Boost.

One last thing to do is drag your Speed_Powerup gameobject into the Powerups component of your Spawn_Manager.

Make sure you link the powerup to the Spawn Manager or it will never spawn!

And that’s it! We now have 2 working powerups, and are going to make a third next (a shield that will block a hit from an enemy).

Unity Developer