Lesson 3: Shooting Bullets

Objective 🧐🗿

We are now going to make our peashooter shoot! Before we start here, make sure you are able to plant the peashooters on your grids from last session.

Introducing Shooting Mechanics 👾🔫

Create the Bullet

We will need to create a new object that is going to represent our bullet.

It will have three components:

1. Rigidbody2D
2. Box collider2D
3. Bullet Script (NOOOOO NOT SCRIPTING AGAIN)

Make sure to change some of the properties to your likings, remember to turn gravity scale to 0.

Create the Bullet Origin

Since our peashooter does not have the bullets with it, we need to:

• Add a new empty object in the peashooter as the bullet origin, or where the bullet will come out from.

We can do this by:

1. Going inside of the peashooter object,
2. Move the empty object inside it so it becomes a child of the peashooter,
3. Adjust the position of the bullet origin and put it near his mouth (or somewhere else).

Now we are ready to script.

Create the Bullet Script

public class Shoot : MonoBehaviour

   Declare variables:
     - damage: an integer for the damage the bullet will cause
     - speed: a float for the bullet's movement speed

   Start method:
     - Destroy the bullet after 10 seconds

   Update method:
     - Every frame, move the bullet forward along the x-axis by "speed * Time.deltaTime"

   OnTriggerEnter2D method:
     - This method is triggered when the bullet collides with another object
     - Check if the object the bullet collided with is a Zombie (ZombieScript attached)

     If the collided object is a Zombie:
       - Call the 'hit' method on the ZombieScript, passing 'damage' and 'freeze' as arguments
       - Destroy the bullet to simulate it hitting the target

Create the Shoot Script

Now we have a bullet script, we also need a shoot script that we put inside our peashooter so it can shoot out the bullets.

We will have to make a new script component inside the peashooter and we will begin scripting! (YAY)

This will be a big chunk of code, so if you ever need to double check and slow down don't be disencouraged to do so.

Here is the pseudocode instructions:

   Declare variables:
     - bullet: a GameObject reference for the bullet to be shot
     - shootPosition: a Transform where bullets will be instantiated from
     - cooldown: a float representing the time between shots
     - canShoot: a boolean to control when the shooter can fire next
     - range: a float defining how far the shooter can detect targets
     - shootMask: a LayerMask determining which layers the raycast can hit
     - target: a GameObject that will store the currently detected target

    Start method:
     - Invoke the ResetCooldown method after a delay equal to 'cooldown' to allow shooting

   Update method:
     - Perform a raycast starting from the current position going right, up to 'range', and only hitting objects on the 'shootMask' layer
     - If the raycast hits a collider:
         - Set 'target' to the GameObject hit by the raycast
         - Call the Fire method

   ResetCooldown method:
     - Set 'canShoot' to true to enable shooting

   Fire method:
     - If 'canShoot' is false, exit the method to prevent firing
     - Set 'canShoot' to false to enforce cooldown
     - Invoke the ResetCooldown method after 'cooldown' seconds to reset the shooting ability
     - Instantiate a bullet at 'shootPosition' with default orientation (no rotation)

If the peashooter is now shooting at the zombies, you are done! Next chapter we will be making the sun and sunflowers to get more peashooters!