Lesson 14

Top-Down Shooter

The Player Class

from pycat.core import Color, Sprite, Window

window = Window()


class Player(Sprite):

    def on_create(self):
        self.color = Color.AMBER
        self.scale = 30
        self.speed = 10

    def on_update(self, dt):
        if window.is_key_pressed('w'):
            self.y += self.speed
        # fill in code for keys A, S, D


player = window.create_sprite(Player)
window.run()

Extensions:

  • set your player’s initial position

  • add a key to make your player teleport

  • add a method to reset your player’s position

  • add properties to store your player’s hp, strength, defense, magic, etc.

The PlayerBullet Class

We will fire bullets from the player whenever the mouse is clicked.

Implement your PlayerBullet class.

  • Set self.scale, self.color, self.position

  • Add a new property for bullet speed e.g. self.speed

  • Set rotation with self.point_toward_mouse_cursor()

  • Bullets move foward, i.e. self.move_forward(self.speed)

  • self.delete() if self.is_touching_window_edge()

Add the following method to your Player class.

def on_left_click_anywhere(self):
    window.create_sprite(PlayerBullet)

Extensions:

  • Give your player a maximum number of bullets they can fire

  • Add a power property to your Bullet class

  • Add a PowerUp class that the player can collect to increase power

The Enemy Class

In the Enemy class:

  • Enemys start at a random position i.e. self.goto_random_position()

  • Enemys start with a random rotation, i.e. self.rotation = randint(0, 360)

  • Add a speed property and move each enemy forward

  • Delete an an enemy when they touch the window’s edge

You will need the Scheduler class and the randint function.

from pycat.core import Scheduler
from random import randint

Spawn the enemies using the Scheduler.update() method.

def spawn_enemy():
    window.create_sprite(Enemy)


Scheduler.update(spawn_enemy, delay=1)

Extensions:

  • Spawn enemies only if they are farther than some distance from the player. You can use the method self.distance_to(player.position)

  • Spawn enemies on the window edge. How can you keep them from being immediately deleted?

PlayerBullet - Enemy Interaction

  • self.add_tag('pbullet') to our PlayerBullet class

  • delete enemies if self.is_touching_any_sprite_with_tag('pbullet')

Extensions:

  • add hp to your Enemy class so that they die after multiple hits

  • When an enemy is hit you could also

    • change color, and/or opacity

    • create a particle effect animation

The EnemyBullet Class

Create an EnemyBullet class with properties:

  • self.color

  • self.scale

  • self.speed

The enemy bullets should be deleted if:

  • self.is_touching_window_edge()

  • self.is_touching_sprite(player)

We want each of our enemies to fire bullets at the player every 2 seconds.

  • add a self.time to the Enemy class

  • update self.time in on_update(self, dt)

  • if self.time > 2 then create a bullet and set it’s position/rotation

EnemyBullet - Player Interaction

  • self.add_tag('ebullet') to our EnemyBullet class

  • delete player if self.is_touching_any_sprite_with_tag('ebullet')

Extensions:

  • add hp to your Player class so that they die after multiple hits

  • When a player is hit you could also:

    • change color, and/or opacity

    • create a particle effect animation