5. Asteroids

Asteroids, based on http://www.multiwingspan.co.uk/micro.php?page=charlie2

The game involves moving a ship, shown on the bottom row of the screen.

The other pixels represents an asteroid that is falling towards the ship.

The player moves the ship left or right by pressing the A & B buttons to avoid contact with an asteroid.

---

5.1. The Asteroids outline

Tasks

1. Here is the outline to the Asteroids code. The game loop has been provided. See if you can write code for each method in the classes to get the game working.

class Asteroid:
    def __init__(self, x, y):
        # initialize the x and y value for an asteroid

    def move(self):
        # move the asteroid down 1 row and if offscreen, reposition in a random position in the top row

class Ship:
    def __init__(self, x, y):
        # initialize the x and y value for the ship

    def move(self):
        # press A to move left and press B to move right and stop on edges of display

class Board:
    def __init__(self):
        # initialize the score to 0;
        # use class composition to position ship in middle of bottom row
        # use class composition to initialize an asteroid in the top row and another in the next row.

    def draw_board(self):
        # use an empty image to position the ship and asteroids and display it

    def move_ship(self):
        # move the ship

    def move_ship_and_asteroids(self):
        # move the ship and asteroids

    def check_not_hit(self):
        # return True if the ship has hit an asteroid

    def update_score(self, score_up=1):
        # increment the score

    def get_score(self):
        # return the score

def PlayGame():
    game_board = Board()
    game_board.draw_board()

    playing = True
    game_speed = 200
    while playing:
        # move ship only
        for i in range(3):
            sleep(game_speed)
            game_board.move_ship()
            game_board.draw_board()
        # move ship and asteroids
        sleep(game_speed)
        game_board.move_ship_and_asteroids()
        game_board.draw_board()
        playing = game_board.check_not_hit()
        if playing:
            game_board.update_score()

    display.scroll(game_board.get_score())



while True:
    display.show(Image.ARROW_W)
    if button_a.was_pressed():
        PlayGame()
    sleep(500)

---

5.2. Working code

The working code is below.

from microbit import *
import random

class Asteroid:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def move(self):
        self.y = self.y + 1
        if self.y == 5:
            self.y = 0
            self.x = random.randint(0, 4)

class Ship:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def move(self):
        if button_a.was_pressed() and self.x != 0:
            self.x = self.x - 1
        elif button_b.was_pressed() and self.x != 4:
            self.x = self.x + 1

class Board:
    def __init__(self):
        self.score = 0
        self.ship = Ship(2, 4)
        self.asteroid1 = Asteroid(random.randint(0, 4), 0)
        self.asteroid2 = Asteroid(random.randint(0, 4), 1)

    def draw_board(self):
        self.board = Image("00000:" * 5)
        self.board.set_pixel(self.ship.x, self.ship.y, 9)
        self.board.set_pixel(self.asteroid1.x, self.asteroid1.y, 5)
        self.board.set_pixel(self.asteroid2.x, self.asteroid2.y, 5)
        display.show(self.board)

    def move_ship(self):
        self.ship.move()

    def move_ship_and_asteroids(self):
        self.ship.move()
        self.asteroid1.move()
        self.asteroid2.move()

    def check_not_hit(self):
        if self.asteroid1.y == 4 and self.ship.x == self.asteroid1.x:
            return False
        if self.asteroid2.y == 4 and self.ship.x == self.asteroid2.x:
            return False
        return True

    def update_score(self, score_up=1):
        self.score += score_up

    def get_score(self):
        return self.score

def PlayGame():
    game_board = Board()
    game_board.draw_board()

    playing = True
    game_speed = 200
    while playing:
        # move ship only
        for i in range(3):
            sleep(game_speed)
            game_board.move_ship()
            game_board.draw_board()
        # move ship and asteroids
        sleep(game_speed)
        game_board.move_ship_and_asteroids()
        game_board.draw_board()
        playing = game_board.check_not_hit()
        if playing:
            game_board.update_score()

    display.scroll(game_board.get_score())



while True:
    display.show(Image.ARROW_W)
    if button_a.was_pressed():
        PlayGame()
    sleep(500)

---

Tasks

1. Add sounds.

2. Add a flashy start and end animation.

3. Modify the code to speed up the game as the score increases.

4. Modify the code to use more asteroids as the score increases.

5. Modify the code to use levels with a screen indicating the new level.