CODEWITHSUNDEEP
python
xHoudek
xHoudek

Reputation: 115

Python Crash Course game: Bullets not firing

My Alien Invasion game does not show bullets being fired. I am copying most of the code from the Python Crash Course book (with minor changes here and there), so I'm guessing it is due to a syntax error that I can't find.

I've looked over the code in the book and tried to find differences between them. I changed K_SPACE to K_w to see if the spacebar wasn't registering or something like that, but the bullets still would not fire.

alien_invasion.py

import pygame
from pygame.sprite import Group
from settings import Settings
from ship import Ship
import game_functions as gf

def run_game():
    # initialize game and create a screen object
    pygame.init()
    ai_settings = Settings()
    screen = pygame.display.set_mode(
        (ai_settings.screen_width, ai_settings.screen_height))
    pygame.display.set_caption('Alien Invasion')

    # set the background color
    bg_color= ai_settings.bg_color

    # make a ship
    ship = Ship(ai_settings, screen)
    # make a group to store bullets in 
    bullets = Group()

    # start the main loop for the game
    running = True
    while running:

        running = gf.check_events(ai_settings, screen, ship, bullets)
        ship.update()
        bullets.update()
        gf.update_screen(ai_settings, screen, ship, bullets)

    pygame.quit()

run_game()

game_functions.py

import pygame
from bullet import Bullet

def check_events(ai_settings, screen, ship, bullets):
    """respond to keypresses and mouse events"""
    running = True
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False # different from Python Crash Course

        elif event.type == pygame.KEYDOWN:
            check_keydown_events(event, ai_settings, screen, ship, bullets)

        elif event.type == pygame.KEYUP:
            check_keyup_events(event, ship)

    return running

def update_screen(ai_settings, screen, ship, bullets):
    """update images on the screen and flip to the new screen"""
    # redraw the screen during each pass through the loop
    screen.fill(ai_settings.bg_color)
    ship.blitme()

    # make the most recently drawn screen visible
    pygame.display.flip()

    # redraw all bullets behind ship and aliens
    for bullet in bullets.sprites():
        bullet.draw_bullet()

def check_keydown_events(event, ai_settings, screen, ship, bullets):
    """respond to keypresses"""
    if event.key == pygame.K_d:
        ship.moving_right = True
    elif event.key == pygame.K_a:
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        # create a new bullet and add it to the bullets groups
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)

def check_keyup_events(event, ship):
    """respond to key releases"""
    if event.key == pygame.K_d:
        ship.moving_right = False
    elif event.key == pygame.K_a:
        ship.moving_left = False

bullet.py

import pygame
from pygame.sprite import Sprite

class Bullet(Sprite):
    """a class to manage bullets fired from the ship"""

    def __init__(self, ai_settings, screen, ship):
        """create a bullet object at the ship's current position"""
        super().__init__()
        self.screen = screen

        # create a bullet rect at (0, 0) and then set correct position
        self.rect = pygame.Rect(0, 0, ai_settings.bullet_width, ai_settings.bullet_height)
        self.rect.centerx = ship.rect.centerx
        self.rect.top = ship.rect.top

        # store the bullet's position as a decimal value
        self.y = float(self.rect.y)

        self.color = ai_settings.bullet_color
        self.speed_factor = ai_settings.bullet_speed_factor

    def update(self):
        """move the bullet up the screen"""
        # update the decimal position of the bullet
        self.y -= self.speed_factor
        # update the rect position
        self.rect.y = self.y

    def draw_bullet(self):
        """draw the bullet to the screen"""
        pygame.draw.rect(self.screen, self.color, self.rect)

left out settings.py and ship.py but can provide them if necessary

Expected outcome: bullet go pew pew

Actual outcome: Game does not crash, but nothing happens when spacebar is pressed.

Upvotes: 2

Views: 1113

Answers (1)

jsbueno
jsbueno

Reputation: 110456

The problem seems to be on the update_screen function - you first draw everything, updates the screen, and then draws the bullets, after the screen is updated. Simply moving the call to ...display.flip() to the end of the function might make your bullets show up (unless there is something other that is also wrong).

def update_screen(ai_settings, screen, ship, bullets):
    """update images on the screen and flip to the new screen"""
    # redraw the screen during each pass through the loop
    screen.fill(ai_settings.bg_color)
    ship.blitme()

    # take this out of here

    # pygame.display.flip()

    # redraw all bullets behind ship and aliens
    for bullet in bullets.sprites():
        bullet.draw_bullet()

    # to here
    pygame.display.flip()

Upvotes: 4

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