bullet.py

import pygame
from pygame.sprite import Sprite

class Bullet(Sprite):
    """ A class to manage bullet fired from the ship. """ 

    def __init__(self, ai_game):
        """ Create bullet object at ships position. """ 
        super().__init__()
        self.screen = ai_game.screen
        self.settings = ai_game.settings 
        self.color = self.settings.bullet_color

        #create a bullet rect aat (0,0) and then set the correct position. 
        self.rect = pygame.Rect(0, 0, self.settings.bullet_width, self.settings.bullet_height)
        self.rect.midtop = ai_game.ship.rect.midtop

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


    def update(self):
        """ Move the bullet up the screen. """ 
        #Update the decimal positions of the bullet. 
        self.y -= self.settings.bullet_speed 
        #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)