background.py

import pygame
import config


class Background:
    def __init__(self, position_x):
        pygame.sprite.Sprite.__init__(self)
        self.position_x = position_x
        self.stars_1_position_x = position_x
        self.stars_2_position_x = position_x
        self.stars_1_speed = config.Constants.BACKGROUND_STARS_1_SPEED
        self.stars_2_speed = config.Constants.BACKGROUND_STARS_2_SPEED
        self.background_img = pygame.image.load('img/background.png').convert()
        self.background_stars_1_img = pygame.image.load('img/background_stars_1.png').convert_alpha()
        self.background_stars_2_img = pygame.image.load('img/background_stars_2.png').convert_alpha()

        self.background_surf = pygame.Surface(config.Constants.SCREEN_SIZE)

    def move(self):
        self.stars_1_position_x += self.stars_1_speed
        self.stars_2_position_x += self.stars_2_speed

    def render(self, surface):
        self.background_surf.blit(self.background_img, (self.position_x, 0))
        self.background_surf.blit(self.background_stars_1_img, (self.stars_1_position_x, 0))
        self.background_surf.blit(self.background_stars_2_img, (self.stars_2_position_x, 0))

        # repeating stars
        if self.stars_1_position_x >= 0:
            self.background_surf.blit(self.background_stars_1_img,
                                      (self.stars_1_position_x - config.Constants.SCREEN_WIDTH, 0))
        if self.stars_2_position_x >= 0:
            self.background_surf.blit(self.background_stars_2_img,
                                      (self.stars_2_position_x - config.Constants.SCREEN_WIDTH, 0))

        surface.blit(self.background_surf, (0, 0))