python速成班13-4添加一排新的精灵滞后于pygame，而新行不移动。

Question

我目前正在pyton速成班上做一个练习，修改练习13-3中的代码，这样当一排雨滴从屏幕底部消失时，屏幕顶部就会出现新的一行，并开始下降。当底部一行接触到屏幕底部时，我设法使一排新的雨滴出现。然后，游戏开始明显滞后，在屏幕顶部创建了一排新的雨滴之后，新的行保持不变，而原来的雨滴继续向下移动(明显滞后)。我已经做了一些调试，当第一行触及底部时，似乎会创建大量的新行，但我不知道为什么。感谢您的帮助，谢谢yoU！

stars_game.py

import sys
import pygame
from settings import Settings
from star import Star
from random import randint

class StarGame:

    def __init__(self):
        pygame.init()
        self.settings = Settings()
        self.screen = pygame.display.set_mode(
            (0,0), pygame.FULLSCREEN)
        self.settings.screen_width = self.screen.get_rect().width 
        self.settings.screen_height = self.screen.get_rect().height
        pygame.display.set_caption("Star Game")

        self.stars = pygame.sprite.Group()

        self._create_fleet()



    def run_game(self):
        while True:
            self._check_events()
            self._update_stars()
            self._update_screen()

            
    def _create_fleet(self):
        star = Star(self)
        star_width, star_height = star.rect.size
        available_space_x = self.settings.screen_width - (2 * star_width) 
        number_stars_x = available_space_x // (2 * star_width)

        available_space_y = (self.settings.screen_height - 2 * star_height)
        number_rows = available_space_y // (2 * star_height)
        for row_number in range(number_rows):
            for star_number in range(number_stars_x):
                    self._create_star(star_number, row_number)
            
    def _create_row(self):
        star = Star(self)
        star_width, star_height = star.rect.size
        available_space_x = self.settings.screen_width - (2 * star_width) 
        number_stars_x = available_space_x // (2 * star_width)

        available_space_y = (self.settings.screen_height - 2 * star_height)
        number_rows = available_space_y // (2 * star_height)
        for star_number in range(number_stars_x):
            self._create_star(star_number, 0)

    def _create_star(self, star_number, row_number):
        star = Star(self)
        star_width, star_height = star.rect.size
        star.x = star_width + 2 * star_width * star_number
        star.rect.x = star.x
        star.y = star.rect.height + 2 * star.rect.height * row_number
        star.rect.y = star.y
        self.stars.add(star)

    def _update_stars(self):
        """Update the positions of all stars in the fleet."""
        self._check_fleet_edges()
        self.stars.update()

    def _check_events(self):
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                sys.exit()
            elif event.type == pygame.KEYDOWN:
                if event.key == pygame.K_q:
                    sys.exit()

    def _update_screen(self):
        self.screen.fill(self.settings.bg_color)
        self.stars.draw(self.screen)
        pygame.display.flip()

    def _check_fleet_edges(self):
        flag = False
        for star in self.stars.sprites():
            if star.check_edges():
                star.remove()
                flag = True
        if flag:
            self._create_row()
            print("NEW")


if __name__ == '__main__':
    sg = StarGame()
    sg.run_game()

settings.py

class Settings:
    """A class to store all settings for Alien Invasion."""

    def __init__(self):
        """Initialise the game's settings."""
        #Screen settings
        self.screen_width = 1200
        self.screen_height = 800
        self.bg_color = (230, 230, 230)

        self.star_speed = 1.0

star.py

import pygame
from pygame.sprite import Sprite 

class Star(Sprite):

    def __init__(self, sg_game):
        super().__init__()
        self.screen = sg_game.screen
        self.settings = sg_game.settings

        self.image = pygame.image.load('images/alien.bmp')
        self.rect = self.image.get_rect()
        self.rect.x = self.rect.width
        self.rect.y = self.rect.height
        self.x = float(self.rect.x)
        self.y = float(self.rect.y)

    def update(self):
        self.y += self.settings.star_speed
        self.rect.topleft = round(self.x), round(self.y)

    def check_edges(self):
        screen_rect = self.screen.get_rect()
        if self.rect.y >= screen_rect.bottom:
            return True

Answer 1

当星星在屏幕底部时，它们需要从stars Group中移除。您必须将从其中移除恒星的组传递给remove方法。或者，您可以使用kill从所有组中移除一颗恒星。

class StarGame:
    # [...]

    def _check_fleet_edges(self):
        flag = False
        for star in self.stars.sprites():
            if star.check_edges():
                
                star.remove(self.stars)          # <---
                # alternatively you can do
                # star.kill()     
           
                flag = True
        if flag:
            self._create_row()
            print("NEW")

pygame.image.load是一个非常耗时的操作。必须读取和解码图像文件。在初始化期间加载一次映像，并将加载的Surface对象传递给Star的构造函数

class Star(Sprite):

    def __init__(self, sg_game, image):
        # [...]

        self.image = image
        
        # [...]

class StarGame:
    def __init__(self):
        # [...]

        self.star_surf = pygame.image.load('images/alien.bmp')

    # [...]

    def _create_fleet(self):
        star = Star(self, self.star_surf) 
        # [...]

    def _create_row(self):
        star = Star(self, self.star_surf)
        # [...]

    def _create_star(self, star_number, row_number):
        star = Star(self, self.star_surf)
        # [...]