我正在努力学习python，现在我正在玩外星人入侵游戏。我在你让外星人向右移动的地方，但由于某种原因，外星舰队根本不动。每当我让它移动时，要么只有边缘在外星人就位的情况下移动，要么整个舰队以一种奇怪的方式移动(附图片(image1
图像2
alin_invasion.py
```
import sys
import pygame
from settings import settings
from ship import Ship
from bullets import Bullet
from alien import Alien
class AlienInvasion:
"""overall class to manage game assets and behaviours"""
def __init__(self):
"""initialise game and create game resources"""
pygame.init()
self.settings=settings()
self.screen=pygame.display.set_mode((self.settings.screen_width,self.settings.screen_height))
pygame.display.set_caption("Alien Invasion")
self.ship=Ship(self)
self.bullets=pygame.sprite.Group()
self.aliens=pygame.sprite.Group()
def run_game(self):
"""start main loop for the game"""
while True:
self._check_events()
self.ship.update()
self._update_bullets()
self._create_fleet()
self._update_screen()
self._update_aliens()
def _check_events(self):
#watch for keyboard and mouse events.
for event in pygame.event.get():
if event.type==pygame.QUIT:
sys.exit()
elif event.type==pygame.KEYDOWN:
self._check_KEYDOWN_events(event)
elif event.type==pygame.KEYUP:
self._check_KEYUP_events(event)
def _check_KEYDOWN_events(self,event):
"""respond to keypresses."""
if event.key==pygame.K_RIGHT:
self.ship.moving_right=True
elif event.key==pygame.K_LEFT:
self.ship.moving_left=True
elif event.key==pygame.K_SPACE:
self._fire_bullet()
elif event.key==pygame.K_q:
sys.exit()
elif event.key==pygame.K_f:
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
def _check_KEYUP_events(self,event):
"""respond to key releases."""
if event.key==pygame.K_RIGHT:
self.ship.moving_right=False
elif event.key==pygame.K_LEFT:
self.ship.moving_left=False
def _fire_bullet(self):
"""create a new bullet and add it to the bullet group"""
if len(self.bullets) < (self.settings.bullets_allowed):
new_bullet=Bullet(self)
self.bullets.add(new_bullet)
def _update_bullets(self):
"""Update position of bullets and get rid of old bullets."""
# Update bullet positions.
self.bullets.update()
#getting rid of old fired bullets
for bullet in self.bullets.copy():
if bullet.rect.bottom <= 0:
self.bullets.remove(bullet)
def _update_aliens(self):
"""initialise right movement of aliens to right"""
self.aliens.update()
def _create_fleet(self):
"""create the fleet of aliens"""
#creating an alien and find the the number of aliens in a row.
#spacing between each alien is one alien width.
alien=Alien(self)
alien_width, alien_height= alien.rect.size
alien_width=alien.rect.width
available_space_x=self.settings.screen_width-(2*alien_width)
number_aliens_x=available_space_x//(2*alien_width)
#determine number of rows that fit on the screen
ship_height=self.ship.rect.height
available_space_y = (self.settings.screen_height - (3 * alien_height) - ship_height)
number_rows = available_space_y // (2 * alien_height)
#create full fleet of aliens.
for row_number in range(number_rows):
for alien_number in range(number_aliens_x):
self._create_alien(alien_number, row_number)
def _create_alien(self,alien_number, row_number):
#create an alien and place it in the row.
alien=Alien(self)
alien_width, alien_height= alien.rect.size
alien_width=alien.rect.width
alien.x=alien_width + 2 * alien_width * alien_number
alien.rect.x=alien.x
alien.rect.y=alien.rect.height + 2 * alien.rect.height * row_number
self.aliens.add(alien)
def _check_fleet_edges(self):
"""respond appropriately if any aliens have reached the edge"""
for alien in self.aliens.sprites():
if alien.check_edges():
self._change_fleet_direction()
break
def _change_fleet_direction(self):
"""drop entire fleet and change direction"""
for alien in self.aliens.sprites():
alien.rect.y += self.settings.fleet_drop_speed
self.settings.fleet_direction *= -1
def _update_screen(self):
"""update images on the screen and flip to the new screen."""
self.screen.fill(self.settings.bg_color)
self.ship.blitme()
for bullet in self.bullets.sprites():
bullet.draw_bullet()
self.aliens.draw(self.screen)
#make the most recently drawn screen visible,
pygame.display.flip()
if __name__=='__main__':
#make a game instance and run the game.
ai=AlienInvasion()
ai.run_game()
```
发货.py
```
import pygame
class Ship:
"""a class to manage the ship"""
def __init__(self,ai_game):
"""initialize the ship and set its starting position."""
self.screen=ai_game.screen
self.settings=ai_game.settings
self.screen_rect=ai_game.screen.get_rect()
#load the ship image and its rect.
self.image=pygame.image.load('images/ship.bmp')
self.rect=self.image.get_rect()
#start each new ship at the bottom center of the screen.
self.rect.midbottom=self.screen_rect.midbottom
#store a decimal value for ship's horizontal position.
self.x=float(self.rect.x)
#movement_flags
self.moving_right=False
self.moving_left=False
def update(self):
#update ship's position based on movement flags
#update the ship's x value, not the rect.
if self.moving_right and self.rect.right < self.screen_rect.right:
self.x += self.settings.ship_speed
if self.moving_left and self.rect.left > 0:
self.x -= self.settings.ship_speed
#update rect object from self.x
self.rect.x=self.x
def blitme(self):
"""draw the ship st its current location."""
self.screen.blit(self.image,self.rect)
alien.py
import pygame
from settings import settings
from pygame.sprite import Sprite
class Alien(Sprite):
"""A class to represent a single alien in the fleet."""
def __init__(self,ai_game):
"""initialise alien and set its starting position"""
super().__init__()
self.screen=ai_game.screen
self.settings=ai_game.settings
#load alien image and set its rect attribute.
self.image=pygame.image.load('images/corona.bmp')
self.rect=self.image.get_rect()
#start the alien on top left corner of the screen.
self.rect.x=self.rect.width
self.rect.y=self.rect.height
#store exact rect position of the alien.
self.x=float(self.rect.x)
def check_edges(self):
"""Return True if alien is at edge of screen."""
screen_rect = self.screen.get_rect()
if self.rect.right >= screen_rect.right or self.rect.left<=0:
return True
def update(self):
"""make the aliens move right"""
self.x += (self.settings.alien_speed * self.settings.fleet_direction)
self.rect.x=self.x
设置.py
class settings:
"""a class to store all settings for alien invasion."""
def __init__(self):
"""initialise game's settings"""
#screen settings
self.screen_width=1250
self.screen_height=650
self.bg_color=(103,113,214)
#bullet settings
self.bullets_allowed=10
self.bullet_speed=8
self.bullet_height=15
self.bullet_width=3
self.bullet_color=(255,0,0)
#ship settings
self.ship_speed=1.5
#alien settings
self.alien_speed=1.0
self.fleet_drop_speed=15
# (1) represents fleet direction right and (-1) represents left direction
self.fleet_direction=1
bullets.py
import pygame
from pygame.sprite import Sprite
class Bullet(Sprite):
"""A class to manage bullets fired from the ship"""
def __init__(self,ai_game):
"""create a bullet object at ship's current position"""
super().__init__()
self.screen=ai_game.screen
self.settings=ai_game.settings
self.color=self.settings.bullet_color
#create a bullet rect at (0,0) and then set 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 bullet's position as a decimal value
self.y=float(self.rect.y)
def update(self):
"""move the bullet up the screen"""
#update decimal position 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)
这是一个相当简单的错误：
def run_game(self):
"""start main loop for the game"""
while True:
self._check_events()
self.ship.update()
self._update_bullets()
self._create_fleet() # <<-- HERE
self._update_screen()
self._update_aliens()
print( "Aliens: " + str( len( self.aliens ) ) )
每一次屏幕绘制，它都会调用_create_fleet()，这会向self.aliens精灵组添加更多的外星人。
所以你看到的不是原来的外星人在搞笑，而是新的外星人在添加，位图在一起接吻(这是一个技术术语；(
如果你把我上面添加的print()包括在你的主循环中，那就很清楚了：
user@linux# python3 ./bad_aliens.py
pygame 2.0.1 (SDL 2.0.14, Python 3.6.9)
Hello from the pygame community. https://www.pygame.org/contribute.html
Aliens: 144
Aliens: 288
Aliens: 432
Aliens: 576
...
几秒钟后；10000名外国人。Eeek！
也许你想要的是这样的东西：
def run_game(self):
"""start main loop for the game"""
self._create_fleet() # Make some aliens (just once)
while True:
self._check_events()
self.ship.update()
self._update_bullets()
self._update_screen()
self._update_aliens()