在游戏“外星人入侵”中，为什么我的外星人只出现了一排？
问题描述
(instance.py)
import pygame
from settings import Settings
from ship import Ship
import game_functions as gf
def run_game():
pygame.init()
ai_settings = Settings()
screen = pygame.display.set_mode(
(ai_settings.screen_width,ai_settings.screen_height))
pygame.display.set_caption('Alien Invasion')
ship = Ship(ai_settings,screen)
bullets = pygame.sprite.Group()
aliens = pygame.sprite.Group()
gf.create_fleet(ai_settings,screen,ship,aliens)
while 1:
gf.check_events(ai_settings,screen,ship,bullets)
ship.update()
gf.update_bullet(bullets)
gf.update_alien(ai_settings,aliens)
gf.update_screen(ai_settings,screen,ship,bullets,aliens)
run_game()
(Game_functions.py)
import pygame
import sys
from bullet import Bullet
from alien import Alien
def check_events(ai_settings,screen,ship,bullets):
for event in pygame.event.get():
if event.type == pygame.KEYDOWN:
check_keydown_events(ai_settings,screen,ship,bullets,event)
if event.type == pygame.KEYUP:
check_keyup_events(ship,event)
def check_keydown_events(ai_settings,screen,ship,bullets,event):
if event.key == pygame.K_RIGHT:
ship.moving['right'] = True
elif event.key == pygame.K_LEFT:
ship.moving['left'] = True
elif event.key == pygame.K_UP:
ship.moving['up'] = True
elif event.key == pygame.K_DOWN:
ship.moving['down'] = True
elif event.key == pygame.K_SPACE:
new_bullet = Bullet(ai_settings,screen,ship)
bullets.add(new_bullet)
elif event.key == pygame.K_q:
sys.exit()
def check_keyup_events(ship,event):
if event.key == pygame.K_RIGHT:
ship.moving['right'] = False
elif event.key == pygame.K_LEFT:
ship.moving['left'] = False
elif event.key == pygame.K_UP:
ship.moving['up'] = False
elif event.key == pygame.K_DOWN:
ship.moving['down'] = False
def update_screen(ai_settings,screen,ship,bullets,aliens):
screen.fill(ai_settings.bg_color)
ship.blitme()
for bullet in bullets.sprites():
bullet.draw_bullet()
aliens.draw(screen)
pygame.display.flip()
def update_bullet(bullets):
bullets.update()
for bullet in bullets.copy():
if bullet.rect.y < 0:
bullets.remove(bullet)
def create_fleet(ai_settings,screen,ship,aliens):
sample_alien = Alien(ai_settings,screen)
alien_width = sample_alien.rect.width
alien_height = sample_alien.rect.height
available_space_x = ai_settings.screen_width - 2 * alien_width
numbers_alien_x = int(available_space_x / ( 2 * alien_width ))
available_space_y = ai_settings.screen_height - 3 * alien_height - ship.rect.height
numbers_alien_y = int(available_space_y / ( 2 * alien_height ))
for number_alien_y in range(numbers_alien_y):
for number_alien_x in range(numbers_alien_x):
alien = Alien(ai_settings,screen)
alien.rect.x = alien_width + 2 * alien_width * number_alien_x
alien.rect.y = alien_height + 2 * alien_height * number_alien_y
aliens.add(alien)
def update_alien(ai_settings,aliens):
check_fleet_edges(ai_settings,aliens)
aliens.update()
def check_fleet_edges(ai_settings,aliens):
for alien in aliens.sprites():
if alien.check_edges():
change_fleet_direction(ai_settings,aliens)
break
def change_fleet_direction(ai_settings,aliens):
for alien in aliens.sprites():
alien.rect.y += ai_settings.fleet_drop_speed
ai_settings.fleet_direction *= -1
(settings.py)
class Settings(object):
def __init__(self):
self.screen_width = 1200
self.screen_height = 700
self.bg_color = 230,230,230
self.ship_speed_factor = 1.5
self.bullet_width = 3
self.bullet_height = 15
self.bullet_color = 15,15,15
self.bullet_speed_factor = 1
self.alien_speed_factor = 2
self.fleet_drop_speed = 10
self.fleet_direction = 1
(ship.py)
import pygame
class Ship(object):
def __init__(self,ai_settings,screen):
self.ai_settings = ai_settings
self.screen = screen
self.image = pygame.image.load('images/ship.bmp')
self.rect = self.image.get_rect()
self.screen_rect = self.screen.get_rect()
self.rect.centerx = self.screen_rect.centerx
self.rect.bottom = self.screen_rect.bottom
self.moving = {'right':False,'left':False,'up':False,'down':False}
self.centerx = float(self.rect.centerx)
self.centery = float(self.rect.centery)
self.speed = self.ai_settings.ship_speed_factor
def update(self):
if self.moving['right'] and self.rect.right < self.ai_settings.screen_width:
self.centerx += self.speed
if self.moving['left'] and self.rect.left > 0:
self.centerx -= self.speed
if self.moving['up'] and self.rect.top > 0:
self.centery -= self.speed
if self.moving['down'] and self.rect.bottom < self.ai_settings.screen_height:
self.centery += self.speed
self.rect.centerx = self.centerx
self.rect.centery = self.centery
def blitme(self):
self.screen.blit(self.image,self.rect)
(bullet.py)
import pygame
from random import randint
class Bullet(pygame.sprite.Sprite):
def __init__(self,ai_settings,screen,ship):
super().__init__()
self.ai_settings = ai_settings
self.screen = screen
self.ship = ship
self.rect = pygame.Rect(0,0,self.ai_settings.bullet_width,self.ai_settings.bullet_height)
self.rect.top = self.ship.rect.top
self.rect.centerx = self.ship.rect.centerx
self.speed = self.ai_settings.bullet_speed_factor
self.y = float(self.rect.y)
self.color = randint(1,255),randint(1,255),randint(1,255)
def update(self):
self.y -= self.speed
self.rect.y = self.y
def draw_bullet(self):
pygame.draw.rect(self.screen,self.color,self.rect)
(alien.py)
import pygame
class Alien(pygame.sprite.Sprite):
def __init__(self,ai_settings,screen):
super().__init__()
self.ai_settings = ai_settings
self.screen = screen
self.image = pygame.image.load('images/alien.bmp')
self.rect = self.image.get_rect()
self.speed = self.ai_settings.alien_speed_factor
self.x = float(self.rect.x)
self.y = float(self.rect.y)
def check_edges(self):
screen_rect = self.screen.get_rect()
if self.rect.right >= screen_rect.right:
return True
elif self.rect.left <= 0:
return True
def update(self):
self.x += (self.speed * self.ai_settings.fleet_direction)
self.rect.x = self.x
我的目标是在整个屏幕上创建外星舰队。 为什么只有一排外星人？
解决方案
问题是在Alien中update(self)使用self.x的值，但在运行create_fleet(...)时从未设置此值。所以你所有的外星人都已经在那里了，他们只是一个接一个地在上面！
create_fleet(...)中初始化每个Alien时，同时设置self.x和For Eachself.rect.x。所以不是：
alien.rect.x = alien_width + 2 * alien_width * number_alien_x
您将拥有：
alien.rect.x = alien.x = alien_width + 2 * alien_width * number_alien_x
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