我有一个问题，我最近两天都被困住了。在嵌套循环中的文件game_function中，我正在创建外星人，当我添加randint来创建随机数量的外星人时，我遇到了问题。并不总是（只是重新运行游戏）但有时当我检测到精灵边缘作为异形类别的方法时，外星人/精灵不会改变方向，沿着x轴向右移动并且每次通过检查边缘时不断降低外星人。我不知道那到底是什么。在我没有使用randit连续生成随机数的外星人之前，一切都很好。
settings.py
class Settings():
"""A class to store all settings for Alien Invasion"""
def __init__(self):
"""Initialize the game settings"""
#Screen settings
self.screen_width = 1200
self.screen_height = 800
self.bg_color = (230,230,230)
#ship settings
self.ship_speed_factor = 1.5
#Bullet settings
self.bullet_speed_factor = 1
self.bullet_width = 3
self.bullet_height = 15
self.bullet_color = (60, 60, 60)
self.bullets_allowed = 3
# Alien settings
self.alien_speed_factor = 1
self.fleet_drop_speed = 10
# fleet_direction of 1 represents right; -1 represents left.
self.fleet_direction = 1
ship.py
import pygame
class Ship():
def __init__(self,ai_settings, screen):
"""Initialize the ship and sets the starting position."""
self.screen = screen
self.ai_settings = ai_settings
#load the ship image and get its rect
self.image = pygame.image.load('images/ship.png')
self.rect = self.image.get_rect()
self.screen_rect = screen.get_rect()
# Start each new ship at the bottom center of the screen
self.rect.centerx = self.screen_rect.centerx
self.rect.bottom = self.screen_rect.bottom
self.center = float(self.rect.centerx)
#Movement Flag
self.moving_right = False
self.moving_left = False
def update(self):
"""Update the ship's position based on the movement Flag."""
#Update the ship's center value, not the rect
if self.moving_right and self.rect.right < self.screen_rect.right:
self.center += self.ai_settings.ship_speed_factor
if self.moving_left and self.rect.left > 0:
self.center -= self.ai_settings.ship_speed_factor
#update rect object from self.center
self.rect.centerx = self.center
def blitme(self):
"""Draw the ship at its current location"""
self.screen.blit(self.image, self.rect)
在一个函数中，create_fleet（ai_settings，screen，ship，aliens）是嵌套循环，而不是在3-9之间生成随机数，然后在行中放置新实例我使用常量计算，总是在行中给出9个外星人一切都运行得很好。外星人改变了每次方向，只有一次下降，直到下一次check_edge事件超过了条件。所以从一面墙到另一面。现在当randint到位时，并不总是，当check_edge方法确认为true时，然后调用函数change_fleet_direction（）并且在那里我看到问题，它有时不会改变方向。使用方向的地方只是简单的+1或-1，并且在Alien类中调用更新时，它应该减少x轴或增加直到边缘事件。
game_functions.py
import sys
import pygame
from bullet import Bullet
from alien import Alien
from random import randint
def create_fleet(ai_settings, screen, ship, aliens):
"""Create a full fleet of aliens."""
#Create an Alien and find the number of aliens in a row
name= 'First unused'
alien = Alien(ai_settings, screen,name)
number_aliens_x = get_number_aliens_x(ai_settings, alien.rect.width)
number_rows = get_number_rows(ai_settings, ship.rect.height,
alien.rect.height)
# Create the fleet of aliens.
for row_number in range(number_rows):
random_num = randint(3, number_aliens_x)
for alien_number in range(0, random_num):
create_alien(ai_settings, screen, aliens, alien_number,
row_number)
def get_number_aliens_x(ai_settings, alien_width):
"""Determine the number of aliens that fit in a row."""
available_space_x = ai_settings.screen_width - 2 * alien_width
number_aliens_x = int(available_space_x / (2 * alien_width))
return number_aliens_x
def get_number_rows(ai_settings, ship_height, alien_height):
"""Determine the number of rows of aliens that fit on the screen."""
available_space_y = (ai_settings.screen_height -
(3 * alien_height) - ship_height)
number_rows = int(available_space_y / (2 * alien_height))
return number_rows
def create_alien(ai_settings, screen, aliens, alien_number, row_number):
"""Create alien and place it in the row"""
name = "Alien number " + str(alien_number) + " in row " + str(row_number)
alien = Alien(ai_settings, screen, name)
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
aliens.add(alien)
def check_keydown_events(event, ai_settings, screen, ship, bullets):
"""Respond to key presses"""
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_SPACE:
fire_bullet(ai_settings, screen, ship, bullets)
elif event.key == pygame.K_q:
sys.exit()
def fire_bullet(ai_settings, screen, ship, bullets):
# Create a new bullet and add it to the bullets group.
if len(bullets) < ai_settings.bullets_allowed:
new_bullet = Bullet(ai_settings, screen, ship)
bullets.add(new_bullet)
def check_keyup_events(event,ship):
"""Respond to key releases"""
if event.key == pygame.K_RIGHT:
ship.moving_right = False
elif event.key == pygame.K_LEFT:
ship.moving_left = False
def check_events(ai_settings, screen, ship, bullets):
"""Respond to keypress and mouse events"""
for event in pygame.event.get():
if event.type == pygame.QUIT:
sys.exit()
elif event.type == pygame.KEYDOWN:
check_keydown_events(event, ai_settings, screen, ship, bullets)
elif event.type == pygame.KEYUP:
check_keyup_events(event, ship)
def update_screen(ai_settings, screen, ship, aliens, bullets):
"""Update images on the screen and flip to the new screen."""
# Redraw the screen during each pass through the loop.
screen.fill(ai_settings.bg_color)
# Redraw all bullets behind ship and aliens.
for bullet in bullets.sprites():
bullet.draw_bullet()
ship.blitme()
aliens.draw(screen)
# Make the most recently drawn screen visible.
pygame.display.flip()
def update_bullets(bullets):
"""Update position of bullets and get rid of old bullets."""
# Update bullet positions.
bullets.update()
# Get rid of bullets that have disappeared.
for bullet in bullets.copy():
if bullet.rect.bottom <= 0:
bullets.remove(bullet)
def check_fleet_edges(ai_settings, aliens):
"""Respond appropriately if any aliens have reached an edge."""
for alien in aliens.sprites():
if alien.check_edges():
print(alien.name)
change_fleet_direction(ai_settings, aliens)
break
def change_fleet_direction(ai_settings, aliens):
"""Drop the entire fleet and change the fleet's direction."""
print("old direction " + str(ai_settings.fleet_direction))
for alien in aliens.sprites():
alien.rect.y += ai_settings.fleet_drop_speed
if ai_settings.fleet_direction == 1:
ai_settings.fleet_direction = -1
else:
ai_settings.fleet_direction = 1
print("new direction" + str(ai_settings.fleet_direction))
def update_aliens(ai_settings, aliens):
"""
Check if the fleet is at an edge,
and then update the positions of all aliens in the fleet.
"""
check_fleet_edges(ai_settings, aliens)
aliens.update()
主要文件alien_invasion.py
import pygame
from pygame.sprite import Group
from settings import Settings
from ship import Ship
import game_functions as gf
def run_game():
# Initialize game and create a screen object.
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)
#Make a group to store bullets in
bullets = Group()
aliens = Group()
#Create the fleet of aliens
gf.create_fleet(ai_settings, screen, ship, aliens)
# Start the main loop for the game.
while True:
gf.check_events(ai_settings, screen, ship, bullets)
ship.update()
bullets.update()
gf.update_bullets(bullets)
gf.update_aliens(ai_settings, aliens)
gf.update_screen(ai_settings, screen, ship, aliens, bullets)
run_game()
bullet.py
import pygame
from pygame.sprite import Sprite
class Bullet(Sprite):
"""A class to manage bullets fired from the ship"""
def __init__(self, ai_settings, screen, ship):
"""create a bullet object at the ship's current position"""
super().__init__()
self.screen = screen
#Create a bullet rect at (0, 0) and then set correct position
self.rect = pygame.Rect(0, 0, ai_settings.bullet_width,
ai_settings.bullet_height)
self.rect.centerx = ship.rect.centerx
self.rect.top = ship.rect.top
#Store the bullet position as a decimal value.
self.y = float(self.rect.y)
self.color = ai_settings.bullet_color
self.speed_factor = ai_settings.bullet_speed_factor
def update(self):
"""Move bullet up the scereen"""
#Update the decimal position of the bullet
self.y -= self.speed_factor
#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)
alien.py
import pygame
from pygame.sprite import Sprite
class Alien(Sprite):
"""A class to represent a single alien in the fleet"""
def __init__(self, ai_settings, screen, name):
"""Initialize the alien and set its starting position"""
super().__init__()
self.screen = screen
self.ai_settings = ai_settings
#Load the alien image and set its rect attribute.
self.image = pygame.image.load('images/alien.bmp')
self.rect = self.image.get_rect()
#Start each alien near the top left of the screen
self.rect.x = self.rect.width
self.rect.y = self.rect.height
#Store the alien's exact position
self.x = float(self.rect.x)
self.name = name
# def blitme(self):
# """Draw the alien at its current location."""
# self.screen.blit(self.image, self.rect)
#
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:
print("Right >= right screen" +' direction is' + str(self.ai_settings.fleet_direction))
return True
elif self.rect.left <= 0:
print("Left <= left")
return True
def update(self):
"""Move the alien right or left."""
self.x += (self.ai_settings.alien_speed_factor *
self.ai_settings.fleet_direction)
self.rect.x = self.x
我是pygame和sprites的新手，我不明白为什么randit会产生这样的影响。我已经在代码中放置了关键的更改即将打印语句从控制台调试它（但我不知道如果它是逻辑问题）。任何可以为它揭光的人我会非常感激。已经失去了2天的学习和编程。从Eclipse Neon在win 10上运行python 3.4非常感谢。
答案 0 :(得分：1)
在func change_fleet_direction（）中发现错误，缩进，如果block：不能在for循环中。