game_functions.py

import sys

import pygame
from bullet import Bullet
from alien import Alien
from time import sleep


def check_keydown_events(event, ai_settings, screen, ship, bullets):
    '''响应按键'''
    if event.key == pygame.K_RIGHT:
        # 向右移动飞船
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        # 向左移动
        ship.moving_left = True
    elif event.key == pygame.K_UP:
        # 向前移动
        ship.moving_up = True
    elif event.key == pygame.K_DOWN:
        # 向后移动
        ship.moving_down = True
    elif event.key == pygame.K_SPACE:
        fire_bullet(ai_settings, screen, ship, bullets)
    elif event.key == pygame.K_q:
        sys.exit()


def check_keyup_events(event, ship):
    '''响应松开'''
    if event.key == pygame.K_RIGHT:
        # 停止向右移动飞船
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        # 停止向左移动
        ship.moving_left = False
    elif event.key == pygame.K_UP:
        # 停止向左移动
        ship.moving_up = False
    elif event.key == pygame.K_DOWN:
        # 停止向左移动
        ship.moving_down = False


def check_events(ai_settings, screen, stats, play_button, ship, bullets):
    '''响应按键和鼠标事件'''
    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)
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x, mouse_y = pygame.mouse.get_pos()
            check_play_button(stats, play_button, mouse_x, mouse_y)


def check_play_button(stats, play_button, mouse_x, mouse_y):
    '''在玩家单机play按钮时开始游戏'''
    if play_button.rect.collidepoint(mouse_x, mouse_y):
        stats.game_active = True


def update_screen(ai_settings, screen, stats, ship, aliens, bullets, play_button):
    '''更新屏幕上的图像，并切换到新屏幕'''
    # 每次循环时都重绘屏幕
    screen.fill(ai_settings.bg_color)
    # 在飞船和外星人后面重新绘制所有子弹
    for bullets in bullets.sprites():
        # 先创建出对象，在这里为对象赋颜色，尺寸等信息
        bullets.draw_bullet()
    ship.blitme()
    # 绘制外星人
    aliens.draw(screen)
    # 如果游戏处于非活动状态，就绘制Play按钮
    if not stats.game_active:
        play_button.draw_button()
    # 让最近绘制的屏幕可见
    pygame.display.flip()


def update_bullets(ai_settings, screen, ship, aliens, bullets):
    '''更新子弹的位置，并删除已消失的子弹'''
    # 更新子弹的位置
    bullets.update()

    # 删除已消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)
    check_bullet_alien_collisions(ai_settings, screen, ship, aliens, bullets)


def check_bullet_alien_collisions(ai_settings, screen, ship, aliens, bullets):
    ''' 相应子弹和外星人的碰撞'''
    # 删除发生碰撞的子弹和外星人
    '''
        sprite.groupcollide() 将每颗子弹的rect同每个外星人的rect进行比较,
        并返回一个字典，其中包含发生了碰撞的子弹和外星人。键是子弹，值是外星人
    
    '''
    collisions = pygame.sprite.groupcollide(bullets, aliens, True, True)

    if len(aliens) == 0:
        # 删除现有的所有子弹，并创建一个新的外星人群
        bullets.empty()
        create_fleet(ai_settings, screen, ship, aliens)


def fire_bullet(ai_settings, screen, ship, bullets):
    if len(bullets) < ai_settings.bullet_allowed:
        # 空格键 创建一颗子弹，并将其加入到编组bullets中
        now_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(now_bullet)


def get_number_aliens_x(ai_settings, alien_width):
    '''计算每行可容纳多少个外星人'''
    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):
    '''计算屏幕可容纳多少行外星人'''
    available_space_y = ai_settings.screen_height - 2 * 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):
    '''创建一个外星人，并将其放在当前行'''
    alien = Alien(ai_settings, screen)
    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 create_fleet(ai_settings, screen, ship, aliens):
    '''创建外星人群'''
    # 创建一个外星人，并计算一行和容纳多少外星人
    # 外星人间距为外星人宽度
    alien = Alien(ai_settings, screen)
    number_aliens_x = get_number_aliens_x(ai_settings, alien.rect.width)
    row_numbers = get_number_rows(ai_settings, ship.rect.height, alien.rect.height)

    # 创建外星人群
    for row_number in range(row_numbers):
        # 创建第一排外星人
        for alien_number in range(number_aliens_x):
            # 创建一个外星人并将其加入当前行
            create_alien(ai_settings, screen, aliens, alien_number, row_number)


def check_fleet_edges(ai_settings, aliens):
    '''有外星人到达边缘时采取想应的措施'''
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings, aliens)
            break


def change_fleet_direction(ai_settings, aliens):
    '''将整个外星人下移，并改变它们的方向'''
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1


def ship_hit(ai_settings, stats, screen, ship, aliens, bullets):
    '''响应被外星人撞到的飞船'''
    if stats.ships_left > 0:
        # 将ships_left减1
        stats.ships_left -= 1

        # 清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()

        # 创建一群新的外星人，并将飞船放到屏幕低端中央
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()
        ship.blitme()

        # 暂停
        sleep(0.5)

    else:
        stats.game_active = False


def check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets):
    '''检查是否有外星人到达屏幕低端'''
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            # 像飞船被撞到一样处理
            ship_hit(ai_settings, stats, screen, ship, aliens, bullets)
            break


def update_aliens(ai_settings, stats, screen, ship, aliens, bullets):
    '''检查是否有外星人位于屏幕边缘，并更新整群外星人的位置'''
    check_fleet_edges(ai_settings, aliens)
    aliens.update()

    # 检测外星人和飞船之间的碰撞
    if pygame.sprite.spritecollideany(ship, aliens):
        ship_hit(ai_settings, stats, screen, ship, aliens, bullets)

    # 检查是否有外星人到达屏幕低端
    check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets)