game_functions.py

import sys
from time import sleep

import pygame
from bullet import Bullet
from alien import Alien

def check_keydown_events(event, ai_settings, screen, stats, sb, ship, aliens,
        bullets):
    """响应按键"""
    if event.key in (pygame.K_RIGHT, pygame.K_d):
        # 向左移动飞船
        ship.moving_right = True
    elif event.key in (pygame.K_LEFT, pygame.K_a):
        # 向右移动飞船
        ship.moving_left = True
    elif event.key == pygame.K_SPACE and stats.game_active:
        # 创建一个子弹，并将其加入到编组bullets中
        fire_bullet(ai_settings, screen, ship, bullets)
    elif event.key == pygame.K_p:
        if not stats.game_active:
            start_game(ai_settings, screen, stats, sb, ship, aliens, bullets)
    elif event.key == pygame.K_q:
        sys.exit()

def fire_bullet(ai_settings, screen, ship, bullets):
    """如果还没有达到极限就还发射一颗子弹"""
    # 创建新子弹并将其加入到编组bullets中
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)

def check_keyup_events(event, ship):
    """响应松开"""
    if event.key in (pygame.K_RIGHT, pygame.K_d):
        ship.moving_right = False
    elif event.key in (pygame.K_LEFT, pygame.K_a):
        ship.moving_left = False

def check_events(ai_settings, screen, stats, sb, play_button, ship, aliens,
        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, stats, sb, ship, aliens,
                    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(ai_settings, screen, stats, sb, play_button, ship,
                    aliens, bullets, mouse_x, mouse_y)

def check_play_button(ai_settings, screen, stats, sb, play_button, ship, aliens,
        bullets, mouse_x, mouse_y):
    """在玩家单击Play按钮的时候开始游戏"""
    button_clicked = play_button.rect.collidepoint(mouse_x, mouse_y)
    if button_clicked and play_button.rect.collidepoint(mouse_x, mouse_y):
        start_game(ai_settings, screen, stats, sb, ship, aliens, bullets)

def start_game(ai_settings, screen, stats, sb, ship, aliens, bullets):
    """用于游戏开始时的一些初始化"""
    # 重置游戏的设置
    ai_settings.initialize_dynamic_settings()

    # 隐藏光标
    pygame.mouse.set_visible(False)

    # 重置游戏统计信息
    stats.reset_stats()
    stats.game_active = True

    # 重置记分牌图像
    sb.prep_score()
    sb.prep_high_score()
    sb.prep_level()

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

    # 创建一群新的外星人，并将其居中
    create_fleet(ai_settings, screen, ship, aliens)
    ship.center_ship()

def update_screen(ai_settings, screen, stats, sb, 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)
    for bullet in bullets.sprites():
        bullet.draw_bullet()
    ship.blitme()
    aliens.draw(screen)

    # 显示得分
    sb.show_score()

    # 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_botton()

    # 让最近绘制的屏幕可见
    pygame.display.flip()

def update_bullets(ai_settings, screen, stats, sb, ship, aliens, bullets):
    """更新子弹的位置，并删除已经消失的子弹"""
    # 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, stats, sb, ship,
            aliens, bullets)

def check_high_score(stats, sb):
    """检查是否诞生了新的最高分"""
    if stats.score > stats.high_score:
        stats.high_score = stats.score
        sb.prep_high_score()

def check_bullet_alien_collisions(ai_settings, screen, stats, sb, ship,
        aliens, bullets):
    """响应子弹和外星人的碰撞"""
    # 删除发生碰撞的子弹和外星人
    collisions = pygame.sprite.groupcollide(bullets, aliens, False, True)

    # 发生碰撞的时候更新得分
    if collisions:
        for aliens in collisions.values():
            stats.score += ai_settings.alien_points * len(aliens)
            sb.prep_score()
        check_high_score(stats, sb)

    if len(aliens) == 0:
        # 删除现有的子弹并新建一群外星人
        bullets.empty()
        ai_settings.increase_speed()

        # 提高等级
        stats.level += 1
        sb.prep_level()
        create_fleet(ai_settings, screen, ship, aliens)

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):
    """计算屏幕可以容纳多少行外星人"""
    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):
    """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，并计算一行可容纳多少个外星人
    # 外星人的间距为外星人的宽度
    alien = Alien(ai_settings, screen)
    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)

    # 创建第一行外星人
    for row_number in range(number_rows):
        for alien_number in range(number_aliens_x):
            create_alien(ai_settings, screen, aliens, alien_number,
                    row_number)

def check_fleet_edges(ai_settings, aliens):
    """有外星人到达边界时应采取措施"""
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings, aliens)
            break

def change_fleet_direction(ai_settings, aliens):
    """将外星人下移，并改变他们的方向"""
    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_lift将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，并将飞船放到屏幕底端中央
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()

        # 休息一会
        sleep(0.5)
    else:
        stats.gate_active = False
        pygame.mouse.set_visible(False)


def check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets):
    """检查是否有外星人到达了屏幕的底端"""
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            # 像飞船被撞到一样的处理
            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，并更新所有的外星人的位置
    """
    check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets)
    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)