game_functions.py

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


def check_events(ai_settings, screen, ship, bullets, play_button, stats, aliens):
    """获取鼠标键盘事件"""
    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(ship, event)
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x, mouse_y = pygame.mouse.get_pos()
            check_play_button(play_button, mouse_x, mouse_y, stats, aliens, bullets, ai_settings, screen, ship)


def update_screen(ai_setting, screen, ship, aliens, bullets, play_button, stats, sb):
    """更新屏幕上的图形，并切换到新屏幕上"""
    # 每次循环都重新绘制图像
    screen.fill(ai_setting.bg_color)

    # 在飞船和外星人后面绘制所有子弹
    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_button()

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


def check_keydown_events(event, ai_settings, screen, ship, bullets):
    """响应按下"""
    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:
        # 发射子弹
        fire_bullet(ai_settings, screen, ship, bullets)
    elif event.key == pygame.K_q:
        sys.exit()


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


def update_bullets(bullets, aliens, ai_settings, screen, ship, stats, sb):
    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_collide(ai_settings, screen, ship, aliens, bullets, stats, sb)


def check_bullet_alien_collide(ai_settings, screen, ship, aliens, bullets, stats, sb):
    # 检查是否有子弹击中了外星人，击中了则将子弹和外星人都删除
    collisions = pygame.sprite.groupcollide(bullets, aliens, False, True)

    if collisions:
        for aliens in collisions.values():
            stats.score += ai_settings.alien_points * len(aliens)
            sb.prep_score()
        check_high_score(stats, sb)

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


def fire_bullet(ai_settings, screen, ship, bullets):
    # 创建一颗子弹,并将其添加的编组bullets中去
    if len(bullets) < ai_settings.bullet_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)


def get_alien_count_y(ai_settings, ship_height, alien_height):
    available_space_y = ai_settings.screen_height - 3 * alien_height - ship_height
    return int(available_space_y / (2 * alien_height))


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
    # 确定外星人间距
    alien = Alien(ai_settings, screen)

    alien_count_x = get_alien_count_x(alien.rect.width, ai_settings)
    alien_count_y = get_alien_count_y(ai_settings, ship.rect.height, alien.rect.height)

    # 创建一行外星人
    for row_number in range(alien_count_y):
        for alien_number in range(alien_count_x):
            # 创建一个外星人，并加入当前行
            create_alien(ai_settings, screen, alien_number, aliens, row_number)


def get_alien_count_x(alien_width, ai_settings):
    """计算每行可容纳多少个外星人"""
    available_space_x = ai_settings.screen_width - 2 * alien_width
    return int(available_space_x / (2 * alien_width))


def create_alien(ai_settings, screen, alien_number, aliens, row_number):
    """创建一个外星人并放置到当前行"""
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    alien.x = alien_width + 2 * alien_width * alien_number
    alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_number
    alien.rect.x = alien.x
    aliens.add(alien)


def ship_hit(ai_settings, stats, screen, aliens, ship, 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()

        # 暂停
        sleep(0.5)
    else:
        stats.game_active = False
        pygame.mouse.set_visible(True)


def update_aliens(ai_settings, stats, screen, aliens, ship, bullets):
    """检查是否有外星人到达边缘，并更新每一个外星人的位置"""
    check_fleet_edges(ai_settings, aliens)
    aliens.update()

    # 检测飞船和外星人之间的碰撞
    if pygame.sprite.spritecollideany(ship, aliens):
        ship_hit(ai_settings, stats, screen, aliens, ship, bullets)

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


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


def change_fleet_direction(ai_settings, aliens):
    """外星人群向下移，并改变的方向"""
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1


def check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets):
    """ 检查是否有外星人到达了屏幕底端 """
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            # 像飞船被撞到一样进行处理
            ship_hit(ai_settings, stats, screen, ship, aliens, bullets)
            break


def check_play_button(play_button, mouse_x, mouse_y, stats, aliens, bullets, ai_settings, screen, ship):
    """在单击play按钮时开始游戏"""
    if play_button.rect.collidepoint(mouse_x, mouse_y) and not stats.game_active:
        # 隐藏光标
        pygame.mouse.set_visible(False)

        # 初始化数据
        ai_settings.initialize_dynamic_settings()

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

        # 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,并让飞船居中
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()


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