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:
        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 check_keyup_events(event,ship):
    # 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 check_events(ai_settings,screen,stats, play_button, ship, bullets):
    # 响应事件
    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):
    """"单击Play开始新游戏"""
    if play_button.rect.collidepoint(mouse_x,mouse_y):
        stats.game_active = True

def fire_bullet(ai_settings,screen,ship,bullets):               
    # 创建一颗子弹
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings,screen,ship)
        bullets.add(new_bullet)


def update_screen(ai_settings, screen, stats, ship, aliens, bullets, play_button):
    # 更新屏幕
    # 重绘背景色
    screen.fill(ai_settings.bg_color)
    # 重绘子弹
    for bullet in bullets.sprites():
        bullet.draw_bullet()
    ship.blitme()
    aliens.draw(screen)
    if not stats.game_active:
        play_button.draw_button()
    # 显示
    pygame.display.flip()


def update_bullets(ai_settings, screen, ship, aliens, 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)
    check_bullet_alien_collisions(ai_settings, screen, ship, aliens, bullets)


def check_bullet_alien_collisions(ai_settings, screen, ship, aliens, bullets):
    # 检查是否有子弹击中外星人，并删除相应的子弹和外星人
    collisios = pygame.sprite.groupcollide(bullets, aliens, True, True)
    if len(aliens) == 0:
        # 删除现有的子弹并新建一群外星人
        bullets.empty()
        create_fleet(ai_settings, screen, ship, aliens)


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-(3 * alien_height) - ship_height)
    number_rows = int(available_space_y / (2 * alien_height))
    return number_rows


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 create_alien(ai_settings, screen, aliens, alien_number, row_number):
    # 创建一个外星人并将其加入当前行
    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外星人
    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 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减一
        stats.ships_left -= 1

        # 清空外星人和子弹
        aliens.empty()
        bullets.empty()

        # 创建一群新外星人和飞船
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()

        # 暂停
        sleep(0.5)
    else:
        stats.game_active = False


def check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets):
    """"检查外星人是否到达底部"""
    # screen_rect = screen.get_rect() 我修改为到飞船顶部就算到达底部
    for alien in aliens.sprites():
        if alien.rect.bottom >= ship.rect.top:
            # 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):
    """"更新所有外星人位置"""
    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)

    # 检测外星人是否到达底部
    check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets)


def check_fleet_edges(ai_settings, aliens):
    """"到达边缘时才去相应措施"""
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings, aliens)
            break


def change_fleet_direction(ai_settings, aliens):
    """"将整群外星人下移，并改变方向"""
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1