函数设计 要求：对创建的void createEnemy()函数贴出对应代码和注释，代码为：void createEnemy() { t4 = GetTickCount();//获取当前系统的运行时间 if (t4 - t3 > 2000) { for (int i = 0; i < ENEMY_NUM; i++) { if (!enemy[i].flag)//若敌机未摧毁 { enemy[i].flag = true; int result = rand() % 10; if (result == 0) { enemy[i].Myunion.type = BIG; enemy[i].hp = BIG_HP;//大型敌机 enemy[i].x = rand() % (WIN_WIDTH - 100); enemy[i].y = -153; } else if (result == 1 || result == 2) { enemy[i].Myunion.type = MEDIUM; enemy[i].hp = MEDIUM_HP;//中型敌机 enemy[i].x = rand() % (WIN_WIDTH - 69); enemy[i].y = -99; } else { enemy[i].Myunion.type = SAMLL; enemy[i].hp = SMALL_HP;//小型敌机 enemy[i].x = rand() % (WIN_WIDTH - 57); enemy[i].y = -43; } break; } } t3 = t4; } }

这是一个创建敌机的函数，主要功能是在游戏画面中生成敌机。以下是对代码的注释：

void createEnemy() {
    t4 = GetTickCount(); // 获取当前系统的运行时间

    if (t4 - t3 > 2000) { // 如果时间超过2秒

        for (int i = 0; i < ENEMY_NUM; i++) { // 循环ENEMY_NUM次，生成敌机

            if (!enemy[i].flag) { // 若敌机未摧毁

                enemy[i].flag = true; // 将敌机标记为已生成

                int result = rand() % 10; // 生成随机数

                if (result == 0) { // 若随机数为0，生成大型敌机

                    enemy[i].Myunion.type = BIG;
                    enemy[i].hp = BIG_HP;
                    enemy[i].x = rand() % (WIN_WIDTH - 100);
                    enemy[i].y = -153;

                } else if (result == 1 || result == 2) { // 若随机数为1或2，生成中型敌机

                    enemy[i].Myunion.type = MEDIUM;
                    enemy[i].hp = MEDIUM_HP;
                    enemy[i].x = rand() % (WIN_WIDTH - 69);
                    enemy[i].y = -99;

                } else { // 若随机数为其他，生成小型敌机

                    enemy[i].Myunion.type = SAMLL;
                    enemy[i].hp = SMALL_HP;
                    enemy[i].x = rand() % (WIN_WIDTH - 57);
                    enemy[i].y = -43;

                }

                break; // 跳出循环，生成一个敌机即可

            }

        }

        t3 = t4; // 将上次生成敌机的时间更新为当前时间

    }
}