函数设计 要求：对创建的void userKey()函数贴出对应代码和注释，代码为：void userKey() { t2 = GetTickCount();//获取当前系统的运行时间 if (GetAsyncKeyState(VK_UP))//向上键 { player.y -= PLAYER_SPEED; if (player.y < 0) { player.y = 0; } } else if (GetAsyncKeyState(VK_DOWN))//向下键 { player.y += PLAYER_SPEED; if (player.y > WIN_HEIGHT - PLAYER_HEIGHT) { player.y = WIN_HEIGHT - PLAYER_HEIGHT; } } else if (GetAsyncKeyState(VK_LEFT))//向左键 { player.x -= PLAYER_SPEED; if (player.x < -PLAYER_WIDTH / 2) { player.x = -PLAYER_WIDTH / 2; } } else if (GetAsyncKeyState(VK_RIGHT))//向右键 { player.x += PLAYER_SPEED; if (player.x > WIN_WIDTH - PLAYER_WIDTH / 2) { player.x = WIN_WIDTH - PLAYER_WIDTH / 2; } } if (GetAsyncKeyState(VK_SPACE) && t2 - t1 > 300) { createBullet();//创建玩家子弹 HANDLE hThread = CreateThread(NULL, 0, playMusic, NULL, NULL, NULL); t1 = t2; } }

这是一个用于处理用户键盘输入的函数，具体实现如下：

void userKey() {
    // 获取当前系统的运行时间
    t2 = GetTickCount();
    if (GetAsyncKeyState(VK_UP)) { // 向上键
        player.y -= PLAYER_SPEED;
        if (player.y < 0) {
            player.y = 0;
        }
    } else if (GetAsyncKeyState(VK_DOWN)) { // 向下键
        player.y += PLAYER_SPEED;
        if (player.y > WIN_HEIGHT - PLAYER_HEIGHT) {
            player.y = WIN_HEIGHT - PLAYER_HEIGHT;
        }
    } else if (GetAsyncKeyState(VK_LEFT)) { // 向左键
        player.x -= PLAYER_SPEED;
        if (player.x < -PLAYER_WIDTH / 2) {
            player.x = -PLAYER_WIDTH / 2;
        }
    } else if (GetAsyncKeyState(VK_RIGHT)) { // 向右键
        player.x += PLAYER_SPEED;
        if (player.x > WIN_WIDTH - PLAYER_WIDTH / 2) {
            player.x = WIN_WIDTH - PLAYER_WIDTH / 2;
        }
    }
    if (GetAsyncKeyState(VK_SPACE) && t2 - t1 > 300) { // 空格键
        createBullet(); // 创建玩家子弹
        HANDLE hThread = CreateThread(NULL, 0, playMusic, NULL, NULL, NULL); // 创建线程播放音效
        t1 = t2;
    }
}

该函数的作用是监听用户在键盘上的操作，根据用户的输入来更新玩家的位置，并在用户按下空格键时创建玩家子弹并播放音效。其中 `GetAsyncKeyState()` 函数用于检测对应的按键是否被按下，`createBullet()` 函数用于创建玩家子弹，`CreateThread()` 函数用于创建一个新的线程来播放音效。