请用c++写出一个飞机大战的游戏

这里给出一个简单的飞机大战的游戏，使用C++语言和SFML库实现。游戏规则是：玩家控制一架飞机，消灭敌机并获得分数，同时要躲避敌机的攻击。游戏分为两个场景：开始场景和游戏场景。

1. 开始场景

开始场景显示游戏标题，同时提示玩家按下空格键开始游戏。

2. 游戏场景

游戏场景显示玩家飞机、敌机和子弹，玩家可以通过键盘控制飞机的移动和发射子弹。敌机会不断向玩家飞机发射子弹，玩家需要躲避敌机的攻击，并且消灭敌机以获得分数。游戏场景还包括计分板，显示玩家的得分和剩余生命值。

下面是主要的游戏代码实现：

#include <SFML/Graphics.hpp>
#include <iostream>
#include <vector>
#include <cstdlib>
#include <ctime>

using namespace sf;

// 定义常量
const int WINDOW_WIDTH = 800;
const int WINDOW_HEIGHT = 600;
const float PLAYER_SPEED = 5.0f;
const float BULLET_SPEED = 10.0f;
const float ENEMY_SPEED = 3.0f;
const int ENEMY_SCORE = 10;
const int PLAYER_LIFE = 3;

// 定义玩家飞机
class Player {
public:
    Player(Texture& texture, Vector2f position) {
        m_sprite.setTexture(texture);
        m_sprite.setPosition(position);
        m_life = PLAYER_LIFE;
    }

    void update() {
        if (Keyboard::isKeyPressed(Keyboard::Left)) {
            m_sprite.move(-PLAYER_SPEED, 0);
        }
        if (Keyboard::isKeyPressed(Keyboard::Right)) {
            m_sprite.move(PLAYER_SPEED, 0);
        }
        if (Keyboard::isKeyPressed(Keyboard::Up)) {
            m_sprite.move(0, -PLAYER_SPEED);
        }
        if (Keyboard::isKeyPressed(Keyboard::Down)) {
            m_sprite.move(0, PLAYER_SPEED);
        }
    }

    void draw(RenderWindow& window) {
        window.draw(m_sprite);
    }

    Vector2f getPosition() {
        return m_sprite.getPosition();
    }

    void setLife(int life) {
        m_life = life;
    }

    int getLife() {
        return m_life;
    }

private:
    Sprite m_sprite;
    int m_life;
};

// 定义子弹
class Bullet {
public:
    Bullet(Texture& texture, Vector2f position) {
        m_sprite.setTexture(texture);
        m_sprite.setPosition(position);
    }

    void update() {
        m_sprite.move(0, -BULLET_SPEED);
    }

    void draw(RenderWindow& window) {
        window.draw(m_sprite);
    }

    Vector2f getPosition() {
        return m_sprite.getPosition();
    }

private:
    Sprite m_sprite;
};

// 定义敌机
class Enemy {
public:
    Enemy(Texture& texture, Vector2f position) {
        m_sprite.setTexture(texture);
        m_sprite.setPosition(position);
    }

    void update() {
        m_sprite.move(0, ENEMY_SPEED);
    }

    void draw(RenderWindow& window) {
        window.draw(m_sprite);
    }

    Vector2f getPosition() {
        return m_sprite.getPosition();
    }

    void setScore(int score) {
        m_score = score;
    }

    int getScore() {
        return m_score;
    }

private:
    Sprite m_sprite;
    int m_score;
};

int main() {
    // 创建窗口
    RenderWindow window(VideoMode(WINDOW_WIDTH, WINDOW_HEIGHT), "飞机大战");

    // 加载纹理
    Texture playerTexture, bulletTexture, enemyTexture;
    playerTexture.loadFromFile("player.png");
    bulletTexture.loadFromFile("bullet.png");
    enemyTexture.loadFromFile("enemy.png");

    // 创建玩家飞机
    Player player(playerTexture, Vector2f(WINDOW_WIDTH / 2, WINDOW_HEIGHT - 100));

    // 创建子弹和敌机数组
    std::vector<Bullet> bullets;
    std::vector<Enemy> enemies;

    // 创建字体和文本
    Font font;
    font.loadFromFile("arial.ttf");
    Text scoreText, lifeText;
    scoreText.setFont(font);
    scoreText.setCharacterSize(24);
    scoreText.setPosition(10, 10);
    lifeText.setFont(font);
    lifeText.setCharacterSize(24);
    lifeText.setPosition(WINDOW_WIDTH - 100, 10);

    // 设置随机种子
    srand(time(NULL));

    // 游戏循环
    int score = 0;
    int life = PLAYER_LIFE;
    while (window.isOpen()) {
        // 处理事件
        Event event;
        while (window.pollEvent(event)) {
            if (event.type == Event::Closed) {
                window.close();
            }

            // 玩家发射子弹
            if (event.type == Event::KeyPressed && event.key.code == Keyboard::Space) {
                bullets.push_back(Bullet(bulletTexture, player.getPosition()));
            }
        }

        // 更新玩家飞机
        player.update();

        // 更新子弹和敌机
        for (int i = 0; i < bullets.size(); i++) {
            bullets[i].update();
            if (bullets[i].getPosition().y < 0) {
                bullets.erase(bullets.begin() + i);
            }
        }

        for (int i = 0; i < enemies.size(); i++) {
            enemies[i].update();
            if (enemies[i].getPosition().y > WINDOW_HEIGHT) {
                enemies.erase(enemies.begin() + i);
            }
        }

        // 生成敌机
        if (rand() % 100 < 5) {
            enemies.push_back(Enemy(enemyTexture, Vector2f(rand() % WINDOW_WIDTH, 0)));
        }

        // 处理碰撞
        for (int i = 0; i < bullets.size(); i++) {
            for (int j = 0; j < enemies.size(); j++) {
                if (bullets[i].getPosition().x > enemies[j].getPosition().x &&
                    bullets[i].getPosition().x < enemies[j].getPosition().x + enemyTexture.getSize().x &&
                    bullets[i].getPosition().y > enemies[j].getPosition().y &&
                    bullets[i].getPosition().y < enemies[j].getPosition().y + enemyTexture.getSize().y) {
                    score += enemies[j].getScore();
                    bullets.erase(bullets.begin() + i);
                    enemies.erase(enemies.begin() + j);
                }
            }
        }

        for (int i = 0; i < enemies.size(); i++) {
            if (enemies[i].getPosition().x > player.getPosition().x &&
                enemies[i].getPosition().x < player.getPosition().x + playerTexture.getSize().x &&
                enemies[i].getPosition().y > player.getPosition().y &&
                enemies[i].getPosition().y < player.getPosition().y + playerTexture.getSize().y) {
                life--;
                enemies.erase(enemies.begin() + i);
                if (life == 0) {
                    window.close();
                }
            }
        }

        // 绘制场景
        window.clear(Color::White);

        player.draw(window);

        for (int i = 0; i < bullets.size(); i++) {
            bullets[i].draw(window);
        }

        for (int i = 0; i < enemies.size(); i++) {
            enemies[i].draw(window);
        }

        scoreText.setString("得分: " + std::to_string(score));
        window.draw(scoreText);

        lifeText.setString("生命: " + std::to_string(life));
        window.draw(lifeText);

        window.display();
    }

    return 0;
}

这个游戏只是一个简单的实现，还有很多可以改进和优化的地方。