それっぽい機能のそろったゲームを150行以内で

それっぽい機能
* オープニング画面，ゲーム画面，終了画面，結果画面に遷移する
* ハイスコアランキングの表示
* 150行以内
* http://play-siv3d.hateblo.jp/ の書式に極力揃える
* ビジュアル的に面白く

無理やり詰め込んだ，相変わらず謎である

Main.cpp

# include <Siv3D.hpp>

void Main()
{
    enum class GameState
    {
        Opening, Game, Finish, Result
    };

    Graphics::SetBackground(Palette::Black);
    Window::SetTitle(L"十字キーで操作");
    GameState gameState = GameState::Opening;
    GameState tGameState = gameState;
    TimerMillisec timer;
    Font font(20);
    timer.start();  

    const double windowWidth = Window::Width();
    const double windowHeight = Window::Height();   
    const double playerHeight = 0.05;
    const double playerPosY = 0.1;
    const double playerSpeed = 0.01;
    const double gravity = 0.001;
    const Color col = ColorF(0.0, 1.0, 0.0);

    double playerPosX;
    double playerWidth;
    Vec2 ballPos;
    Vec2 ballVelocity;
    String scoreString;
    unsigned score;
    std::array<unsigned int, 9> scores;
    scores.fill(0);

    std::function<void()> initGame = [&]()
    {
        playerPosX = 0.5;
        playerWidth = 0.1;
        ballPos = Vec2(0.5, 0.8);
        ballVelocity = RandomVec2({-0.001, 0.001}, {-0.001, 0.001});
        scoreString.clear();
        score = 0;
    };

    std::function<void()> setScore = [&]()
    {
        score = timer.elapsed();
        auto minScore = std::min_element(scores.begin(), scores.end());

        if (*minScore < score)
        {
            *minScore = score;
            std::sort(scores.begin(), scores.end(), [&](unsigned int a, unsigned int b){return a > b; });
        }           

        for (auto it = scores.begin(); it < scores.end(); ++it)
        {
            scoreString += Format(it - scores.begin() + 1, L": ");
            scoreString += (*it == score) ? Format(L"***", score, L"***\n") : Format(*it, L'\n');
        }
    };

    std::function<Vec2(const Vec2&)> getPos = [&](const Vec2& pos){return Vec2(windowWidth * pos.x, (1.0 - pos.y) * windowHeight);};

    std::function<void()> updatePos = [&]()
    {
        ballVelocity.x = (ballPos.x < 0.0 || ballPos.x > 1.0) ? -ballVelocity.x : ballVelocity.x;
        ballVelocity.y -= gravity;
        ballPos += ballVelocity;
        playerPosX += playerSpeed * (Input::KeyRight.pressed - Input::KeyLeft.pressed);
        playerPosX = Clamp(playerPosX, 0.0, 1.0);
    };

    std::function<void()> drawBallAndPlayer = [&]()
    {
        RectF(windowWidth * playerWidth, windowHeight * playerHeight).setCenter(getPos({ playerPosX, playerPosY })).draw(col);
        for (int i = -3; i < 4; ++i)
            Circle(getPos(ballPos + static_cast<double>(i) / 3.0 * ballVelocity), 10.0).draw(col);
    };

    vector<std::function<void()>> functions = 
    {
        [&]()
        {
            font(L"ボールを落とさないようにするゲーム\nキー押すとゲーム開始").drawCenter(Window::Center(), col);

            if (Input::AnyKeyClicked())
            {
                initGame();
                gameState = GameState::Game;
            }
        }, [&]()
        {
            font(timer.elapsed()).draw({ 0.0, 0.0 }, col);

            if (RectF(playerWidth, playerHeight).setCenter(playerPosX, playerPosY).intersects(ballPos))
            {
                playerWidth *= 0.9;
                ballVelocity = Vec2(0.03 * (ballPos.x - playerPosX) / playerWidth, -ballVelocity.y);
                ballPos.y = playerPosY + playerHeight / 2.0;
            }

            updatePos();

            drawBallAndPlayer();

            if (ballPos.y < 0.0)
            {
                setScore();
                gameState = GameState::Finish;
            }
        }, [&]()
        {
            font(L"FINISH!!\nscore : ", score).drawCenter(Window::Center(), col);

            updatePos();

            if (ballPos.y < 0.0)
            {
                ballPos.y = 0.0;
                ballVelocity.x = 0.5 * ballVelocity.x;
                ballVelocity.y = -0.5 * ballVelocity.y;
            }

            drawBallAndPlayer();

            if (timer.elapsed() > 3000)
                gameState = GameState::Result;
        }, [&]()
        {
            font(scoreString).drawCenter(Window::Center(), col);

            if (Input::AnyKeyClicked())
                gameState = GameState::Opening;
        }
    };

    while (System::Update())
    {
        functions[static_cast<int>(gameState)]();

        if (tGameState != gameState)
        {
            timer.restart();

            tGameState = gameState;
        }
    }
}