音声合成

# include <Siv3D.hpp>

bool Synthesize(const ParsedExpression& exp, Wave& wave)
{
    if (!exp.isValid() || !exp.evaluateOpt({ { L"x", 0 },{ L"t", 0 },{ L"Pi", Pi },{ L"TwoPi", TwoPi } }))
    {
        return false;
    }

    for (size_t i = 0; i < wave.lengthSample; ++i)
    {
        const double t = i / 44100.0;
        wave[i] = Waving::DoubleToSample(exp.evaluateOpt(
        { { L"x", 440.0 * t * TwoPi },{ L"t", t }, { L"Pi", Pi },{ L"TwoPi", TwoPi } }).value_or(0.0));
    }

    return true;
}

void Main()
{
    const String defaultExpression = L"sin(x)";
    ParsedExpression f(defaultExpression);

    GUI gui(GUIStyle::Default);
    gui.addln(L"exp", GUITextArea::Create(2, 32));
    gui.add(L"play", GUIButton::Create(L"再生"));
    gui.add(L"scale", GUISlider::Create(1, 10.0, 1, 300));
    gui.textArea(L"exp").setText(defaultExpression);

    Wave wave(3.0s, [](double t){ return Sin(440 * t * TwoPi); });
    Sound sound(wave);
    sound.setVolume(0.3);

    LineString lines(6400, Vec2(0,0));

    while (System::Update())
    {
        if (gui.textArea(L"exp").hasChanged)
        {
            if (Synthesize(ParsedExpression(gui.textArea(L"exp").text), wave))
            {
                sound.fill(wave);
                gui.textArea(L"exp").style.color = Palette::Black;
            }
            else
            {
                gui.textArea(L"exp").style.color = Palette::Red;
            }
        }

        gui.button(L"play").enabled = !sound.isPlaying();

        if (gui.button(L"play").pushed)
        {
            sound.play();
        }

        const double s = gui.slider(L"scale").value;
        const int32 count = static_cast<int32>(640 * s);

        for (size_t i = 0; i < count; ++i)
        {
            lines.point(i).set(i * (1.0 / s), 290 + wave[static_cast<int32>(i * s)].left / 200);
        }

        Line(0, 290, 640, 290).draw(Color(0, 255, 0));

        lines.substr(0, count).draw(2);
    }
}