MIDIビジュアライザー

# include <Siv3D.hpp>

struct Note
{
    uint32 ch;
    uint32 noteNumber;
    int32 startMillisec;
    int32 lengthMillisec;

    double alpha;
    bool barPassed;
    bool onBar;
};

void Main()
{
    Window::Resize(1280, 720);

    Midi::Open(Dialog::GetOpenMidi().value());
    const auto score = Midi::GetScore();
    Array<Note> noteRects;
    uint32 minPitch = 127, maxPitch = 0;

    for (auto ch : step(static_cast<uint32>(score.size())))
    {
        for (const auto& note : score[ch])
        {
            noteRects.push_back({ ch, note.noteNumber, note.startMillisec, note.lengthMillisec, 1.0, false, false });
            minPitch = Min(minPitch, note.noteNumber);
            maxPitch = Max(maxPitch, note.noteNumber);
        }
    }

    while (System::Update())
    {
        const double scale = 0.2;
        const int32 offset = 160;
        const int32 offsetMillisec = static_cast<int32>(offset / scale);
        const RectF line(offset - 1, 0, 6, Window::Height());
        const double blockHeight = static_cast<double>(Window::Height()) / (maxPitch - minPitch + 1);

        if (!Midi::IsPlaying())
        {
            for (auto& note : noteRects)
            {
                note.alpha = 1.0;
                note.barPassed = false;
                note.onBar = false;
            }
        }

        if (Input::MouseL.clicked)
        {
            Midi::Play();
        }

        const double pos = (Midi::GetPosSec() * 1000 - 100)* scale;
        const int32 bar = static_cast<int32>(Midi::GetPosSec() * 1000 - 100);
        const int32 left = bar - offsetMillisec;
        const int32 right = static_cast<int32>(left + Window::Width() / scale);

        Array<size_t> visibleNoteIndices;
        size_t index = 0;

        for (auto& note : noteRects)
        {
            if (right < note.startMillisec || (note.startMillisec + note.lengthMillisec) < left)
            {
                ++index;
                continue;
            }

            note.onBar = note.startMillisec <= bar && bar <= (note.startMillisec + note.lengthMillisec);
            note.barPassed = note.startMillisec <= bar;

            if (note.barPassed)
            {
                note.alpha *= note.onBar ? 0.98 : 0.85;
            }

            visibleNoteIndices.push_back(index++);
        }

        Graphics2D::SetBlendState(BlendState::Default);

        for (auto& i : visibleNoteIndices)
        {
            const auto& note = noteRects[i];

            if (!note.barPassed)
            {
                const RectF r(note.startMillisec * scale + offset - pos, (maxPitch - note.noteNumber) * blockHeight, note.lengthMillisec * scale, blockHeight);
                RoundRect(r, 4).draw(ColorF(0.2, 0.25, 0.3));
            }
        }

        Graphics2D::SetBlendState(BlendState::Additive);

        for (auto& i : visibleNoteIndices)
        {
            const auto& note = noteRects[i];

            if (note.barPassed)
            {
                const RectF r(note.startMillisec * scale + offset - pos, (maxPitch - note.noteNumber) * blockHeight, note.lengthMillisec * scale, blockHeight);
                RoundRect(r, 5).drawShadow({ 0, 0 }, 12 + note.alpha * 8, 2 + note.alpha * 8, HSV(30 + note.ch * 100, 0.5, 1).toColorF(note.alpha*0.4));
            }
        }

        for (auto& i : visibleNoteIndices)
        {
            const auto& note = noteRects[i];

            if (note.barPassed)
            {
                const RectF r(note.startMillisec * scale + offset - pos, (maxPitch - note.noteNumber) * blockHeight, note.lengthMillisec * scale, blockHeight);
                RoundRect(r, 4).draw(HSV(30 + note.ch * 100, 1, 1).toColorF(note.alpha));
            }
        }

        line.draw(Alpha(20));
    }
}