Playing live

// Visuals in time with the music -- no math with Millis() or frame counts.
//
//   Beat()          where the music is, in beats (2.5 = halfway through beat 3)
//   Phase(n)        0 -> 1 ramp every n beats (0 = right on the beat)
//   Pulse(n)        1 on the beat, fading out before the next one
//   OnBeat(n)       true on the one frame a new beat (or every n beats) starts
//   BeatTween(a, b, Ease.OutBack)   a -> b, landing exactly on the next beat
//
// While sound plays they follow what you HEAR; the loops' first downbeat is
// beat 0 of a bar. Change Bpm and press Hot Reload: everything keeps up.
public class MySketch : Sketch
{
    private int _palette;
    private readonly float[] _hues = { 200, 330, 40, 160 };

    public override void Setup()
    {
        Size(720, 480);
        Bpm = 110;
    }

    [LiveLoop]
    async Task Drums()
    {
        for (int i = 0; i < 4; i++)
        {
Sample("kick");
if (i % 2 == 1) Sample("snare", amp: 0.7);
await Sleep(0.5);
Sample("hat", amp: 0.4);
await Sleep(0.5);
        }
    }

    [LiveLoop]
    async Task Bass()
    {
        foreach (var note in new[] { "E2", "E2", "G2", "A2" })
        {
UseSynth(Synth.Saw);
Play(note, amp: 0.4, release: 0.5, cutoff: 75);
await Sleep(1);
        }
    }

    public override void Draw()
    {
        if (OnBeat(4))
_palette = (_palette + 1) % _hues.Length;  // a new color every bar
        float hue = _hues[_palette];

        Background(12, 12, 18);

        // 1. The ring throbs on every beat.
        float throb = Pulse(1, sharpness: 5);
        NoFill();
        StrokeWeight(6 + throb * 10);
        StrokeHSB(hue, 70, 100);
        Circle(180, 200, 140 + throb * 60);

        // 2. Blocks slide to a new spot on every beat, landing on the next one.
        NoStroke();
        for (int i = 0; i < 4; i++)
        {
int step = (int)Beat() + i;
float from = 360 + (step % 4) * 80;
float to = 360 + ((step + 1) % 4) * 80;
float x = BeatTween(from, to, Ease.OutBack);
FillHSB((hue + i * 30) % 360, 60, 95);
Rect(x, 90 + i * 60, 50, 40);
        }

        // 3. A 16-step sequencer row: the cursor is Beat() in sixteenths.
        int sixteenth = (int)(Beat() * 4) % 16;
        for (int i = 0; i < 16; i++)
        {
bool on = i == sixteenth;
if (on) FillHSB(hue, 50, 100); else Fill(255, i % 4 == 0 ? 70 : 35);
Rect(40 + i * 40, 400, 32, on ? 40 : 24);
        }

        // 4. Bars and beats as text.
        Fill(255, 200);
        TextSize(14);
        Text($"bar {(int)Bar() + 1}   beat {(int)Beat() % 4 + 1}   {Bpm:0} BPM", 40, 380);
    }
}

// MIDI learn: play this flower with a MIDI controller.
//
// 1. Click MIDI in the [Tweak] panel (top right): it lights up.
// 2. Touch a slider, then turn a knob or move a fader: they're connected.
// 3. Do the same with as many sliders as you like, then click MIDI again.
//
// Connections last the whole session (Run and Hot Reload keep them). To make
// one permanent, write it in Setup(): MapMidi("petals", 21);
// Pads and keys fire bursts (OnMidi), sized by velocity; the pitch-bend wheel
// twists the whole flower. No controller? Keys 1-8 fake pad hits.
public class MySketch : Sketch
{
    [Tweak(3, 24)] int petals = 9;
    [Tweak(30, 260)] float radius = 150;
    [Tweak(0, 3)] float spin = 0.5f;
    [Tweak(0, 360)] float hue = 200;
    [Tweak(0, 1)] float wobble = 0.35f;
    [Tweak] bool trails = true;

    private readonly List<Burst> _bursts = new();
    private float _bend;   // -1..1 from the pitch-bend wheel
    private float _angle;
    private string _status = "";

    private sealed class Burst
    {
        public float X, Y, Size, Hue, Life = 1;
    }

    public override void Setup()
    {
        Size(720, 520);
        var inputs = MidiInputs();
        _status = inputs.Length == 0
? "No MIDI controller found -- keys 1-8 fake pad hits"
: "MIDI: " + string.Join(", ", inputs);
    }

    public override void OnMidi(MidiMessage m)
    {
        if (m.Kind == MidiKind.NoteOn)
Fire(m.Note, m.Velocity / 127f);
        else if (m.Kind == MidiKind.PitchBend)
_bend = m.Bend / 8192f;
    }

    public override void KeyPressed()
    {
        if (Key >= '1' && Key <= '8')
Fire(36 + (Key - '1'), 0.8f);
    }

    private void Fire(int note, float strength)
    {
        float a = note * 0.7f;
        _bursts.Add(new Burst
        {
X = Width / 2f + Cos(a) * radius * 0.8f,
Y = Height / 2f + Sin(a) * radius * 0.8f,
Size = 30 + strength * 160,
Hue = (hue + note * 15) % 360,
        });
    }

    public override void Draw()
    {
        if (trails)
Background(10, 12, 20, 40);
        else
Background(10, 12, 20);

        _angle += spin * 0.02f;
        float t = Millis() / 1000f;

        PushMatrix();
        Translate(Width / 2f, Height / 2f);
        Rotate(_angle + _bend * 1.2f);
        NoFill();
        StrokeWeight(2);
        for (int ring = 0; ring < 4; ring++)
        {
float r = radius * (1 - ring * 0.2f);
StrokeHSB((hue + ring * 25) % 360, 70, 100, 200);
BeginShape();
for (int i = 0; i <= 200; i++)
{
    float a = TWO_PI * i / 200;
    float petal = Sin(a * petals + t * 1.5f + ring) * wobble;
    float rr = r * (0.6f + 0.4f * Abs(Cos(a * petals / 2f))) * (1 + petal * 0.3f);
    Vertex(Cos(a) * rr, Sin(a) * rr);
}
EndShape(true);
        }
        PopMatrix();

        NoStroke();
        for (int i = _bursts.Count - 1; i >= 0; i--)
        {
var b = _bursts[i];
FillHSB(b.Hue, 60, 100, 180 * b.Life);
Circle(b.X, b.Y, b.Size * (2 - b.Life));
b.Life -= 0.03f;
if (b.Life <= 0)
    _bursts.RemoveAt(i);
        }

        Fill(255, 160);
        TextSize(13);
        Text(_status, 14, Height - 16);
    }
}