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The Nonagon (Sequencer)

The Nonagon (TheNonagonInternal in private/src/TheNonagon.hpp) is the core sequencer logic class. It wires together the Theory of Time, LameJuis, index arp, and Multi-Phasor Gate into a single unified polyphonic sequence generator.

1. Overview

The Nonagon is responsible for:

It manages 9 voices arranged in 3 trios.

2. Process Flow

For every micro block, the Theory of Time computes all samples in that block plus the first sample of the next block. Slot 8 holds the first sample of the next micro block (computed in the current block). At the start of each micro block, RolloverMicroblockBuffer copies slot 8 into slot 0—the first sample of this block was computed in the previous block. The Nonagon then runs at that sample (sequencer logic, outputs), and Process(j) for j=1..8 computes the rest of this block and the first sample of the next. This ensures that interpolation anywhere inside a micro block always has accurate boundary samples.

During a control frame, Process executes the following steps:

  1. Rollover and Theory of Time (sample 0):
    • SetTheoryOfTimeInput(input) prepares the global clock inputs.
    • m_theoryOfTime.RolloverMicroblockBuffer() copies slot 8 into slot 0 (sample 0 of this block was computed in the previous block).
    • If the global loop crosses an unmodulated cycle boundary (CrossedCycleBoundary), it records a start index in the note writer.
  2. Index Arp and LameJuis (Only on change):
    • If the Theory of Time reported position motion, startup, stop, or an accepted topology edit in the micro block (m_theoryOfTime.AnyChangeInMicroBlock()), the sequencer state must be updated.
    • SetIndexArpInputs(input) samples signed m_clockPosition from GetLoopCyclePosition(clockLoop, 0, resetLoop) when AnyTick(clockLoop) is true. Read flags follow ticks of lens dimensions, even when neighboring loop rhythm values are equal. One unit of clock position spans a complete loop cycle.
    • m_indexArp.Process(input.m_arpInput) runs the arpeggiators to find the point in the range.
    • SetLameJuisInput(input) feeds the Theory of Time gates and the index arp outputs (as m_choiceValue for the chosen strategy) into LameJuis.
    • m_lameJuis.Process(input.m_lameJuisInput) evaluates the logic matrix and sheaf to produce pitches and extra timbres.
  3. Multi-Phasor Gate (Only when running):
    • If the transport is running (m_theoryOfTime.m_samples[0].m_running), SetMultiPhasorGateInputs(input) evaluates trigger logic (pitch-changed, sub-trigger, mutes, interrupts).
    • m_multiPhasorGate.Process(input.m_multiPhasorGateInput) determines which voices emit a trigger and tracks their gate lengths based on the absolute modulated global phase.
  4. Outputs and Note Writer:
    • SetOutputs(input) gathers the results.
    • For each voice, if a trigger was emitted (m_ahdControl[i].m_trig), it:
      • Sets m_output.m_gate[i] = true.
      • Applies the trio octave switch to the LameJuis pitch (Octavize).
      • Records a note-on event (m_noteWriter.RecordNote).
    • For each triggering voice, it latches the extra timbre modulators from the LameJuis section into m_output.m_extraTimbre[i][j] (via result.m_section.Timbre(j)). These are captured per voice at trigger time and are not slewed.
    • If a voice’s gate turns off (!m_multiPhasorGate.m_gate[i]), it clears m_output.m_gate[i] and records a note-off (m_noteWriter.RecordNoteEnd).
  5. Theory of Time (samples 1–8):
    • m_theoryOfTime.Process(j, input.m_theoryOfTimeInput) is called for j = 1 through 8 to compute the rest of this micro block (samples 1–7) and the first sample of the next block (slot 8).
    • When the user transport is stopped and no voice gate keeps the timebase alive, those calls take the stopped branch of TheoryOfTimeBase::Process, keeping accepted topology and periods current and clearing phases, positions, gates, and crossing flags. Multi-Phasor Gate and LameJuis are reset before outputs are set.

3. Voice timing and loop rhythms

For each voice, SetMultiPhasorGateInputs takes the LCM of its selected clock loop’s cycle ratio and every read (non-co-muted) lens loop’s ratio. It starts at one when no clock is selected. Neither the clock contribution nor the read contribution is doubled. For clock ratio 3 and read ratio 4, m_voiceCycleRatio is 12.

The captured envelope period is globalPeriodSamples / voiceCycleRatio. Multi-Phasor Gate still ends a note gate at half of that voice cycle; this note duration is separate from the full-cycle Theory of Time rhythm step. The change does not alter clock frequency or the gate’s 0.5 cutoff. AHD’s source/global ratio, supplied from loop 0, is also separate from the voice ratio.

Each of the six input bits now has an editable loop rhythm, defaulting to a full cycle on and a full cycle off. Rhythm edits hold until that loop’s next modulated tick and do not create synthetic sequencer changes. The left rhythm and right ancestor-reset pages are available in Wrld.Bldr’s TheoryOfTimeRhythm mode; see Controller Integrations.

4. Trio Octave Switches

The Nonagon applies an octave shift per trio via TrioOctaveSwitches. The raw pitch from LameJuis is passed through Octavize(preOctave, i), which adds or subtracts octaves based on the UI state before being sent to the DSP.

5. Note Writer

The NonagonNoteWriter acts as a bridge between the core sequencer logic and the outside world (like MIDI out or UI piano rolls). It records EventData containing the voice index, pitch, wrapped unmodulated global phase position, and extra timbres. Unmodulated global cycle crossings split held notes at the display-loop boundary.

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