create-parameter

name	create-parameter
description	How to add a new parameter to Smart Grid One. Covers ForEachSmartGridOneParam, SetEncoderParameters wiring, PhaseUtils (ExpParam, ZeroedExpParam), and ParamSlew for oversampled blocks. Use when adding a new knob/parameter, creating a control, or wiring encoders to DSP.

Creating a Parameter in Smart Grid One

Overview

Adding a parameter requires: (1) declaring it in the parameter list, (2) wiring it in SetEncoderParameters, and optionally (3) using exponential mapping or per-sample slew for oversampled blocks.

Step 1: Add to ForEachSmartGridOneParam.hpp

Add an F(...) line in private/src/ForEachSmartGridOneParam.hpp:

F(name, shortName, bank, x, y, default, "Description", color, sourceMachines, filterMachines)

• name: C++ enum identifier (e.g. MyParam)
• shortName: 3–4 char label for encoder display (e.g. MYP)
• bank: Source, FilterAndAmp, PanningAndSequencing, VoiceLFOs, etc.
• x, y: Grid position 0–3 within the bank
• default: Normalized default in [0, 1]
• sourceMachines / filterMachines: MachineFlags::x_all for all machines, or MachineFlags::x_dualWaveShapingVCOOnly etc. for machine-specific params

Example:

F(MyCutoff, CUT, FilterAndAmp, 2, 2, 0.5, "My Cutoff", SmartGrid::Color::Green, MachineFlags::x_all, MachineFlags::x_all)

Step 2: Wire in SetEncoderParameters (SquiggleBoy.hpp)

In SetEncoderParameters(Input& input), add the assignment in the appropriate loop:

• Voice params: Inside the for (size_t i = 0; i < x_numVoices; ++i) loop. Use m_encoders.GetValue(Param::MyParam, i) or GetValueNoSlew(Param::MyParam, i).
• Quad params (e.g. delay): Inside the for (int i = 0; i < 4; ++i) loop for delay/reverb.
• Global params: Outside loops, no voice index: m_encoders.GetValue(Param::MyParam).

Assign to the correct input struct member (m_state[i].m_vcoInput, m_filterInput, m_ampInput, etc.).

GetValue vs GetValueNoSlew

• GetValue: Encoder applies its own slew. Use when the value goes directly to DSP without further processing (e.g. pan radius, LFO shape, AHD params).
• GetValueNoSlew: Raw value. Use when:
  • Feeding into ExpParam.Update() or ZeroedExpParam.Update() (they handle their own response)
  • The destination has its own slew (e.g. ParamSlew in oversampled blocks)
  • The parameter is consumed at control rate and you want no encoder slew

Step 3: Exponential Parameters (PhaseUtils)

For parameters that should feel exponential (e.g. cutoff, gain, pitch):

ExpParam

Maps [0, 1] to [min, max] exponentially.

• Add member to input struct: PhaseUtils::ExpParam m_myParam;
• Constructor: ExpParam(base) for single-base, or ExpParam(min, max) for explicit range
• In SetEncoderParameters: m_state[i].m_xxxInput.m_myParam.Update(m_encoders.GetValueNoSlew(Param::MyParam, i));
• Use m_myParam.m_expParam in DSP

Example (PitchOffset): ExpParam(4) → value 0 → 1×, value 1 → 4×.

ZeroedExpParam

Maps [0, 1] to [0, max] with 0 at knob 0. Use for modulation depth, crossfade, etc.

• Add member: PhaseUtils::ZeroedExpParam m_myParam;
• Constructor: ZeroedExpParam(base) (default base 20)
• Same Update pattern as ExpParam
• Optional: SetMax(max) or SetBaseByCenter(center) for curve shaping

Step 4: Parameters in Oversampled Blocks

If the parameter is consumed inside an oversampled block (e.g. DualWaveShapingVCO::ProcessUBlock), it must be slewed at the oversample rate to avoid zipper noise.

Option A: Raw float → ParamSlew

For simple linear params (e.g. m_v, m_d, m_fade):

1. Input struct: float m_myParam;
2. Consuming block: add ParamSlew m_myParamSlew; with ParamSlew(x_oversample) in constructor
3. In ProcessUBlock: m_myParamSlew.Update(input.m_myParam); at start of block
4. In inner loop: float val = m_myParamSlew.Process(); each sample

Option B: ExpParam → ParamSlew over m_expParam

For exponential params used per-sample:

1. Input struct: PhaseUtils::ExpParam m_myParam; (or ZeroedExpParam)
2. SetEncoderParameters: m_xxxInput.m_myParam.Update(m_encoders.GetValueNoSlew(Param::MyParam, i));
3. Consuming block: add ParamSlew m_myParamSlew; with ParamSlew(x_oversample)
4. In ProcessUBlock: m_myParamSlew.Update(input.m_myParam.m_expParam); at start
5. In inner loop: float val = m_myParamSlew.Process();

See DualWaveShapingVCO.hpp for m_offsetFreqFactorSlew, m_detuneSlew, m_crossModIndexSlew.

Additional context

For encoder architecture, tracks/voices, modulation, and machine-specific parameters, see encoder-system.md.

For the full system map (DSP, Theory of Time, LameJuis, etc.), see docs index.

Checklist

• F(...) added in ForEachSmartGridOneParam.hpp with bank, grid slot, machine flags
• Assignment added in SetEncoderParameters in correct loop (voice/quad/global)
• GetValue vs GetValueNoSlew chosen correctly
• If exponential: ExpParam or ZeroedExpParam in input struct, .Update() in SetEncoderParameters
• If oversampled: ParamSlew in consuming block, Update at block start, Process() per sample