serumalt/Source/LFO.cpp

#include "LFO.h"

namespace serum
{

void LFO::reset()
{
    phase = 0.0;
    value = 0.0f;
    delayCounter = 0.0;
    fadeCounter  = 0.0;
    fadeVal      = 1.0f;
    holdValue    = rng.nextFloat() * 2.0f - 1.0f;
    prevDelayParam = -1.0f;
    prevFadeParam  = -1.0f;
    if (shapeBuffer.empty())
    {
        shapeBuffer.resize ((size_t) kShapePoints);
        // default step sequence
        for (int i = 0; i < kShapePoints; ++i)
            shapeBuffer[(size_t) i] = (i % 2 == 0) ? 1.0f : -1.0f;
    }
}

void LFO::setParams (float rateNorm, bool s, float b, int shp, float ph,
                     float fade, float delay)
{
    sync  = s;
    beat  = b;
    shape = juce::jlimit (0, (int) LfoShape::Count - 1, shp);
    phaseOffset = juce::jlimit (0.0f, 1.0f, ph);

    if (sync)
        rateHz = (tempo / 60.0) / maps::beatToMultiplier (beat);
    else
        rateHz = maps::rateToHz (rateNorm);

    delaySeconds = juce::jlimit (0.0f, 1.0f, delay) * 4.0;
    fadeSeconds  = juce::jlimit (0.0f, 1.0f, fade) * 8.0;

    // Only restart the delay/fade timing when those knobs actually change,
    // so repeated block-rate setParams calls don't keep resetting the LFO.
    if (delay != prevDelayParam || fade != prevFadeParam)
    {
        delayCounter = delaySeconds * sr;
        fadeCounter  = 0.0;
        fadeVal      = (fadeSeconds <= 0.0) ? 1.0f : 0.0f;
        prevDelayParam = delay;
        prevFadeParam  = fade;
    }
    value = delayCounter > 0.0 ? 0.0f : shapeValue() * fadeVal;
}

void LFO::setShapeData (const std::vector<float>& data, int steps)
{
    if (data.empty())
        return;

    shapeSteps = juce::jlimit (2, kShapePoints, steps);
    for (size_t i = 0; i < shapeBuffer.size(); ++i)
        shapeBuffer[i] = i < data.size() && std::isfinite (data[i])
                            ? juce::jlimit (-1.0f, 1.0f, data[i]) : 0.0f;
}

float LFO::shapeValue() noexcept
{
    const float p = getPhase();
    switch ((LfoShape) shape)
    {
        case LfoShape::Sine:
            return std::sin (p * juce::MathConstants<float>::twoPi);
        case LfoShape::Triangle:
            return 1.0f - 4.0f * std::abs (p - 0.5f);
        case LfoShape::Saw:
            return 2.0f * p - 1.0f;
        case LfoShape::Square:
            return (p < 0.5f) ? 1.0f : -1.0f;
        case LfoShape::SampleHold:
            return holdValue;
        case LfoShape::StepSeq:
        {
            const int idx = juce::jlimit (0, shapeSteps - 1, (int) (p * shapeSteps));
            return shapeBuffer[(size_t) idx];
        }
        case LfoShape::Freehand:
        {
            const float pos = p * (float) (shapeSteps - 1);
            const int i0 = (int) pos;
            const int i1 = juce::jmin (i0 + 1, shapeSteps - 1);
            const float frac = pos - (float) i0;
            return shapeBuffer[(size_t) i0] * (1.0f - frac) + shapeBuffer[(size_t) i1] * frac;
        }
        default:
            return 0.0f;
    }
}

float LFO::process() noexcept
{
    return advance (1);
}

float LFO::advance (int numSamples) noexcept
{
    if (numSamples <= 0)
        return value;

    // Start delay.
    if (delayCounter > 0.0)
    {
        const int skipped = (int) juce::jmin ((double) numSamples, std::ceil (delayCounter));
        delayCounter = juce::jmax (0.0, delayCounter - skipped);
        numSamples -= skipped;
        if (numSamples == 0)
            return value = 0.0f;
    }

    // Fade-in ramp.
    if (fadeVal < 1.0f)
    {
        fadeCounter += numSamples;
        if (fadeSeconds > 0.0)
            fadeVal = (float) juce::jlimit (0.0, 1.0, fadeCounter / (fadeSeconds * sr));
        else
            fadeVal = 1.0f;
    }

    phase += rateHz * numSamples / sr;
    const double cycles = std::floor (phase);
    phase -= cycles;
    if (shape == (int) LfoShape::SampleHold)
        for (int i = 0; i < (int) cycles; ++i)
            holdValue = rng.nextFloat() * 2.0f - 1.0f;

    value = shapeValue() * fadeVal;
    return value;
}

} // namespace serum