rmx-19/Source/SynthEngine.cpp

#include "SynthEngine.h"

SynthEngine::SynthEngine()  { rng.setSeedRandomly(); }
SynthEngine::~SynthEngine() {}

void SynthEngine::setSampleRate (double s)
{
    sr = s;
}

float SynthEngine::osc (int wave, double ph, double phRaw)
{
    switch (wave)
    {
        case 0:  return (float) std::sin (ph * 2.0 * juce::MathConstants<double>::pi);
        case 1:  return (float) (ph < 0.5 ? 4.0 * ph - 1.0 : 3.0 - 4.0 * ph);
        case 2:  return (float) (1.0 - 2.0 * ph);
        case 3:  return (float) (ph < 0.5 ? -1.0 : 1.0);
        case 4:  return rng.nextFloat() * 2.0f - 1.0f;

        // 5 FM: 2-op sine FM (1:2 ratio), index slowly evolves over the note
        case 5:
        {
            const double idx = 2.2 + 1.6 * (0.5 + 0.5 * std::sin (phRaw * 0.03));
            return (float) std::sin (ph * 2.0 * juce::MathConstants<double>::pi
                                     + idx * std::sin (ph * 4.0 * juce::MathConstants<double>::pi));
        }
        // 6 PWM: pulse whose width animates with the running phase
        case 6:
        {
            const double w = 0.05 + 0.60 * (0.5 + 0.5 * std::sin (phRaw * 0.05));
            return (float) (ph < w ? 1.0 : -1.0);
        }
        // 7 SUPRSW: 5 stacked saws with a slowly moving spread (detuned-stack feel)
        case 7:
        {
            const double df = 0.006 * std::sin (phRaw * 0.02);
            double s = 0.0;
            for (int k = -2; k <= 2; ++k)
            {
                double sp = ph + df + k * 0.13;
                sp -= std::floor (sp);
                s += 1.0 - 2.0 * sp;
            }
            return (float) (s * 0.28);
        }
        // 8 DBLSAW: saw plus a sub-octave saw (big, weighted low end)
        case 8:
        {
            double sub = ph * 0.5;
            sub -= std::floor (sub);
            return (float) (0.56 * (1.0 - 2.0 * ph) + 0.44 * (1.0 - 2.0 * sub));
        }
        // 9 WARP: saw pushed twice through a wavefolder -> bright, buzzy, raw
        case 9:
        {
            double x = 1.0 - 2.0 * ph;
            x = 1.0 - 2.0 * std::fabs (1.0 - std::fabs (x));
            x = 1.0 - 2.0 * std::fabs (1.0 - std::fabs (x));
            return (float) x;
        }
        // 10 HSYNC: saw hard-synced to a 2.5x master -> bright, cutting lead
        case 10:
        {
            double sp = ph * 2.5;
            sp -= std::floor (sp);
            return (float) (1.0 - 2.0 * sp);
        }
        // 11 TINE: electric-tine partial stack (1x,2x,4x,8x) -> bell/marimba/EP
        case 11:
        {
            const double a = ph * 2.0 * juce::MathConstants<double>::pi;
            return (float) (0.44 * std::sin (a)
                          + 0.28 * std::sin (2.0 * a)
                          + 0.18 * std::sin (4.0 * a)
                          + 0.09 * std::sin (8.0 * a));
        }
        // 12 SEQ: 8 pseudo-random levels per cycle -> digital, step-sequencer
        case 12:
        {
            static const float L[8] = { 0.90f, -0.45f, 0.30f, -0.85f,
                                        0.55f, -0.20f, 0.75f, -0.60f };
            const int k = (int) std::floor (ph * 8.0);
            return L[k & 7];
        }
        // 13 CHORD: built-in minor triad (root, m3, 5th) -> one-osc chord
        case 13:
        {
            const double a = ph * 2.0 * juce::MathConstants<double>::pi;
            return (float) (0.44 * std::sin (a)
                          + 0.30 * std::sin (a * (6.0 / 5.0))
                          + 0.27 * std::sin (a * 1.5));
        }
        // 14 SUPRPL: 3 stacked phase-offset pulse waves -> fat chorus-box square
        case 14:
        {
            const double o1 = ph < 0.5 ? 1.0 : -1.0;
            double p2 = ph + 0.10; p2 -= std::floor (p2);
            const double o2 = p2 < 0.5 ? 1.0 : -1.0;
            double p3 = ph + 0.25; p3 -= std::floor (p3);
            const double o3 = p3 < 0.5 ? 1.0 : -1.0;
            return (float) ((o1 + o2 + o3) * (1.0 / 3.0));
        }
        default: return 0.0f;
    }
}

void SynthEngine::allNotesOff (bool immediate)
{
    for (auto& v : voices)
    {
        if (v.active)
        {
            if (immediate) v.active = false;
            else           v.amp.noteOff();
        }
    }
    sustainedNotes.clear();
    if (immediate) active = 0;
}

void SynthEngine::sustainPedal (bool down)
{
    pedal = down;
    if (! down)
    {
        for (auto n : sustainedNotes)
            for (auto& v : voices)
                if (v.active && v.note == n)
                    v.amp.noteOff();
        sustainedNotes.clear();
    }
}

void SynthEngine::pitchBend (float cents) { bendCents = cents; }
void SynthEngine::modWheel (float v)      { mod = juce::jlimit (0.0f, 1.0f, v); }

SynthEngine::Voice* SynthEngine::acquireVoice()
{
    const int lim = juce::jlimit (1, maxVoice, polyLimit);
    for (int i = 0; i < lim; ++i)
        if (! voices[i].active)
            return &voices[i];

    stealIdx = (stealIdx + 1) % lim;
    Voice* v = &voices[stealIdx];
    if (v->active)
    {
        v->amp.noteOff();
        v->flt.noteOff();
    }
    return v;
}

void SynthEngine::noteOn (int midiNote, float velocity)
{
    const float noteFreq = (float) (440.0 * std::exp2 ((midiNote - 69.0) / 12.0));
    Voice* v = acquireVoice();
    const bool fresh = ! v->active;
    v->active = true;
    v->note = midiNote;
    v->vel = 1.0f - std::pow (1.0f - velocity, 1.35f);
    v->curFreq  = (lastGlide > 0.001f && lastNoteFreq > 0.0f) ? lastNoteFreq : noteFreq;
    v->targetFreq = noteFreq;
    v->ph1 = rng.nextDouble() * 0.5;
    v->ph2 = rng.nextDouble() * 0.5;
    v->ph1r = rng.nextDouble() * 8.0;
    v->ph2r = rng.nextDouble() * 8.0;
    v->lfoPh = rng.nextDouble();
    v->lfoIdx = 0;
    v->lfoSH = rng.nextFloat() * 2.0f - 1.0f;
    v->lp = v->bp = 0.0f;
    v->fcSm = 0.0f;
    v->outSmooth = 0.0f;
    v->drift = 0.0f;
    v->driftT = rng.nextFloat() * 2.0f - 1.0f;
    // Micro Q-style unison: every voice gets its own small detune offset, the
    // spread widening with the DETUNE 1 setting, for fat stacks on chords
    v->dtSp = (rng.nextFloat() * 2.0f - 1.0f) * (1.5f + 0.30f * std::abs (curDetune1));

    const float p = juce::jlimit (-1.0f, 1.0f, lastPan + (rng.nextFloat() - 0.5f) * 0.1f);
    const float ang = (p + 1.0f) * juce::MathConstants<float>::pi * 0.25f;
    const float mag = 0.7071f + 0.25f * rng.nextFloat();
    v->panL = std::cos (ang) * mag;
    v->panR = std::sin (ang) * mag;

    v->amp.reset(); v->flt.reset();
    v->amp.noteOn(); v->flt.noteOn();
    lastNoteFreq = noteFreq;
    if (fresh) ++active;
}

void SynthEngine::noteOff (int midiNote)
{
    if (pedal)
    {
        if (! sustainedNotes.contains (midiNote))
            sustainedNotes.add (midiNote);
        return;
    }
    for (auto& v : voices)
        if (v.active && v.note == midiNote)
            v.amp.noteOff();
}

void SynthEngine::render (const VParams& p, float* left, float* right, int num)
{
    curDetune1 = p.detune1;
    for (auto& v : voices)
    {
        v.amp.setRates (p.ampA, p.ampD, p.ampS, p.ampR, sr);
        v.flt.setRates (p.fA,    p.fD,    p.fS,    p.fR,    sr);
    }
    lastGlide = p.glide;
    lastPan   = p.pan;
    polyLimit = juce::jlimit (1, maxVoice, (int) p.poly);

    const float glideRate = p.glide <= 0.001f ? 1.0f
                         : 1.0f - std::exp (-1.0f / (p.glide * (float) sr));
    const float detuneRatio2 = std::exp2f (p.detune / 1200.0f);
    const float detuneRatio1 = std::exp2f (p.detune1 / 1200.0f);
    const float tuneRatio   = std::exp2f (p.tune / 12.0f);
    const float ctuneRatio1 = std::exp2f (p.ctune1 / 12.0f);
    const float ctuneRatio2 = std::exp2f (p.ctune2 / 12.0f);
    const float maxFc = 0.4f * (float) sr;
    const float minFc = 30.0f;

    // Free-running slow-evolution clock: every ~8 s the running patch rolls a
    // new wander target, and evoCur slews toward it, so harmonic character,
    // tuning instability and cross-mod bloom all slowly drift and come back.
    // Generative evolution clock. evoCur is a true brownian walk that roams the
    // whole [-1,1] range without ever repeating, plus occasional "excursions"
    // that push it to a freshly rolled extreme for 7-18 s. evoSlow is a second,
    // much slower wander that drives the long-arc soundscape drift over 1-3
    // minutes. Together they make a held note slowly change character forever.
    for (int s = 0; s < num; ++s)
    {
        if (--evoGoalT <= 0.0)
        {
            evoGoalT = sr * (7.0 + rng.nextDouble() * 11.0);
            evoGoal = (rng.nextFloat() < 0.5f ? -1.0f : 1.0f)
                      * (0.65f + 0.35f * rng.nextFloat());
            for (auto& v : voices)
                if (v.active)
                    v.driftT = rng.nextFloat() * 2.0f - 1.0f;
        }
        evoCur += (rng.nextFloat() - 0.5f) * 0.0022f
                + (evoGoal - evoCur) * 0.00035f;
        evoCur = std::max (-1.0f, std::min (1.0f, evoCur));

        evoSlow += (rng.nextFloat() - 0.5f) * 0.0028f
                 + (0.0f - evoSlow) * 0.0000002f;
        evoSlow = std::max (-1.0f, std::min (1.0f, evoSlow));

        float mixL = 0.0f, mixR = 0.0f;
        int activeCount = 0;
        for (auto& v : voices)
            if (v.active) ++activeCount;
        const float voiceGain = activeCount > 1 ? 1.0f / std::sqrtf ((float) activeCount) : 1.0f;

        for (auto& v : voices)
        {
            if (! v.active)
                continue;

            if (p.glide > 0.001f)
                v.curFreq += (v.targetFreq - v.curFreq) * glideRate;
            else
                v.curFreq = v.targetFreq;

            // LFO
            v.lfoPh += (double) p.lfoRate / sr;
            while (v.lfoPh >= 1.0)
            {
                v.lfoPh -= 1.0;
                v.lfoIdx++;
                v.lfoSH = rng.nextFloat() * 2.0f - 1.0f;
            }

            float lfo = 0.0f;
            switch ((int) p.lfoShape)
            {
                case 0: lfo = (float) std::sin (v.lfoPh * 2.0 * juce::MathConstants<double>::pi); break;
                case 1: lfo = (float) (v.lfoPh < 0.5 ? 4.0 * v.lfoPh - 1.0 : 3.0 - 4.0 * v.lfoPh); break;
                case 2: lfo = v.lfoPh < 0.5 ? -1.0f : 1.0f; break;
                case 3: lfo = v.lfoSH; break;
                default: lfo = 0.0f; break;
            }

            // frequency, vibrato, bend, tune
            float freq = v.curFreq * tuneRatio;
            if ((int) p.lfoTarget == 1)
                freq *= std::exp2f (lfo * p.lfoDepth * 1.6f / 12.0f);
            if (p.evolve > 0.001f)
            {
                // slow random tuning instability, re-rolled with each excursion
                v.drift += (v.driftT - v.drift) * 0.0020f;
                freq *= std::exp2f (v.drift * p.evolve * 14.0f / 1200.0f);
            }
            if (bendSmooth != bendCents)
                bendSmooth += (bendCents - bendSmooth) * 0.08f;
            freq *= std::exp2f (bendSmooth / 1200.0f);

            const float d1 = (float) (freq / sr) * detuneRatio1 * ctuneRatio1 * std::exp2f (v.dtSp / 1200.0f);
            // soundscape detune sway: osc2 slowly zooms its detune in/out
            const float swayT = std::exp2f (evoSlow * p.evolve * 16.0f / 1200.0f);
            const float d2 = (float) (freq / sr) * detuneRatio2 * ctuneRatio2 * swayT;

            v.ph1 += d1; if (v.ph1 >= 1.0) v.ph1 -= 1.0;
            v.ph1r += d1;

            // cross-mod "bloom": the amount breathes with the evolution walk
            // (scaled by EVOLVE, so at evolve=0 it sits static at its middle value),
            // sometimes vanishing almost entirely, sometimes saturating
            float xmA = 0.0f;
            if ((int) p.xmod > 0 && p.xmix > 0.001f)
                xmA = p.xmix * (0.55f + 0.45f * evoCur * p.evolve);

            // oscillators, with osc1 phase-modulating osc2 when in FM cross-mod
            const float o1 = osc ((int) p.osc1w, v.ph1, v.ph1r);
            float d2step = d2;
            if ((int) p.xmod == 2 && xmA > 0.0f)
                d2step = d2 * (1.0f + o1 * xmA);
            v.ph2 += d2step; if (v.ph2 >= 1.0) v.ph2 -= 1.0;
            v.ph2r += d2step;
            const float o2 = osc ((int) p.osc2w, v.ph2, v.ph2r);
            // osc-mix crossfade: the o1<->o2 balance slowly sways with the
            // soundscape wander, visibly respraying the whole timbre over ~a minute
            const float mixBase = p.oscMix * 0.01f;
            float mixb = mixBase * (1.0f + evoSlow * p.evolve * 0.8f);
            mixb = std::max (0.0f, std::min (0.98f, mixb));
            float sig = o1 * (1.0f - mixb) + o2 * mixb;

            // ring / AM cross-mod spiced into the mix
            if (xmA > 0.0f)
            {
                const int xm = (int) p.xmod;
                if (xm == 1)      sig += o1 * o2 * 0.35f * xmA;
                else if (xm == 3) sig += o1 * o2 * 0.55f * xmA;
            }

            // spectral warp: drive + bias swing hard with the texture wander,
            // folding harmonics way in and pulling back out over tens of seconds
            if (p.warp > 0.001f)
            {
                const float drive = 1.0f + p.warp * (1.0f + 3.2f * std::max (0.0f, evoCur));
                sig = std::tanh (sig * drive + evoCur * 0.30f * p.warp);
            }

            const float fe = v.flt.next();

            // gentle analog drive ahead of the filter (resonance pushes harder)
            sig = std::tanh (sig * (1.0f + p.fltRes * 0.15f));

            // cutoff with keytrack + filter envelope + LFO + mod wheel
            float fc = p.fltCut;
            fc *= std::exp2f (p.fltKey * 0.01f * std::log2f (freq / 261.6256f));
            fc *= std::exp2f (p.fltEnv * 0.01f * fe * std::log2f (maxFc / fc));
            if ((int) p.lfoTarget == 0)
                fc *= std::exp2f (lfo * p.lfoDepth * 10.0f / 12.0f);
            if (p.evolve > 0.001f)
                fc *= std::exp2f (evoCur * p.evolve * 4.0f / 12.0f);
            fc *= std::exp2f (mod);
            fc = std::min (maxFc, std::max (minFc, fc));
            v.fcSm += (fc - v.fcSm) * 0.25f;
            fc = v.fcSm;

            // SVF (cap f1 to keep the Chamberlin structure stable; past ~1.5 the
            // resonance feedback can self-oscillate and sputter at maxed cutoff+res)
            const float f1 = std::min (1.50f, 2.0f * std::sin (juce::MathConstants<float>::pi * fc / (float) sr));
            // resonance growl: filter tightens/loosens with the soundscape wander
            const float q1 = 1.0f / (1.0f + p.fltRes * (3.0f + evoCur * p.evolve * 2.5f));
            v.f1c = f1;
            const float hp = sig - v.lp - q1 * v.bp;
            v.bp += f1 * hp;
            v.lp += f1 * v.bp;

            // The Chamberlin band-pass and high-pass taps carry less energy
            // than the low-pass tap for harmonically rich osc waves, so
            // compensate to keep filter types at a comparable loudness level.
            float filtered = sig;
            switch ((int) p.fltType)
            {
                case 1: filtered = v.lp; break;
                case 2: filtered = v.bp * 1.5f; break;
                case 3: filtered = hp * 1.4f;   break;
                default: break;
            }

            // amplitude envelope (+ tremolo if LFO targets amp)
            const float ae = v.amp.next();
            float ampMod = 1.0f;
            if ((int) p.lfoTarget == 2)
                ampMod = 1.0f - p.lfoDepth * 0.5f * (1.0f + lfo);
            ampMod *= 1.0f + evoSlow * p.evolve * 0.10f;

            v.outSmooth += (filtered - v.outSmooth) * 0.12f;
            float o = v.outSmooth * (ae * ampMod) * v.vel * voiceGain;
            if (! std::isfinite (o)) o = 0.0f;

            mixL += o * v.panL;
            mixR += o * v.panR;

            if (v.amp.getState() == Env::Off)
            {
                v.active = false;
                if (active > 0) --active;
            }
        }

        if (! std::isfinite (mixL)) mixL = 0.0f;
        if (! std::isfinite (mixR)) mixR = 0.0f;

        // Soft limiter before tanh for cleaner saturation
        mixL = std::tanh (mixL * 0.8f);
        mixR = std::tanh (mixR * 0.8f);

        left[s]  += mixL;
        right[s] += mixR;
    }
}