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#ifdef BUILD_UI
#include "SequenceSynth.h"
#include <algorithm>
#include <cmath>
namespace UI {
namespace {
float EvalEnv(const SynthNote& note, double t) {
const auto& pts = note.envPoints;
if (pts.empty()) {
return t < 0.002 ? (float)(t / 0.002) : 1.0f;
}
const float endT = pts.back().first;
if (t >= endT) {
if (note.envLoopStartT >= 0.0f && endT > note.envLoopStartT + 0.0001f) {
t = note.envLoopStartT + std::fmod(t - note.envLoopStartT, endT - note.envLoopStartT);
} else {
return pts.back().second;
}
}
float prevT = 0.0f, prevL = 0.0f;
for (const auto& [pt, lvl] : pts) {
if (t < pt) {
const float span = pt - prevT;
return span > 0.0001f ? prevL + (lvl - prevL) * (float)((t - prevT) / span) : lvl;
}
prevT = pt;
prevL = lvl;
}
return pts.back().second;
}
// Step-wise automation lookup with a monotonic cursor.
struct AutoCursor {
const std::vector<std::pair<float, float>>* track = nullptr;
size_t idx = 0;
float value = 1.0f;
void Init(const std::vector<std::pair<float, float>>& t, float startT) {
track = &t;
idx = 0;
value = t.empty() ? 1.0f : t.front().second;
Advance(startT);
}
void Advance(float t) {
while (track != nullptr && idx < track->size() && (*track)[idx].first <= t) {
value = (*track)[idx].second;
idx++;
}
}
};
} // namespace
std::vector<int16_t> Synthesize(const std::vector<SynthNote>& notes, const GainAutomation (&gainAuto)[16],
const PitchAutomation (&pitchAuto)[16], double lengthSec) {
const size_t frames = (size_t)(std::min(lengthSec + 1.5, kSynthMaxSeconds) * kSynthRate);
std::vector<float> mix(frames * 2, 0.0f);
std::vector<float> wet(frames * 2, 0.0f);
for (const auto& note : notes) {
if (note.sample == nullptr || note.sample->pcm.empty()) {
continue;
}
const std::vector<int16_t>& pcm = note.sample->pcm;
const bool looped =
note.sample->looped && note.sample->loopEnd > note.sample->loopStart && note.sample->loopEnd <= pcm.size();
const double loopStart = note.sample->loopStart;
const double loopEnd = note.sample->loopEnd;
const size_t start = (size_t)(note.startSec * kSynthRate);
const float panR = std::sqrt(std::clamp(note.pan, 0.0f, 1.0f));
const float panL = std::sqrt(1.0f - std::clamp(note.pan, 0.0f, 1.0f));
const int chan = std::clamp(note.chan, 0, 15);
AutoCursor gainCur, pitchCur;
gainCur.Init(gainAuto[chan], (float)note.startSec);
pitchCur.Init(pitchAuto[chan], (float)note.startSec);
// Release: linear at full-scale/releaseSec, optional sustain plateau.
const float relSlope = 1.0f / std::max(note.releaseSec, 0.001f);
float gateLevel = -1.0f;
float susLevel = 0.0f;
double susHoldEnd = 0.0;
// Release + sustain can extend well past the gate; bound generously.
const size_t total = (size_t)((note.soundSec + note.releaseSec + 1.0) * kSynthRate);
size_t seg = 0;
float segFreq = note.freqScale;
float segGain = 1.0f;
double pos = 0.0;
double vibPhase = 0.0;
for (size_t k = 0; k < total; ++k) {
const size_t out = start + k;
if (out >= frames) {
break;
}
if (looped && pos >= loopEnd) {
pos -= loopEnd - loopStart;
}
const size_t idx = (size_t)pos;
if (idx + 1 >= pcm.size()) {
break;
}
const double frac = pos - (double)idx;
const float smp = (float)((1.0 - frac) * pcm[idx] + frac * pcm[idx + 1]);
const double t = (double)k / kSynthRate;
while (seg < note.segs.size() && t >= note.segs[seg].t) {
segFreq = note.segs[seg].freq;
segGain *= note.segs[seg].gainMul;
seg++;
}
float env;
if (t <= note.soundSec) {
env = EvalEnv(note, t);
} else {
if (gateLevel < 0.0f) {
gateLevel = EvalEnv(note, note.soundSec);
susLevel = note.sustainLevel > 0.001f ? gateLevel * note.sustainLevel : 0.0f;
if (susLevel > 0.0f) {
// Time to fade to the sustain floor, then the engine's hold.
susHoldEnd = note.soundSec + (gateLevel - susLevel) / relSlope + note.sustainHoldSec;
}
}
const double rel = t - note.soundSec;
env = gateLevel - (float)rel * relSlope;
if (susLevel > 0.0f) {
if (t <= susHoldEnd) {
env = std::max(env, susLevel);
} else {
env = susLevel - (float)(t - susHoldEnd) * relSlope;
}
}
if (env <= 0.0f) {
break;
}
}
gainCur.Advance((float)(note.startSec + t));
pitchCur.Advance((float)(note.startSec + t));
const float v = smp * note.gain * segGain * env * gainCur.value;
mix[out * 2] += v * panL;
mix[out * 2 + 1] += v * panR;
if (note.reverb > 0.003f) {
wet[out * 2] += v * panL * note.reverb;
wet[out * 2 + 1] += v * panR * note.reverb;
}
double step = (double)segFreq * pitchCur.value;
if (note.portaSec > 0.0f && seg == 0) {
step *= std::pow((double)note.portaRatio, std::min(t / note.portaSec, 1.0));
}
if ((note.vibRateEndHz > 0.1f || note.vibRateStartHz > 0.1f) && t > note.vibDelaySec) {
const double vt = t - note.vibDelaySec;
const float rate = note.vibRateRampSec > 0.001f
? note.vibRateStartHz + (note.vibRateEndHz - note.vibRateStartHz) *
(float)std::min(vt / note.vibRateRampSec, 1.0)
: note.vibRateEndHz;
vibPhase += 6.2831853 * rate / kSynthRate;
const float depth = note.vibRampSec > 0.001f
? note.vibDepthStart + (note.vibDepthEnd - note.vibDepthStart) *
(float)std::min(vt / note.vibRampSec, 1.0)
: note.vibDepthEnd;
if (depth > 0.001f) {
step *= std::pow(2.0, depth * std::sin(vibPhase) / 12.0);
}
}
pos += step;
}
}
// Two feedback combs per side on the reverb send.
if (frames > 0) {
const int d1 = (int)(0.043 * kSynthRate);
const int d2 = (int)(0.061 * kSynthRate);
for (int side = 0; side < 2; ++side) {
for (size_t i = 0; i < frames; ++i) {
float acc = wet[i * 2 + side];
if ((int)i >= d1) {
acc += 0.42f * wet[(i - d1) * 2 + side];
}
if ((int)i >= d2) {
acc += 0.33f * wet[(i - d2) * 2 + side];
}
wet[i * 2 + side] = acc;
mix[i * 2 + side] += acc * 0.55f;
}
}
}
float peak = 1.0f;
for (const float v : mix) {
peak = std::max(peak, std::fabs(v) / 30000.0f);
}
std::vector<int16_t> out(mix.size());
for (size_t i = 0; i < mix.size(); ++i) {
out[i] = (int16_t)std::clamp(mix[i] / peak, -32000.0f, 32000.0f);
}
return out;
}
} // namespace UI
#endif // BUILD_UI
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