mirror of
https://codeberg.org/armin/chromaflock.git
synced 2026-09-01 12:20:47 +02:00
a1cd68b6b3
Reverts the sustain-relative modulation that made F.ENV SUS and the cutoff knob feel dead while a note was held. The envelope now modulates up from the base cutoff; at env amount 0 the cutoff equals the knob, and lowering env amount darkens the held tone as expected. Also extends the filter to 24/48 dB modes (extra TPT stages), adds the matching combobox options, gives knobs a real blurred drop shadow, and updates the AGENTS.md filterType choice count.
94 lines
3 KiB
C++
94 lines
3 KiB
C++
#pragma once
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#include <cmath>
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#include <algorithm>
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enum class FilterType { LowPass12 = 0, LowPass24, BandPass, HighPass, Notch,
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BandPass24, HighPass24, Notch24, LowPass48, NumTypes };
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class Filter {
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public:
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void prepare(double sr) {
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sampleRate = sr;
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reset();
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}
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void reset() {
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for (int i = 0; i < 8; ++i)
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stage[i] = 0.0f;
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gCoeff = 0.0f;
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gTarget = 0.0f;
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kCoeff = 2.0f;
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kTarget = 2.0f;
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}
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void setCoefficients(float cutoff, float res, FilterType type) {
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cutoff = std::clamp(cutoff, 20.0f, static_cast<float>(sampleRate * 0.49));
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resonance = std::clamp(res, 0.0f, 1.0f);
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filterType = type;
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gTarget = std::tan(static_cast<float>(pi) * cutoff / static_cast<float>(sampleRate));
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kTarget = 2.0f - 2.0f * resonance;
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}
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float process(float input) {
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// Per-sample coefficient smoothing (one-pole, ~0.002 = ~44 samples to ~63%)
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gCoeff += (gTarget - gCoeff) * 0.002f;
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kCoeff += (kTarget - kCoeff) * 0.002f;
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float g = gCoeff;
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float k = kCoeff;
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float denom = 1.0f + k * g + g * g;
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float hp = (input - (k + g) * stage[0] - stage[1]) / denom;
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float bp = g * hp + stage[0];
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float lp = g * bp + stage[1];
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stage[0] = g * hp + bp;
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stage[1] = g * bp + lp;
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float hp2 = (lp - (k + g) * stage[2] - stage[3]) / denom;
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float bp2 = g * hp2 + stage[2];
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float lp2 = g * bp2 + stage[3];
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stage[2] = g * hp2 + bp2;
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stage[3] = g * bp2 + lp2;
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// Stage 3 (fed by the stage-2 lowpass) — 36 dB
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float hp3 = (lp2 - (k + g) * stage[4] - stage[5]) / denom;
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float bp3 = g * hp3 + stage[4];
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float lp3 = g * bp3 + stage[5];
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stage[4] = g * hp3 + bp3;
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stage[5] = g * bp3 + lp3;
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// Stage 4 (fed by the stage-3 lowpass) — 48 dB
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float hp4 = (lp3 - (k + g) * stage[6] - stage[7]) / denom;
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float bp4 = g * hp4 + stage[6];
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float lp4 = g * bp4 + stage[7];
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stage[6] = g * hp4 + bp4;
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stage[7] = g * bp4 + lp4;
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switch (filterType) {
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case FilterType::LowPass12: return lp;
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case FilterType::LowPass24: return lp2;
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case FilterType::BandPass: return bp;
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case FilterType::HighPass: return hp;
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case FilterType::Notch: return input - bp;
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case FilterType::BandPass24: return bp2;
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case FilterType::HighPass24: return hp2;
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case FilterType::Notch24: return input - bp2;
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case FilterType::LowPass48: return lp4;
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case FilterType::NumTypes: return input;
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}
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return lp;
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}
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private:
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static constexpr float pi = 3.14159265358979323846f;
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double sampleRate = 44100.0;
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float stage[8] = {0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f};
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float gCoeff = 0.0f, gTarget = 0.0f;
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float kCoeff = 2.0f, kTarget = 2.0f;
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float resonance = 0.0f;
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FilterType filterType = FilterType::LowPass12;
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};
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