From 4057bf5d42b3ab5afb04efa38e2dbe67a64f00d6 Mon Sep 17 00:00:00 2001
From: HiveBeats <e1lama@protonmail.com>
Date: Fri, 8 Sep 2023 15:40:31 +0400
Subject: [PATCH] wip: filter lfo

---
 inc/Adder.h           |  2 +-
 inc/Oscillator.h      |  2 +-
 inc/Synth.h           |  3 ++-
 src/Filter.cpp        |  3 ++-
 src/LowPassFilter.cpp |  2 +-
 src/Oscillator.cpp    |  2 +-
 src/Synth.cpp         | 12 ++++++++++++
 7 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/inc/Adder.h b/inc/Adder.h
index 3052b15..186bf9d 100644
--- a/inc/Adder.h
+++ b/inc/Adder.h
@@ -13,7 +13,7 @@ struct Adder {
         for (size_t i = 0; i < sample_count; i++) {
             float sample = 0.0f;
             for (Oscillator* osc : oscillators) {
-                sample += osc->GenerateSample(1.f);
+                sample += osc->GenerateSample();
             }
 
             signal[i] = sample;
diff --git a/inc/Oscillator.h b/inc/Oscillator.h
index 1e33fa8..6944653 100644
--- a/inc/Oscillator.h
+++ b/inc/Oscillator.h
@@ -31,5 +31,5 @@ class Oscillator {
     float GetFreq() { return m_freq; }
     void SetFreq(float freq);
     void Reset();
-    float GenerateSample(float duration);
+    float GenerateSample();
 };
diff --git a/inc/Synth.h b/inc/Synth.h
index 4c1ffbd..b1609ce 100644
--- a/inc/Synth.h
+++ b/inc/Synth.h
@@ -15,13 +15,14 @@ class Synth {
     std::vector<Oscillator*> m_oscillators;
     std::vector<Effect*> m_effects;
     std::vector<float> m_out_signal;
+    Oscillator* m_lfo;
     void zero_signal();
     void get_note();
     void trigger_note_on_effects();
     void untrigger_note_on_effects();
     void apply_effects();
     void add_oscillator();
-
+    void apply_filter_lfo();
   public:
     Synth(/* args */);
     ~Synth();
diff --git a/src/Filter.cpp b/src/Filter.cpp
index 386f8f2..181f72e 100644
--- a/src/Filter.cpp
+++ b/src/Filter.cpp
@@ -18,6 +18,7 @@ void Filter::Trigger() {}
 void Filter::Release() {}
 
 float Filter::Process(float in) {
+    calculate_coefficients();
     float out = in * m_a0 + m_z1;
     m_z1 = in * m_a1 + m_z2 - m_b1 * out;
     m_z2 = in * m_a2 - m_b2 * out;
@@ -28,7 +29,7 @@ void Filter::Process(std::vector<float>& samples) {
     // todo: that will not work for ADSR-controlled filter. So, let's calculate
     // all the possible frequency values into array/dictionary then just lookup
     // for each sample
-    calculate_coefficients();
+    
     for (std::size_t i = 0; i < samples.size(); i++) {
         samples[i] = Process(samples[i]);
     }
diff --git a/src/LowPassFilter.cpp b/src/LowPassFilter.cpp
index ca4a776..9d43e56 100644
--- a/src/LowPassFilter.cpp
+++ b/src/LowPassFilter.cpp
@@ -4,7 +4,7 @@
 LowPassFilter::LowPassFilter() {
     // todo: defaults
     m_freq = 200.f / SAMPLE_RATE;
-    m_q = 0.707f;
+    m_q = 1.0f;//0.707f;
     m_order = 0;
 }
 
diff --git a/src/Oscillator.cpp b/src/Oscillator.cpp
index cf6e940..ce1f78a 100644
--- a/src/Oscillator.cpp
+++ b/src/Oscillator.cpp
@@ -45,7 +45,7 @@ void Oscillator::SetFreq(float freq) {
     m_phase_dt = (this->*m_dt_function)(freq);
 }
 
-float Oscillator::GenerateSample(float duration) {
+float Oscillator::GenerateSample() {
     return (this->*m_osc_function)() * m_volume;
 }
 
diff --git a/src/Synth.cpp b/src/Synth.cpp
index 1ea0484..d4b2591 100644
--- a/src/Synth.cpp
+++ b/src/Synth.cpp
@@ -6,6 +6,7 @@
 #include "LowPassFilter.h"
 
 Synth::Synth(/* args */) {
+    m_lfo = new Oscillator(OscillatorType::Sine, 5.f, VOLUME);
     add_oscillator();
     add_oscillator();
     AddEffect(new ADSR());
@@ -69,7 +70,18 @@ void Synth::Trigger(Note input) {
     trigger_note_on_effects();
 }
 
+void Synth::apply_filter_lfo() {
+    float dt = m_lfo->GenerateSample();
+    Filter* filter = (Filter*)m_effects[1];
+    float freq = filter->GetFreq();
+    //todo: check formula
+    //filter->SetParameters(freq + dt * 0.2f, filter->GetRes(), filter->GetPeakGain());
+}
+
 void Synth::Process() {
+    //todo: on each sample. 
+    //in order to do that, we need to move to per-sample processing
+    apply_filter_lfo();
     get_note();
     apply_effects();
 }