wip: filter lfo

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]);
     }

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;
 }
 

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;
 }
 

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();
 }