wip: State Variable Filter (FILTER LFO WORKS NOW!!!)

inc/StateVariableFilter.h

@@ -0,0 +1,35 @@
+#pragma once
+#include "Filter.h"
+#include "IEffect.h"
+#include "Settings.h"
+
+class StateVariableFilter : public IEffect {
+  protected:
+    // float* m_output; // output buffer
+    float m_fs = SAMPLE_RATE; // sampling frequency;
+    float m_fc;    // cutoff frequency normally something like: 440.0*pow(2.0,
+                   // (midi_note - 69.0)/12.0);
+    float m_res;   // resonance 0 to 1;
+    float m_drive; // internal distortion 0 to 0.1
+    float m_freq;  
+    float m_damp; 
+    float m_notcho; // notch output
+    float m_lowo;   // low pass output
+    float m_higho;  // high pass output
+    float m_bando;  // band pass output
+    float m_peako;  // peaking output = low - high
+    virtual float GetSampleForFilterType(){ return 0.0; };
+
+  public:
+    StateVariableFilter(/* args */);
+    virtual ~StateVariableFilter();
+    void Trigger() override final;
+    void Release() override final;
+    float Process(float in);
+    void Process(std::vector<float>& samples) override final;
+    void SetParameters(float freq, float res, float drive);
+    float GetFreq() { return m_fc; }
+    float GetRes() { return m_res; }
+    float GetPeakGain() { return m_drive; }
+    virtual bool IsSameFilterType(FilterType type) { return false; };
+};