feat: all filter types

inc/BandPassFilter.h

@@ -1,14 +1,17 @@
 #pragma once
+
 #include "Filter.h"
 
 class BandPassFilter : public Filter {
-  private:
-    void CalculateCoefficients() override;
+  protected:
+    float GetSampleForFilterType() override;
 
   public:
+    BandPassFilter();
     BandPassFilter(Filter* filter);
     BandPassFilter(float freq, float res, float q);
-    BandPassFilter(/* args */);
     ~BandPassFilter();
     bool IsSameFilterType(FilterType type) override { return type == BandPass; };
 };
+
+