[feat]: Filter (#18)

closes #16

Reviewed-on: #18

inc/LowPassFilter.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include "Filter.h"
+
+class LowPassFilter : public Filter {
+  protected:
+    void CalculateCoefficients() override;
+
+  public:
+    LowPassFilter();
+    LowPassFilter(Filter* filter);
+    LowPassFilter(float freq, float res, float q);
+    ~LowPassFilter();
+    bool IsSameFilterType(FilterType type) override { return type == LowPass; };
+};