Implement low pass filter in separate module

flix/lpf.h

@@ -0,0 +1,42 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Low pass filter implementation
+
+#pragma once
+
+template <typename T> // Using template to make the filter usable for scalar and vector values
+class LowPassFilter
+{
+public:
+	float alpha; // smoothing constant, 1 means filter disabled
+	T output;
+
+	LowPassFilter(float alpha): alpha(alpha) {};
+
+	T update(const T input)
+	{
+		if (alpha == 1) { // filter disabled
+			return input;
+		}
+
+		if (!initialized) {
+			output = input;
+			initialized = true;
+		}
+		return output = output * (1 - alpha) + input * alpha;
+	}
+
+	void setCutOffFrequency(float cutOffFreq, float dt)
+	{
+		alpha = 1 - exp(-2 * PI * cutOffFreq * dt);
+	}
+
+	void reset()
+	{
+		initialized = false;
+	}
+
+private:
+	bool initialized = false;
+};