LowPassFilter2pVector3f.hpp

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#pragma once

#include <matrix/math.hpp>

namespace math
{
class LowPassFilter2pVector3f
{
public:

    LowPassFilter2pVector3f(float sample_freq, float cutoff_freq)
    {
        // set initial parameters
        set_cutoff_frequency(sample_freq, cutoff_freq);
    }

    // Change filter parameters
    void set_cutoff_frequency(float sample_freq, float cutoff_freq);

    inline matrix::Vector3f apply(const matrix::Vector3f &sample)
    {
        // do the filtering
        const matrix::Vector3f delay_element_0{sample - _delay_element_1 *_a1 - _delay_element_2 * _a2};
        const matrix::Vector3f output{delay_element_0 *_b0 + _delay_element_1 *_b1 + _delay_element_2 * _b2};

        _delay_element_2 = _delay_element_1;
        _delay_element_1 = delay_element_0;

        return output;
    }

    // Return the cutoff frequency
    float get_cutoff_freq() const { return _cutoff_freq; }

    // Reset the filter state to this value
    matrix::Vector3f reset(const matrix::Vector3f &sample);

private:

    float _cutoff_freq{0.0f};

    float _a1{0.0f};
    float _a2{0.0f};

    float _b0{0.0f};
    float _b1{0.0f};
    float _b2{0.0f};

    matrix::Vector3f _delay_element_1{0.0f, 0.0f, 0.0f};    // buffered sample -1
    matrix::Vector3f _delay_element_2{0.0f, 0.0f, 0.0f};    // buffered sample -2
};

} // namespace math