gaussian_filter.h

// Description: Gaussian_Filter class
// Detail: Clamped gaussian reconstruction filter
// Documentation: filters.txt

#ifndef PASTELGFX_GAUSSIAN_FILTER_H
#define PASTELGFX_GAUSSIAN_FILTER_H

#include "pastel/gfx/filter.h"

#include <cmath>

namespace Pastel
{

    class Gaussian_Filter
        : public Filter
    {
    public:
        // Using default copy constructor.
        // Using default assignment.

        explicit Gaussian_Filter(real radius = 2)
        : Filter(radius, "gaussian")
        {
        }

        virtual ~Gaussian_Filter()
        {
        }

        virtual real evaluateInRange(real x) const
        {
            // I chose the factor -2 because
            // it fitted well with the lobe of
            // the Lanczos filter. No deeper
            // science here.

            return std::exp(-2 * x * x);
        }

    private:
        Gaussian_Filter(const Gaussian_Filter& that) = delete;
        Gaussian_Filter& operator=(const Gaussian_Filter& that) = delete;
    };

    using GaussianFilterPtr = std::shared_ptr<Gaussian_Filter>;
    using ConstGaussianFilterPtr = std::shared_ptr<const Gaussian_Filter>;

    inline GaussianFilterPtr gaussianFilter(real radius = 2)
    {
        return GaussianFilterPtr(new Gaussian_Filter(radius));
    }

}

#endif