_curve_func.h

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/* === S T A R T =========================================================== */

#ifndef __ETL__CURVE_FUNC_H
#define __ETL__CURVE_FUNC_H

/* === H E A D E R S ======================================================= */

#include <functional>
#include "_fixed.h"

/* -- C L A S S E S --------------------------------------------------------- */

template <class T, class K=float>
struct affine_combo
{
    // from (a) to (x) : x = a(1-t) + b(t)
    T operator()(const T &a,const T &b,const K &t)const
    {
        return T( (b-a)*t+a );
    }

    // from (x) to (a) : a = (x-b(t)) / (1-t)
    T reverse(const T &x, const T &b, const K &t)const
    {
        return T( (x-t*b)*(static_cast<K>(1)/(static_cast<K>(1)-t)) );
    }
};

template <class T, class K=float>
struct distance_func : public std::binary_function<T, T, K>
{
    K operator()(const T &a,const T &b)const
    {
        T delta=b-a;
        return static_cast<K>(delta*delta);
    }

    K cook(const K &x)const { return x*x; }
    K uncook(const K &x)const { return sqrt(x); }

};

/* -- E N D ----------------------------------------------------------------- */

#endif