NRE_Math.hpp

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    #pragma once

    #include <cmath>
    #include <type_traits>

    namespace NRE {
        namespace Math {
    
            template <class ...>
            struct ArithmeticChecker : std::true_type {
            };
            template <class T1, class ... Tn>
            struct ArithmeticChecker<T1, Tn...> : std::conjunction<std::conjunction<ArithmeticChecker<Tn...>>, std::is_arithmetic<T1>> {
            };
            template <class T1>
            struct ArithmeticChecker<T1> : std::is_arithmetic<T1> {
            };
            
            template <class ... Tn>
            constexpr bool ArithmeticCheckerV = ArithmeticChecker<Tn...>::value; 
            template <class ... Tn>
            using UseIfArithmetic = std::enable_if_t<ArithmeticCheckerV<Tn...>>;

            static constexpr long double EPSILON = 0.000001;    
            static constexpr long double PI = 3.141592653589793238462643383279502884L;

            template <class T, class K, typename std::enable_if_t< std::is_floating_point<std::common_type_t<T, K>>::value, int> = 0>
            constexpr bool equal(T a, K b) {
                return std::abs(static_cast <std::common_type_t<T, K>> (a) - static_cast <std::common_type_t<T, K>> (b)) < EPSILON;
            }
    
            template <class T, class K, typename std::enable_if_t<!std::is_floating_point<std::common_type_t<T, K>>::value, int> = 0>
            constexpr bool equal(T a, K b) {
                return static_cast <std::common_type_t<T, K>> (a) == static_cast <std::common_type_t<T, K>> (b);
            }
            template <class T, class K>
            constexpr bool almostEqual(T a, K b) {
                return equal(a, b);
            }
            template <class T, typename = UseIfArithmetic<T>>
            constexpr T lerp(T const& a, T const& b, float const& f) {
                return a * (1.0f - f) + b * f;
            }
        }
    }