color.hpp

// Copyright Take Vos 2021.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
 
#pragma once
 
#include "../rapid/numeric_array.hpp"
 
namespace hi::inline v1 {
 
class color {
public:
    constexpr color(color const &) noexcept = default;
    constexpr color(color &&) noexcept = default;
    constexpr color &operator=(color const &) noexcept = default;
    constexpr color &operator=(color &&) noexcept = default;
 
    [[nodiscard]] constexpr explicit color(f16x4 const &other) noexcept : _v(other)
    {
        hi_axiom(holds_invariant());
    }
 
    [[nodiscard]] constexpr explicit color(f32x4 const &other) noexcept : color(static_cast<f16x4>(other)) {}
 
    [[nodiscard]] constexpr explicit operator f16x4() const noexcept
    {
        return _v;
    }
 
    [[nodiscard]] constexpr explicit operator f32x4() const noexcept
    {
        return static_cast<f32x4>(_v);
    }
 
    [[nodiscard]] constexpr color(float r, float g, float b, float a = 1.0f) noexcept : color(f32x4{r, g, b, a}) {}
 
    [[nodiscard]] constexpr color() noexcept : color(f32x4{}) {}
 
    [[nodiscard]] static constexpr color transparent() noexcept
    {
        return {0.0f, 0.0f, 0.0f, 0.0f};
    }
 
    [[nodiscard]] static constexpr color white() noexcept
    {
        return {1.0f, 1.0f, 1.0f, 1.0f};
    }
 
    [[nodiscard]] static constexpr color black() noexcept
    {
        return {0.0f, 0.0f, 0.0f, 1.0f};
    }
 
    [[nodiscard]] constexpr float16 &r() noexcept
    {
        return _v.x();
    }
 
    [[nodiscard]] constexpr float16 &g() noexcept
    {
        return _v.y();
    }
 
    [[nodiscard]] constexpr float16 &b() noexcept
    {
        return _v.z();
    }
 
    [[nodiscard]] constexpr float16 &a() noexcept
    {
        return _v.w();
    }
 
    [[nodiscard]] constexpr float16 const &r() const noexcept
    {
        return _v.x();
    }
 
    [[nodiscard]] constexpr float16 const &g() const noexcept
    {
        return _v.y();
    }
 
    [[nodiscard]] constexpr float16 const &b() const noexcept
    {
        return _v.z();
    }
 
    [[nodiscard]] constexpr float16 const &a() const noexcept
    {
        return _v.w();
    }
 
    [[nodiscard]] constexpr bool holds_invariant() const noexcept
    {
        return _v.w() >= 0.0 && _v.w() <= 1.0;
    }
 
    [[nodiscard]] constexpr friend bool operator==(color const &lhs, color const &rhs) noexcept = default;
 
    [[nodiscard]] constexpr friend color operator*(color const &lhs, color const &rhs) noexcept
    {
        return color{lhs._v * rhs._v};
    }
 
    [[nodiscard]] constexpr friend color composit(color const &lhs, color const &rhs) noexcept
    {
        return color{composit(lhs._v, rhs._v)};
    }
 
    [[nodiscard]] constexpr friend color desaturate(color const &rhs) noexcept
    {
        auto rhs_ = f32x4{rhs};
 
        auto Y = 0.2126f * rhs_.r() + 0.7152f * rhs_.g() + 0.0722f * rhs_.b();
 
        return color{Y, Y, Y, rhs_.a()};
    }
 
private:
    f16x4 _v;
};
 
} // namespace hi::inline v1