vec3.h

#pragma once
 
/* <editor-fold desc="MIT License">
 
Copyright(c) 2018 Robert Osfield
 
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
</editor-fold> */
 
// we can't implement the anonymous union/structs combination without causing warnings, so disable them for just this header
#if defined(__GNUC__)
#    pragma GCC diagnostic push
#    pragma GCC diagnostic ignored "-Wpedantic"
#endif
#if defined(__clang__)
#    pragma clang diagnostic push
#    pragma clang diagnostic ignored "-Wgnu-anonymous-struct"
#    pragma clang diagnostic ignored "-Wnested-anon-types"
#endif
 
#include <vsg/maths/vec2.h>
 
namespace vsg
{
 
    template<typename T>
    struct t_vec3
    {
        using value_type = T;
 
        union
        {
            value_type value[3];
            struct
            {
                value_type x, y, z;
            };
            struct
            {
                value_type r, g, b;
            };
            struct
            {
                value_type s, t, p;
            };
        };
 
        constexpr t_vec3() :
            value{} {}
        constexpr t_vec3(const t_vec3& v) :
            value{v.x, v.y, v.z} {}
        constexpr t_vec3& operator=(const t_vec3&) = default;
        constexpr t_vec3(value_type in_x, value_type in_y, value_type in_z) :
            value{in_x, in_y, in_z} {}
 
        template<typename R>
        constexpr t_vec3(const t_vec2<R>& v, value_type in_z) :
            value{v.x, v.y, in_z} {}
 
        template<typename R>
        constexpr explicit t_vec3(const t_vec3<R>& v) :
            value{static_cast<T>(v.x), static_cast<T>(v.y), static_cast<T>(v.z)} {}
 
        constexpr std::size_t size() const { return 3; }
 
        value_type& operator[](std::size_t i) { return value[i]; }
        value_type operator[](std::size_t i) const { return value[i]; }
 
        template<typename R>
        t_vec3& operator=(const t_vec3<R>& rhs)
        {
            value[0] = static_cast<value_type>(rhs[0]);
            value[1] = static_cast<value_type>(rhs[1]);
            value[2] = static_cast<value_type>(rhs[2]);
            return *this;
        }
 
        T* data() { return value; }
        const T* data() const { return value; }
 
        void set(value_type in_x, value_type in_y, value_type in_z)
        {
            x = in_x;
            y = in_y;
            z = in_z;
        }
 
        inline t_vec3& operator+=(const t_vec3& rhs)
        {
            value[0] += rhs.value[0];
            value[1] += rhs.value[1];
            value[2] += rhs.value[2];
            return *this;
        }
 
        inline t_vec3& operator-=(const t_vec3& rhs)
        {
            value[0] -= rhs.value[0];
            value[1] -= rhs.value[1];
            value[2] -= rhs.value[2];
            return *this;
        }
 
        inline t_vec3& operator*=(value_type rhs)
        {
            value[0] *= rhs;
            value[1] *= rhs;
            value[2] *= rhs;
            return *this;
        }
 
        inline t_vec3& operator*=(const t_vec3& rhs)
        {
            value[0] *= rhs.value[0];
            value[1] *= rhs.value[1];
            value[2] *= rhs.value[2];
            return *this;
        }
 
        inline t_vec3& operator/=(value_type rhs)
        {
            if constexpr (std::is_floating_point_v<value_type>)
            {
                value_type inv = static_cast<value_type>(1.0) / rhs;
                value[0] *= inv;
                value[1] *= inv;
                value[2] *= inv;
            }
            else
            {
                value[0] /= rhs;
                value[1] /= rhs;
                value[2] /= rhs;
            }
            return *this;
        }
 
        explicit operator bool() const noexcept { return value[0] != 0.0 || value[1] != 0.0 || value[2] != 0.0; }
    };
 
    using vec3 = t_vec3<float>;      // float 3D vector
    using dvec3 = t_vec3<double>;    // double 3D vector
    using bvec3 = t_vec3<int8_t>;    // signed 8 bit integer 3D vector
    using svec3 = t_vec3<int16_t>;   //  signed 16 bit integer 3D vector
    using ivec3 = t_vec3<int32_t>;   //  signed 32 bit integer 3D vector
    using ubvec3 = t_vec3<uint8_t>;  //  unsigned 8 bit integer 3D vector
    using usvec3 = t_vec3<uint16_t>; //  unsigned 16 bit integer 3D vector
    using uivec3 = t_vec3<uint32_t>; //  unsigned 32 bit integer 3D vector
 
    VSG_type_name(vsg::vec3);
    VSG_type_name(vsg::dvec3);
    VSG_type_name(vsg::bvec3);
    VSG_type_name(vsg::svec3);
    VSG_type_name(vsg::ivec3);
    VSG_type_name(vsg::ubvec3);
    VSG_type_name(vsg::usvec3);
    VSG_type_name(vsg::uivec3);
 
    template<typename T>
    constexpr bool operator==(const t_vec3<T>& lhs, const t_vec3<T>& rhs)
    {
        return lhs[0] == rhs[0] && lhs[1] == rhs[1] && lhs[2] == rhs[2];
    }
 
    template<typename T>
    constexpr bool operator!=(const t_vec3<T>& lhs, const t_vec3<T>& rhs)
    {
        return lhs[0] != rhs[0] || lhs[1] != rhs[1] || lhs[2] != rhs[2];
    }
 
    template<typename T>
    constexpr bool operator<(const t_vec3<T>& lhs, const t_vec3<T>& rhs)
    {
        if (lhs[0] < rhs[0]) return true;
        if (lhs[0] > rhs[0]) return false;
        if (lhs[1] < rhs[1]) return true;
        if (lhs[1] > rhs[1]) return false;
        return lhs[2] < rhs[2];
    }
 
    template<typename T>
    constexpr t_vec3<T> operator-(const t_vec3<T>& lhs, const t_vec3<T>& rhs)
    {
        return t_vec3<T>(lhs[0] - rhs[0], lhs[1] - rhs[1], lhs[2] - rhs[2]);
    }
 
    template<typename T>
    constexpr t_vec3<T> operator-(const t_vec3<T>& v)
    {
        return t_vec3<T>(-v[0], -v[1], -v[2]);
    }
 
    template<typename T>
    constexpr t_vec3<T> operator+(const t_vec3<T>& lhs, const t_vec3<T>& rhs)
    {
        return t_vec3<T>(lhs[0] + rhs[0], lhs[1] + rhs[1], lhs[2] + rhs[2]);
    }
 
    template<typename T>
    constexpr t_vec3<T> operator*(const t_vec3<T>& lhs, T rhs)
    {
        return t_vec3<T>(lhs[0] * rhs, lhs[1] * rhs, lhs[2] * rhs);
    }
 
    template<typename T>
    constexpr t_vec3<T> operator*(const t_vec3<T>& lhs, const t_vec3<T>& rhs)
    {
        return t_vec3<T>(lhs[0] * rhs[0], lhs[1] * rhs[1], lhs[2] * rhs[2]);
    }
 
    template<typename T>
    constexpr t_vec3<T> operator/(const t_vec3<T>& lhs, T rhs)
    {
        if constexpr (std::is_floating_point_v<T>)
        {
            T inv = static_cast<T>(1.0) / rhs;
            return t_vec3<T>(lhs[0] * inv, lhs[1] * inv, lhs[2] * inv);
        }
        else
        {
            return t_vec3<T>(lhs[0] / rhs, lhs[1] / rhs, lhs[2] / rhs);
        }
    }
 
    template<typename T>
    constexpr T length(const t_vec3<T>& v)
    {
        return std::sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
    }
 
    template<typename T>
    constexpr T length2(const t_vec3<T>& v)
    {
        return v[0] * v[0] + v[1] * v[1] + v[2] * v[2];
    }
 
    template<typename T>
    constexpr t_vec3<T> normalize(const t_vec3<T>& v)
    {
        return v / length(v);
    }
 
    template<typename T>
    constexpr T dot(const t_vec3<T>& lhs, const t_vec3<T>& rhs)
    {
        return lhs[0] * rhs[0] + lhs[1] * rhs[1] + lhs[2] * rhs[2];
    }
 
    template<typename T>
    constexpr t_vec3<T> cross(const t_vec3<T>& lhs, const t_vec3<T>& rhs)
    {
        return t_vec3<T>(lhs[1] * rhs[2] - rhs[1] * lhs[2],
                         lhs[2] * rhs[0] - rhs[2] * lhs[0],
                         lhs[0] * rhs[1] - rhs[0] * lhs[1]);
    }
 
    template<typename T>
    constexpr t_vec3<T> mix(const t_vec3<T>& start, const t_vec3<T>& end, T r)
    {
        T one_minus_r = 1 - r;
        return t_vec3<T>(start[0] * one_minus_r + end[0] * r,
                         start[1] * one_minus_r + end[1] * r,
                         start[2] * one_minus_r + end[2] * r);
    }
 
    template<typename T>
    constexpr t_vec3<T> orthogonal(const t_vec3<T>& v)
    {
        // use the cross product against the axis which is the most orthogonal to the input vector.
        auto abs_x = fabs(v.x);
        auto abs_y = fabs(v.y);
        auto abs_z = fabs(v.z);
        if (abs_x < abs_y)
        {
            if (abs_x < abs_z) return {0.0, v.z, -v.y}; // v.x shortest, use cross with x axis
        }
        else if (abs_y < abs_z)
        {
            return {-v.z, 0.0, v.x}; // v.y shortest, use cross with y axis
        }
        return {v.y, -v.x, 0.0}; // v.z shortest, use cross with z axis
    }
 
} // namespace vsg
 
#if defined(__clang__)
#    pragma clang diagnostic pop
#endif
#if defined(__GNUC__)
#    pragma GCC diagnostic pop
#endif