added files

include/omath/linear_algebra/quaternion.hpp

@@ -0,0 +1,219 @@
+//
+// Created by vlad on 3/1/2026.
+//
+#pragma once
+
+#include "omath/linear_algebra/mat.hpp"
+#include "omath/linear_algebra/vector3.hpp"
+#include <array>
+#include <cmath>
+#include <format>
+
+namespace omath
+{
+    template<class Type>
+    requires std::is_arithmetic_v<Type>
+    class Quaternion
+    {
+    public:
+        using ContainedType = Type;
+
+        Type x = static_cast<Type>(0);
+        Type y = static_cast<Type>(0);
+        Type z = static_cast<Type>(0);
+        Type w = static_cast<Type>(1);  // identity quaternion
+
+        constexpr Quaternion() noexcept = default;
+
+        constexpr Quaternion(const Type& x, const Type& y, const Type& z, const Type& w) noexcept
+            : x(x), y(y), z(z), w(w)
+        {
+        }
+
+        // Factory: build from a normalized axis and an angle in radians
+        [[nodiscard]]
+        static Quaternion from_axis_angle(const Vector3<Type>& axis, const Type& angle_rad) noexcept
+        {
+            const Type half = angle_rad / static_cast<Type>(2);
+            const Type s = std::sin(half);
+            return {axis.x * s, axis.y * s, axis.z * s, std::cos(half)};
+        }
+
+        [[nodiscard]] constexpr bool operator==(const Quaternion& other) const noexcept
+        {
+            return x == other.x && y == other.y && z == other.z && w == other.w;
+        }
+
+        [[nodiscard]] constexpr bool operator!=(const Quaternion& other) const noexcept
+        {
+            return !(*this == other);
+        }
+
+        // Hamilton product: this * other
+        [[nodiscard]] constexpr Quaternion operator*(const Quaternion& other) const noexcept
+        {
+            return {
+                w * other.x + x * other.w + y * other.z - z * other.y,
+                w * other.y - x * other.z + y * other.w + z * other.x,
+                w * other.z + x * other.y - y * other.x + z * other.w,
+                w * other.w - x * other.x - y * other.y - z * other.z,
+            };
+        }
+
+        constexpr Quaternion& operator*=(const Quaternion& other) noexcept
+        {
+            return *this = *this * other;
+        }
+
+        [[nodiscard]] constexpr Quaternion operator*(const Type& scalar) const noexcept
+        {
+            return {x * scalar, y * scalar, z * scalar, w * scalar};
+        }
+
+        constexpr Quaternion& operator*=(const Type& scalar) noexcept
+        {
+            x *= scalar;
+            y *= scalar;
+            z *= scalar;
+            w *= scalar;
+            return *this;
+        }
+
+        [[nodiscard]] constexpr Quaternion operator+(const Quaternion& other) const noexcept
+        {
+            return {x + other.x, y + other.y, z + other.z, w + other.w};
+        }
+
+        constexpr Quaternion& operator+=(const Quaternion& other) noexcept
+        {
+            x += other.x;
+            y += other.y;
+            z += other.z;
+            w += other.w;
+            return *this;
+        }
+
+        [[nodiscard]] constexpr Quaternion operator-() const noexcept
+        {
+            return {-x, -y, -z, -w};
+        }
+
+        // Conjugate: negates the vector part (x, y, z)
+        [[nodiscard]] constexpr Quaternion conjugate() const noexcept
+        {
+            return {-x, -y, -z, w};
+        }
+
+        [[nodiscard]] constexpr Type dot(const Quaternion& other) const noexcept
+        {
+            return x * other.x + y * other.y + z * other.z + w * other.w;
+        }
+
+        [[nodiscard]] constexpr Type length_sqr() const noexcept
+        {
+            return x * x + y * y + z * z + w * w;
+        }
+
+#ifndef _MSC_VER
+        [[nodiscard]] constexpr Type length() const noexcept
+        {
+            return std::sqrt(length_sqr());
+        }
+
+        [[nodiscard]] constexpr Quaternion normalized() const noexcept
+        {
+            const Type len = length();
+            return len != static_cast<Type>(0) ? *this * (static_cast<Type>(1) / len) : *this;
+        }
+#else
+        [[nodiscard]] Type length() const noexcept
+        {
+            return std::sqrt(length_sqr());
+        }
+
+        [[nodiscard]] Quaternion normalized() const noexcept
+        {
+            const Type len = length();
+            return len != static_cast<Type>(0) ? *this * (static_cast<Type>(1) / len) : *this;
+        }
+#endif
+
+        // Inverse: q* / |q|^2  (for unit quaternions inverse == conjugate)
+        [[nodiscard]] constexpr Quaternion inverse() const noexcept
+        {
+            return conjugate() * (static_cast<Type>(1) / length_sqr());
+        }
+
+        // Rotate a 3D vector: v' = q * pure(v) * q^-1
+        // Computed via Rodrigues' formula to avoid full quaternion product overhead
+        [[nodiscard]] constexpr Vector3<Type> rotate(const Vector3<Type>& v) const noexcept
+        {
+            const Vector3<Type> q_vec{x, y, z};
+            const Vector3<Type> cross = q_vec.cross(v);
+            return v + cross * (static_cast<Type>(2) * w) + q_vec.cross(cross) * static_cast<Type>(2);
+        }
+
+        // 3x3 rotation matrix from this (unit) quaternion
+        [[nodiscard]] constexpr Mat<3, 3, Type> to_rotation_matrix3() const noexcept
+        {
+            const Type xx = x * x, yy = y * y, zz = z * z;
+            const Type xy = x * y, xz = x * z, yz = y * z;
+            const Type wx = w * x, wy = w * y, wz = w * z;
+            const Type one = static_cast<Type>(1);
+            const Type two = static_cast<Type>(2);
+
+            return {
+                {one - two * (yy + zz), two * (xy - wz),       two * (xz + wy)      },
+                {two * (xy + wz),       one - two * (xx + zz), two * (yz - wx)      },
+                {two * (xz - wy),       two * (yz + wx),       one - two * (xx + yy)},
+            };
+        }
+
+        // 4x4 rotation matrix (with homogeneous row/column)
+        [[nodiscard]] constexpr Mat<4, 4, Type> to_rotation_matrix4() const noexcept
+        {
+            const Type xx = x * x, yy = y * y, zz = z * z;
+            const Type xy = x * y, xz = x * z, yz = y * z;
+            const Type wx = w * x, wy = w * y, wz = w * z;
+            const Type one = static_cast<Type>(1);
+            const Type two = static_cast<Type>(2);
+            const Type zero = static_cast<Type>(0);
+
+            return {
+                {one - two * (yy + zz), two * (xy - wz),       two * (xz + wy),       zero},
+                {two * (xy + wz),       one - two * (xx + zz), two * (yz - wx),       zero},
+                {two * (xz - wy),       two * (yz + wx),       one - two * (xx + yy), zero},
+                {zero,                  zero,                   zero,                  one },
+            };
+        }
+
+        [[nodiscard]] constexpr std::array<Type, 4> as_array() const noexcept
+        {
+            return {x, y, z, w};
+        }
+    };
+} // namespace omath
+
+template<class Type>
+struct std::formatter<omath::Quaternion<Type>> // NOLINT(*-dcl58-cpp)
+{
+    [[nodiscard]]
+    static constexpr auto parse(std::format_parse_context& ctx)
+    {
+        return ctx.begin();
+    }
+
+    template<class FormatContext>
+    [[nodiscard]]
+    static auto format(const omath::Quaternion<Type>& q, FormatContext& ctx)
+    {
+        if constexpr (std::is_same_v<typename FormatContext::char_type, char>)
+            return std::format_to(ctx.out(), "[{}, {}, {}, {}]", q.x, q.y, q.z, q.w);
+
+        if constexpr (std::is_same_v<typename FormatContext::char_type, wchar_t>)
+            return std::format_to(ctx.out(), L"[{}, {}, {}, {}]", q.x, q.y, q.z, q.w);
+
+        if constexpr (std::is_same_v<typename FormatContext::char_type, char8_t>)
+            return std::format_to(ctx.out(), u8"[{}, {}, {}, {}]", q.x, q.y, q.z, q.w);
+    }
+};

include/omath/omath.hpp

@@ -17,6 +17,9 @@
 // Matrix classes
 #include "omath/linear_algebra/mat.hpp"
 
+// Quaternion
+#include "omath/linear_algebra/quaternion.hpp"
+
 // Color functionality
 #include "omath/utility/color.hpp"