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Open Asset Import Library (assimp)
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*/

/** @file quaternion.h
 *  @brief Quaternion structure, including operators when compiling in C++
 */
#pragma once
#ifndef AI_QUATERNION_H_INC
#define AI_QUATERNION_H_INC

#include <assimp/defs.h>

#ifdef __cplusplus

#ifdef __GNUC__
#   pragma GCC system_header
#endif

// Forward declarations
template <typename TReal> class aiVector3t;
template <typename TReal> class aiMatrix3x3t;
template <typename TReal> class aiMatrix4x4t;

// ---------------------------------------------------------------------------
/**
 *  @brief  This class represents a quaternion as a 4D vector.
 */
template <typename TReal>
class aiQuaterniont {
public:
    aiQuaterniont() AI_NO_EXCEPT : w(1.0), x(), y(), z() {}
    aiQuaterniont(TReal pw, TReal px, TReal py, TReal pz)
        : w(pw), x(px), y(py), z(pz) {}

    /**
     *  @brief  Construct from rotation matrix. Result is undefined if the matrix is not orthonormal.
     */
    explicit aiQuaterniont( const aiMatrix3x3t<TReal>& pRotMatrix);

    /** Construct from euler angles */
    aiQuaterniont( TReal roty, TReal rotz, TReal rotx);

    /** Construct from an axis-angle pair */
    aiQuaterniont( aiVector3t<TReal> axis, TReal angle);

    /** Construct from a normalized quaternion stored in a vec3 */
    explicit aiQuaterniont( aiVector3t<TReal> normalized);

    /** Returns a matrix representation of the quaternion */
    aiMatrix3x3t<TReal> GetMatrix() const;

    bool operator== (const aiQuaterniont& o) const;
    bool operator!= (const aiQuaterniont& o) const;

    // transform vector by matrix
    aiQuaterniont& operator *= (const aiMatrix4x4t<TReal>& mat);

    bool Equal(const aiQuaterniont &o, TReal epsilon = ai_epsilon) const;

    /**
     *  @brief  Will normalize the quaternion representation.
     */
    aiQuaterniont& Normalize();

    /**
     *  @brief  Will compute the quaternion conjugate. The result will be stored in the instance.
     */
    aiQuaterniont& Conjugate();

    /**
     *  @brief  Rotate a point by this quaternion
     */
    aiVector3t<TReal> Rotate(const aiVector3t<TReal>& in) const;

    /**
     *  @brief Multiply two quaternions
     *  @param  two   The other quaternion.
     *  @return The result of the multiplication.
     */
    aiQuaterniont operator * (const aiQuaterniont& two) const;

    /**
     * @brief Performs a spherical interpolation between two quaternions and writes the result into the third.
     * @param pOut Target object to received the interpolated rotation.
     * @param pStart Start rotation of the interpolation at factor == 0.
     * @param pEnd End rotation, factor == 1.
     * @param pFactor Interpolation factor between 0 and 1. Values outside of this range yield undefined results.
     */
    static void Interpolate( aiQuaterniont& pOut, const aiQuaterniont& pStart,
        const aiQuaterniont& pEnd, TReal pFactor);

    //! w,x,y,z components of the quaternion
    TReal w, x, y, z;
} ;

using aiQuaternion = aiQuaterniont<ai_real>;

#else

struct aiQuaternion {
    ai_real w, x, y, z;
};

#endif

#endif // AI_QUATERNION_H_INC
