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  /** @file matrix4x4.h
   *  @brief 4x4 matrix structure, including operators when compiling in C++
   */
  #pragma once
  #ifndef AI_MATRIX4X4_H_INC
  #define AI_MATRIX4X4_H_INC
  
  #include "ai_vector3.h"
  #include "ai_pushpack1.h"
  #include "ai_defs.h"
  
  #ifdef __cplusplus
  
  template<typename TReal> class aiMatrix3x3t;
  template<typename TReal> class aiQuaterniont;
  
  // ---------------------------------------------------------------------------
  /** @brief Represents a row-major 4x4 matrix, use this for homogeneous
   *   coordinates.
   *
   *  There's much confusion about matrix layouts (column vs. row order).
   *  This is *always* a row-major matrix. Not even with the
   *  #aiProcess_ConvertToLeftHanded flag, which absolutely does not affect
   *  matrix order - it just affects the handedness of the coordinate system
   *  defined thereby.
   */
  template<typename TReal>
  class aiMatrix4x4t
  {
  public:
  
      /** set to identity */
      aiMatrix4x4t ();
  
      /** construction from single values */
      aiMatrix4x4t (  TReal _a1, TReal _a2, TReal _a3, TReal _a4,
                      TReal _b1, TReal _b2, TReal _b3, TReal _b4,
                      TReal _c1, TReal _c2, TReal _c3, TReal _c4,
                      TReal _d1, TReal _d2, TReal _d3, TReal _d4);
  
  
      /** construction from 3x3 matrix, remaining elements are set to identity */
      explicit aiMatrix4x4t( const aiMatrix3x3t<TReal>& m);
  
      /** construction from position, rotation and scaling components
       * @param scaling The scaling for the x,y,z axes
       * @param rotation The rotation as a hamilton quaternion
       * @param position The position for the x,y,z axes
       */
      aiMatrix4x4t(const aiVector3t<TReal>& scaling, const aiQuaterniont<TReal>& rotation,
          const aiVector3t<TReal>& position);
  
  public:
  
      // array access operators
      TReal* operator[]       (unsigned int p_iIndex);
      const TReal* operator[] (unsigned int p_iIndex) const;
  
      // comparison operators
      bool operator== (const aiMatrix4x4t& m) const;
      bool operator!= (const aiMatrix4x4t& m) const;
  
      bool Equal(const aiMatrix4x4t& m, TReal epsilon = 1e-6) const;
  
      // matrix multiplication.
      aiMatrix4x4t& operator *= (const aiMatrix4x4t& m);
      aiMatrix4x4t  operator *  (const aiMatrix4x4t& m) const;
  
      template <typename TOther>
      operator aiMatrix4x4t<TOther> () const;
  
  public:
  
      // -------------------------------------------------------------------
      /** @brief Transpose the matrix */
      aiMatrix4x4t& Transpose();
  
      // -------------------------------------------------------------------
      /** @brief Invert the matrix.
       *  If the matrix is not invertible all elements are set to qnan.
       *  Beware, use (f != f) to check whether a TReal f is qnan.
       */
      aiMatrix4x4t& Inverse();
      TReal Determinant() const;
  
  
      // -------------------------------------------------------------------
      /** @brief Returns true of the matrix is the identity matrix.
       *  The check is performed against a not so small epsilon.
       */
      inline bool IsIdentity() const;
  
      // -------------------------------------------------------------------
      /** @brief Decompose a trafo matrix into its original components
       *  @param scaling Receives the output scaling for the x,y,z axes
       *  @param rotation Receives the output rotation as a hamilton
       *   quaternion
       *  @param position Receives the output position for the x,y,z axes
       */
      void Decompose (aiVector3t<TReal>& scaling, aiQuaterniont<TReal>& rotation,
          aiVector3t<TReal>& position) const;
  
      // -------------------------------------------------------------------
      /** @brief Decompose a trafo matrix with no scaling into its
       *    original components
       *  @param rotation Receives the output rotation as a hamilton
       *    quaternion
       *  @param position Receives the output position for the x,y,z axes
       */
      void DecomposeNoScaling (aiQuaterniont<TReal>& rotation,
          aiVector3t<TReal>& position) const;
  
  
      // -------------------------------------------------------------------
      /** @brief Creates a trafo matrix from a set of euler angles
       *  @param x Rotation angle for the x-axis, in radians
       *  @param y Rotation angle for the y-axis, in radians
       *  @param z Rotation angle for the z-axis, in radians
       */
      aiMatrix4x4t& FromEulerAnglesXYZ(TReal x, TReal y, TReal z);
      aiMatrix4x4t& FromEulerAnglesXYZ(const aiVector3t<TReal>& blubb);
  
  public:
      // -------------------------------------------------------------------
      /** @brief Returns a rotation matrix for a rotation around the x axis
       *  @param a Rotation angle, in radians
       *  @param out Receives the output matrix
       *  @return Reference to the output matrix
       */
      static aiMatrix4x4t& RotationX(TReal a, aiMatrix4x4t& out);
  
      // -------------------------------------------------------------------
      /** @brief Returns a rotation matrix for a rotation around the y axis
       *  @param a Rotation angle, in radians
       *  @param out Receives the output matrix
       *  @return Reference to the output matrix
       */
      static aiMatrix4x4t& RotationY(TReal a, aiMatrix4x4t& out);
  
      // -------------------------------------------------------------------
      /** @brief Returns a rotation matrix for a rotation around the z axis
       *  @param a Rotation angle, in radians
       *  @param out Receives the output matrix
       *  @return Reference to the output matrix
       */
      static aiMatrix4x4t& RotationZ(TReal a, aiMatrix4x4t& out);
  
      // -------------------------------------------------------------------
      /** Returns a rotation matrix for a rotation around an arbitrary axis.
       *  @param a Rotation angle, in radians
       *  @param axis Rotation axis, should be a normalized vector.
       *  @param out Receives the output matrix
       *  @return Reference to the output matrix
       */
      static aiMatrix4x4t& Rotation(TReal a, const aiVector3t<TReal>& axis,
          aiMatrix4x4t& out);
  
      // -------------------------------------------------------------------
      /** @brief Returns a translation matrix
       *  @param v Translation vector
       *  @param out Receives the output matrix
       *  @return Reference to the output matrix
       */
      static aiMatrix4x4t& Translation( const aiVector3t<TReal>& v, aiMatrix4x4t& out);
  
      // -------------------------------------------------------------------
      /** @brief Returns a scaling matrix
       *  @param v Scaling vector
       *  @param out Receives the output matrix
       *  @return Reference to the output matrix
       */
      static aiMatrix4x4t& Scaling( const aiVector3t<TReal>& v, aiMatrix4x4t& out);
  
      // -------------------------------------------------------------------
      /** @brief A function for creating a rotation matrix that rotates a
       *  vector called "from" into another vector called "to".
       * Input : from[3], to[3] which both must be *normalized* non-zero vectors
       * Output: mtx[3][3] -- a 3x3 matrix in column-major form
       * Authors: Tomas Mueller, John Hughes
       *          "Efficiently Building a Matrix to Rotate One Vector to Another"
       *          Journal of Graphics Tools, 4(4):1-4, 1999
       */
      static aiMatrix4x4t& FromToMatrix(const aiVector3t<TReal>& from,
          const aiVector3t<TReal>& to, aiMatrix4x4t& out);
  
  public:
      TReal a1, a2, a3, a4;
      TReal b1, b2, b3, b4;
      TReal c1, c2, c3, c4;
      TReal d1, d2, d3, d4;
  } PACK_STRUCT;
  
  typedef aiMatrix4x4t<ai_real> aiMatrix4x4;
  
  #else
  
  struct aiMatrix4x4 {
      ai_real a1, a2, a3, a4;
      ai_real b1, b2, b3, b4;
      ai_real c1, c2, c3, c4;
      ai_real d1, d2, d3, d4;
  } PACK_STRUCT;
  
  
  #endif // __cplusplus
  
  #include "ai_poppack1.h"
  
  #endif // AI_MATRIX4X4_H_INC
  