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/** @file matrix3x3.h
 *  @brief Definition of a 3x3 matrix, including operators when compiling in C++
 */
#ifndef AI_MATRIX3x3_H_INC
#define AI_MATRIX3x3_H_INC

#include "./Compiler/pushpack1.h"

#ifdef __cplusplus

template <typename T> class aiMatrix4x4t;
template <typename T> class aiVector2t;

// ---------------------------------------------------------------------------
/** @brief Represents a row-major 3x3 matrix
 *
 *  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 aiMatrix3x3t
{
public:

	aiMatrix3x3t () :	
		a1(static_cast<TReal>(1.0f)), a2(), a3(), 
		b1(), b2(static_cast<TReal>(1.0f)), b3(), 
		c1(), c2(), c3(static_cast<TReal>(1.0f)) {}

	aiMatrix3x3t (	TReal _a1, TReal _a2, TReal _a3,
					TReal _b1, TReal _b2, TReal _b3,
					TReal _c1, TReal _c2, TReal _c3) :	
		a1(_a1), a2(_a2), a3(_a3), 
		b1(_b1), b2(_b2), b3(_b3), 
		c1(_c1), c2(_c2), c3(_c3)
	{}

public:

	// matrix multiplication. 
	aiMatrix3x3t& operator *= (const aiMatrix3x3t& m);
	aiMatrix3x3t  operator  * (const aiMatrix3x3t& m) const;

	// array access operators
	TReal* operator[]       (unsigned int p_iIndex);
	const TReal* operator[] (unsigned int p_iIndex) const;

	// comparison operators
	bool operator== (const aiMatrix4x4t<TReal>& m) const;
	bool operator!= (const aiMatrix4x4t<TReal>& m) const;

	bool Equal(const aiMatrix4x4t<TReal>& m, TReal epsilon = 1e-6) const;

	template <typename TOther>
	operator aiMatrix3x3t<TOther> () const;

public:

	// -------------------------------------------------------------------
	/** @brief Construction from a 4x4 matrix. The remaining parts 
	 *  of the matrix are ignored.
	 */
	explicit aiMatrix3x3t( const aiMatrix4x4t<TReal>& pMatrix);

	// -------------------------------------------------------------------
	/** @brief Transpose the matrix
	 */
	aiMatrix3x3t& 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.
	 */
	aiMatrix3x3t& Inverse();
	TReal Determinant() const;

public:
	// -------------------------------------------------------------------
	/** @brief Returns a rotation matrix for a rotation around z
	 *  @param a Rotation angle, in radians
	 *  @param out Receives the output matrix
	 *  @return Reference to the output matrix
	 */
	static aiMatrix3x3t& RotationZ(TReal a, aiMatrix3x3t& out);

	// -------------------------------------------------------------------
	/** @brief Returns a rotation matrix for a rotation around
	 *    an arbitrary axis.
	 *
	 *  @param a Rotation angle, in radians
	 *  @param axis Axis to rotate around
	 *  @param out To be filled
	 */
	static aiMatrix3x3t& Rotation( TReal a, 
		const aiVector3t<TReal>& axis, aiMatrix3x3t& out);

	// -------------------------------------------------------------------
	/** @brief Returns a translation matrix 
	 *  @param v Translation vector
	 *  @param out Receives the output matrix
	 *  @return Reference to the output matrix
	 */
	static aiMatrix3x3t& Translation( const aiVector2t<TReal>& v, aiMatrix3x3t& 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 colum-major form
	 * Authors: Tomas Möller, John Hughes
	 *          "Efficiently Building a Matrix to Rotate One Vector to Another"
	 *          Journal of Graphics Tools, 4(4):1-4, 1999
	 */
	static aiMatrix3x3t& FromToMatrix(const aiVector3t<TReal>& from, 
		const aiVector3t<TReal>& to, aiMatrix3x3t& out);

public:


	TReal a1, a2, a3;
	TReal b1, b2, b3;
	TReal c1, c2, c3;
} PACK_STRUCT;

typedef aiMatrix3x3t<float> aiMatrix3x3;

#else

struct aiMatrix3x3 {

	float a1, a2, a3;
	float b1, b2, b3;
	float c1, c2, c3;
} PACK_STRUCT;

#endif

#include "./Compiler/poppack1.h"

#endif // AI_MATRIX3x3_H_INC
