matrix4d.h

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// matrix4.template.h file to make changes.

#ifndef GF_MATRIX4D_H
#define GF_MATRIX4D_H

/// \file gf/matrix4d.h
/// \ingroup group_gf_LinearAlgebra

#include "pxr/base/gf/matrixData.h"
#include "pxr/base/gf/vec4d.h"
#include "pxr/base/gf/traits.h"
#include "pxr/base/gf/homogeneous.h"
#include "pxr/base/gf/limits.h"
#include "pxr/base/gf/math.h"
#include "pxr/base/gf/vec3d.h"

#include <boost/functional/hash.hpp>

#include <iosfwd>
#include <vector>

template <>
struct GfIsGfMatrix<class GfMatrix4d> { static const bool value = true; };

class GfMatrix4d;
class GfMatrix4f;
class GfRotation;
class GfMatrix3d;

/// \class GfMatrix4d
/// \ingroup group_gf_LinearAlgebra
///
/// Stores a 4x4 matrix of \c double elements. A basic type.
///
/// Matrices are defined to be in row-major order, so <c>matrix[i][j]</c>
/// indexes the element in the \e i th row and the \e j th column.
///
/// <h3>3D Transformations</h3>
///
/// The following methods interpret a GfMatrix4d as a 3D
/// transformation: SetRotate(), SetScale(), SetTranslate(), SetLookAt(),
/// Factor(), ExtractTranslation(), ExtractRotation(), Transform(), TransformDir().
/// By convention, vectors are treated primarily as row vectors,
/// implying the following:
/// \li Transformation matrices are organized to deal with row
///        vectors, not column vectors. For example, the last row of a matrix
///        contains the translation amounts.
/// \li Each of the Set() methods below completely rewrites the
///        matrix; for example, SetTranslate() yields a matrix
///        which does nothing but translate.
/// \li When multiplying two transformation matrices, the matrix
///        on the left applies a more local transformation to a row
///        vector. For example, if R represents a rotation
///        matrix and T represents a translation matrix, the
///        product R*T will rotate a row vector, then translate
///        it.
class GfMatrix4d
{
public:
    typedef double ScalarType;

    static const size_t numRows = 4;
    static const size_t numColumns = 4;

    /// Default constructor. Leaves the matrix component values undefined.
    GfMatrix4d() {}

    /// Constructor. Initializes the matrix from 16 independent
    /// \c double values, specified in row-major order. For example,
    /// parameter \e m10 specifies the value in row 1 and column 0.
    GfMatrix4d(double m00, double m01, double m02, double m03, 
               double m10, double m11, double m12, double m13, 
               double m20, double m21, double m22, double m23, 
               double m30, double m31, double m32, double m33) {
        Set(m00, m01, m02, m03, 
            m10, m11, m12, m13, 
            m20, m21, m22, m23, 
            m30, m31, m32, m33);
    }

    /// Constructor. Initializes the matrix from a 4x4 array
    /// of \c double values, specified in row-major order.
    GfMatrix4d(const double m[4][4]) {
        Set(m);
    }

    /// Constructor. Explicitly initializes the matrix to \e s times the
    /// identity matrix.
    explicit GfMatrix4d(double s) {
        SetDiagonal(s);
    }

    /// Constructor. Explicitly initializes the matrix to diagonal form,
    /// with the \e i th element on the diagonal set to <c>v[i]</c>.
    explicit GfMatrix4d(const GfVec4d& v) {
        SetDiagonal(v);
    }

    /// Constructor.  Initialize the matrix from a vector of vectors of
    /// double. The vector is expected to be 4x4. If it is
    /// too big, only the first 4 rows and/or columns will be used.
    /// If it is too small, uninitialized elements will be filled in with
    /// the corresponding elements from an identity matrix.
    ///
    explicit GfMatrix4d(const std::vector< std::vector<double> >& v);

    /// Constructor.  Initialize the matrix from a vector of vectors of
    /// float. The vector is expected to be 4x4. If it is
    /// too big, only the first 4 rows and/or columns will be used.
    /// If it is too small, uninitialized elements will be filled in with
    /// the corresponding elements from an identity matrix.
    ///
    explicit GfMatrix4d(const std::vector< std::vector<float> >& v);

    /// Constructor.  Initialize the matrix from 4 row vectors of
    /// double.  Each vector is expected to length 4.  If it is too
    /// big, only the first 4 items will be used.  If it is too small,
    /// uninitialized elements will be filled in with the
    /// corresponding elements from an identity matrix.
    ///
    explicit GfMatrix4d(const std::vector<double>& r0,
                        const std::vector<double>& r1,
                        const std::vector<double>& r2,
                        const std::vector<double>& r3);

    /// Constructor.  Initialize the matrix from 4 row vectors of
    /// float.  Each vector is expected to length 4.  If it is too
    /// big, only the first 4 items will be used.  If it is too small,
    /// uninitialized elements will be filled in with the
    /// corresponding elements from an identity matrix.
    ///
    explicit GfMatrix4d(const std::vector<float>& r0,
                        const std::vector<float>& r1,
                        const std::vector<float>& r2,
                        const std::vector<float>& r3);

    /// Constructor. Initializes a transformation matrix to perform the
    /// indicated rotation and translation.
    GfMatrix4d(const GfRotation& rotate,
               const GfVec3d& translate);

    /// Constructor. Initializes a transformation matrix to perform the
    /// indicated rotation and translation.
    GfMatrix4d(const GfMatrix3d& rotmx,
               const GfVec3d& translate);
    /// This explicit constructor converts a "float" matrix to a "double" matrix.
    explicit GfMatrix4d(const class GfMatrix4f& m);

    /// Sets a row of the matrix from a Vec4.
    void SetRow(int i, const GfVec4d & v) {
        _mtx[i][0] = v[0];
        _mtx[i][1] = v[1];
        _mtx[i][2] = v[2];
        _mtx[i][3] = v[3];
    }

    /// Sets a column of the matrix from a Vec4.
    void SetColumn(int i, const GfVec4d & v) {
        _mtx[0][i] = v[0];
        _mtx[1][i] = v[1];
        _mtx[2][i] = v[2];
        _mtx[3][i] = v[3];
    }

    /// Gets a row of the matrix as a Vec4.
    GfVec4d GetRow(int i) const {
        return GfVec4d(_mtx[i][0], _mtx[i][1], _mtx[i][2], _mtx[i][3]);
    }

    /// Gets a column of the matrix as a Vec4.
    GfVec4d GetColumn(int i) const {
        return GfVec4d(_mtx[0][i], _mtx[1][i], _mtx[2][i], _mtx[3][i]);
    }

    /// Sets the matrix from 16 independent \c double values,
    /// specified in row-major order. For example, parameter \e m10 specifies
    /// the value in row 1 and column 0.
    GfMatrix4d& Set(double m00, double m01, double m02, double m03, 
                    double m10, double m11, double m12, double m13, 
                    double m20, double m21, double m22, double m23, 
                    double m30, double m31, double m32, double m33) {
        _mtx[0][0] = m00; _mtx[0][1] = m01; _mtx[0][2] = m02; _mtx[0][3] = m03; 
        _mtx[1][0] = m10; _mtx[1][1] = m11; _mtx[1][2] = m12; _mtx[1][3] = m13; 
        _mtx[2][0] = m20; _mtx[2][1] = m21; _mtx[2][2] = m22; _mtx[2][3] = m23; 
        _mtx[3][0] = m30; _mtx[3][1] = m31; _mtx[3][2] = m32; _mtx[3][3] = m33;
        return *this;
    }

    /// Sets the matrix from a 4x4 array of \c double
    /// values, specified in row-major order.
    GfMatrix4d& Set(const double m[4][4]) {
        _mtx[0][0] = m[0][0];
        _mtx[0][1] = m[0][1];
        _mtx[0][2] = m[0][2];
        _mtx[0][3] = m[0][3];
        _mtx[1][0] = m[1][0];
        _mtx[1][1] = m[1][1];
        _mtx[1][2] = m[1][2];
        _mtx[1][3] = m[1][3];
        _mtx[2][0] = m[2][0];
        _mtx[2][1] = m[2][1];
        _mtx[2][2] = m[2][2];
        _mtx[2][3] = m[2][3];
        _mtx[3][0] = m[3][0];
        _mtx[3][1] = m[3][1];
        _mtx[3][2] = m[3][2];
        _mtx[3][3] = m[3][3];
        return *this;
    }

    /// Sets the matrix to the identity matrix.
    GfMatrix4d& SetIdentity() {
        return SetDiagonal(1);
    }

    /// Sets the matrix to zero.
    GfMatrix4d& SetZero() {
        return SetDiagonal(0);
    }

    /// Sets the matrix to \e s times the identity matrix.
    GfMatrix4d& SetDiagonal(double s);

    /// Sets the matrix to have diagonal (<c>v[0], v[1], v[2], v[3]</c>).
    GfMatrix4d& SetDiagonal(const GfVec4d&);

    /// Fills a 4x4 array of \c double values with the values in
    /// the matrix, specified in row-major order.
    double* Get(double m[4][4]);

    /// Returns vector components as an array of \c double values.
    double* GetArray()  {
        return _mtx.GetData();
    }

    /// Returns vector components as a const array of \c double values.
    const double* GetArray() const {
        return _mtx.GetData();
    }

    /// Accesses an indexed row \e i of the matrix as an array of 4 \c
    /// double values so that standard indexing (such as <c>m[0][1]</c>)
    /// works correctly.
    double* operator [](int i) { return _mtx[i]; }

    /// Accesses an indexed row \e i of the matrix as an array of 4 \c
    /// double values so that standard indexing (such as <c>m[0][1]</c>)
    /// works correctly.
    const double* operator [](int i) const { return _mtx[i]; }

    /// Hash.
    friend inline size_t hash_value(GfMatrix4d const &m) {
        int nElems = 4 * 4;
        size_t h = 0;
        const double *p = m.GetArray();
        while (nElems--)
            boost::hash_combine(h, *p++);
        return h;
    }

    /// Tests for element-wise matrix equality. All elements must match
    /// exactly for matrices to be considered equal.
    bool operator ==(const GfMatrix4d& m) const;

    /// Tests for element-wise matrix equality. All elements must match
    /// exactly for matrices to be considered equal.
    bool operator ==(const GfMatrix4f& m) const;

    /// Tests for element-wise matrix inequality. All elements must match
    /// exactly for matrices to be considered equal.
    bool operator !=(const GfMatrix4d& m) const {
        return !(*this == m);
    }

    /// Tests for element-wise matrix inequality. All elements must match
    /// exactly for matrices to be considered equal.
    bool operator !=(const GfMatrix4f& m) const {
        return !(*this == m);
    }

    /// Returns the transpose of the matrix.
    GfMatrix4d GetTranspose() const;

    /// Returns the inverse of the matrix, or FLT_MAX * SetIdentity() if the
    /// matrix is singular. (FLT_MAX is the largest value a \c float can have,
    /// as defined by the system.) The matrix is considered singular if the
    /// determinant is less than or equal to the optional parameter \e eps. If
    /// \e det is non-null, <c>*det</c> is set to the determinant.
    GfMatrix4d GetInverse(double* det = NULL, double eps = 0) const;

    /// Returns the determinant of the matrix.
    double GetDeterminant() const;

    /// Sets a row of the matrix from a Vec3.
    /// The fourth element of the row is ignored.
    void SetRow3(int i, const GfVec3d & v) {
        _mtx[i][0] = v[0];
        _mtx[i][1] = v[1];
        _mtx[i][2] = v[2];
    }

    /// Gets a row of the matrix as a Vec3.
    GfVec3d GetRow3(int i) const {
        return GfVec3d(_mtx[i][0], _mtx[i][1], _mtx[i][2]);
    }

    /// Returns the determinant of the upper 3x3 matrix. This method is useful
    /// when the matrix describes a linear transformation such as a rotation or
    /// scale because the other values in the 4x4 matrix are not important.
    double GetDeterminant3() const {
        return _GetDeterminant3(0, 1, 2, 0, 1, 2);
    }

    /// Returns true, if the row vectors of the upper 3x3 matrix form an
    /// orthogonal basis. Note they do not have to be unit length for this
    /// test to return true.
    bool HasOrthogonalRows3() const {
        // XXX Should add GfAreOrthogonal(v0, v1, v2) (which also
        //     GfRotation::Decompose() could use).
        GfVec3d axis0(GetRow3(0)), axis1(GetRow3(1)), axis2(GetRow3(2));
        return (GfAbs(GfDot(axis0, axis1)) < GF_MIN_ORTHO_TOLERANCE and
                GfAbs(GfDot(axis0, axis2)) < GF_MIN_ORTHO_TOLERANCE and
                GfAbs(GfDot(axis1, axis2)) < GF_MIN_ORTHO_TOLERANCE);
    }

    /// Makes the matrix orthonormal in place. This is an iterative method
    /// that is much more stable than the previous cross/cross method.  If the
    /// iterative method does not converge, a warning is issued.
    ///
    /// Returns true if the iteration converged, false otherwise.  Leaves any
    /// translation part of the matrix unchanged.  If \a issueWarning is true,
    /// this method will issue a warning if the iteration does not converge,
    /// otherwise it will be silent.
    bool Orthonormalize(bool issueWarning=true);

    /// Returns an orthonormalized copy of the matrix.
    GfMatrix4d GetOrthonormalized(bool issueWarning=true) const;

    /// Returns the sign of the determinant of the upper 3x3 matrix, i.e. 1
    /// for a right-handed matrix, -1 for a left-handed matrix, and 0 for a
    /// singular matrix.
    double GetHandedness() const;

    /// Returns true if the vectors in the upper 3x3 matrix form a
    /// right-handed coordinate system.
    bool IsRightHanded() const {
        return GetHandedness() == 1.0;
    }

    /// Returns true if the vectors in the upper 3x3 matrix form a left-handed
    /// coordinate system.
    bool IsLeftHanded() const {
        return GetHandedness() == -1.0;
    }

    /// Post-multiplies matrix \e m into this matrix.
    GfMatrix4d& operator *=(const GfMatrix4d& m);

    /// Multiplies the matrix by a double.
    GfMatrix4d& operator *=(double);

    /// Returns the product of a matrix and a double.
    friend GfMatrix4d operator *(const GfMatrix4d& m1, double d)
    {
        GfMatrix4d m = m1;
        return m *= d;
    }

    ///
    // Returns the product of a matrix and a double.
    friend GfMatrix4d operator *(double d, const GfMatrix4d& m)
    {
        return m * d;
    }

    /// Adds matrix \e m to this matrix.
    GfMatrix4d& operator +=(const GfMatrix4d& m);

    /// Subtracts matrix \e m from this matrix.
    GfMatrix4d& operator -=(const GfMatrix4d& m);

    /// Returns the unary negation of matrix \e m.
    friend GfMatrix4d operator -(const GfMatrix4d& m);

    /// Adds matrix \e m2 to \e m1
    friend GfMatrix4d operator +(const GfMatrix4d& m1, const GfMatrix4d& m2)
    {
        GfMatrix4d tmp(m1);
        tmp += m2;
        return tmp;
    }

    /// Subtracts matrix \e m2 from \e m1.
    friend GfMatrix4d operator -(const GfMatrix4d& m1, const GfMatrix4d& m2)
    {
        GfMatrix4d tmp(m1);
        tmp -= m2;
        return tmp;
    }

    /// Multiplies matrix \e m1 by \e m2.
    friend GfMatrix4d operator *(const GfMatrix4d& m1, const GfMatrix4d& m2)
    {
        GfMatrix4d tmp(m1);
        tmp *= m2;
        return tmp;
    }

    /// Divides matrix \e m1 by \e m2 (that is, <c>m1 * inv(m2)</c>).
    friend GfMatrix4d operator /(const GfMatrix4d& m1, const GfMatrix4d& m2)
    {
        return(m1 * m2.GetInverse());
    }

    /// Returns the product of a matrix \e m and a column vector \e vec.
    friend inline GfVec4d operator *(const GfMatrix4d& m, const GfVec4d& vec) {
        return GfVec4d(vec[0] * m._mtx[0][0] + vec[1] * m._mtx[0][1] + vec[2] * m._mtx[0][2] + vec[3] * m._mtx[0][3],
                       vec[0] * m._mtx[1][0] + vec[1] * m._mtx[1][1] + vec[2] * m._mtx[1][2] + vec[3] * m._mtx[1][3],
                       vec[0] * m._mtx[2][0] + vec[1] * m._mtx[2][1] + vec[2] * m._mtx[2][2] + vec[3] * m._mtx[2][3],
                       vec[0] * m._mtx[3][0] + vec[1] * m._mtx[3][1] + vec[2] * m._mtx[3][2] + vec[3] * m._mtx[3][3]);
    }

    /// Returns the product of row vector \e vec and a matrix \e m.
    friend inline GfVec4d operator *(const GfVec4d &vec, const GfMatrix4d& m) {
        return GfVec4d(vec[0] * m._mtx[0][0] + vec[1] * m._mtx[1][0] + vec[2] * m._mtx[2][0] + vec[3] * m._mtx[3][0],
                       vec[0] * m._mtx[0][1] + vec[1] * m._mtx[1][1] + vec[2] * m._mtx[2][1] + vec[3] * m._mtx[3][1],
                       vec[0] * m._mtx[0][2] + vec[1] * m._mtx[1][2] + vec[2] * m._mtx[2][2] + vec[3] * m._mtx[3][2],
                       vec[0] * m._mtx[0][3] + vec[1] * m._mtx[1][3] + vec[2] * m._mtx[2][3] + vec[3] * m._mtx[3][3]);
    }

    /// Returns the product of a matrix \e m and a column vector \e vec.
    /// Note that the return type is a \c GfVec4f.
    friend GfVec4f operator *(const GfMatrix4d& m, const GfVec4f& vec);

    /// Returns the product of row vector \e vec and a matrix \e m.
    /// Note that the return type is a \c GfVec4f.
    friend GfVec4f operator *(const GfVec4f &vec, const GfMatrix4d& m);

    /// Sets matrix to specify a uniform scaling by \e scaleFactor.
    GfMatrix4d& SetScale(double scaleFactor);

    /// Returns the matrix with any scaling or shearing removed,
    /// leaving only the rotation and translation.
    /// If the matrix cannot be decomposed, returns the original matrix.
    GfMatrix4d RemoveScaleShear() const;

    /// \name 3D Transformation Utilities
    /// @{

    /// Sets the matrix to specify a rotation equivalent to \e rot,
    /// and clears the translation.
    GfMatrix4d& SetRotate(const GfRotation &rot);

    /// Sets the matrix to specify a rotation equivalent to \e rot,
    /// without clearing the translation.
    GfMatrix4d& SetRotateOnly(const GfRotation &rot);

    /// Sets the matrix to specify a rotation equivalent to \e mx,
    /// and clears the translation.
    GfMatrix4d& SetRotate(const GfMatrix3d &mx);

    /// Sets the matrix to specify a rotation equivalent to \e mx,
    /// without clearing the translation.
    GfMatrix4d& SetRotateOnly(const GfMatrix3d &mx);

    /// Sets the matrix to specify a nonuniform scaling in x, y, and z by
    /// the factors in vector \e scaleFactors.
    GfMatrix4d& SetScale(const GfVec3d &scaleFactors);

    /// Sets matrix to specify a translation by the vector \e trans,
    /// and clears the rotation.
    GfMatrix4d& SetTranslate(const GfVec3d &trans);

    /// Sets matrix to specify a translation by the vector \e trans,
    /// without clearing the rotation.
    GfMatrix4d& SetTranslateOnly(const GfVec3d &t);

    /// Sets matrix to specify a rotation by \e rotate and a
    /// translation by \e translate.
    GfMatrix4d& SetTransform(const GfRotation& rotate,
                             const GfVec3d& translate);

    /// Sets matrix to specify a rotation by \e rotmx and a
    /// translation by \e translate.
    GfMatrix4d& SetTransform(const GfMatrix3d& rotmx,
                             const GfVec3d& translate);

    /// Sets the matrix to specify a viewing matrix from parameters
    /// similar to those used by <c>gluLookAt(3G)</c>. \e eyePoint
    /// represents the eye point in world space. \e centerPoint
    /// represents the world-space center of attention. \e upDirection
    /// is a vector indicating which way is up.
    GfMatrix4d& SetLookAt(const GfVec3d &eyePoint,
                          const GfVec3d &centerPoint,
                          const GfVec3d &upDirection);

    /// Sets the matrix to specify a viewing matrix from a world-space
    /// \e eyePoint and a world-space rotation that rigidly rotates the
    /// orientation from its canonical frame, which is defined to be
    /// looking along the <c>-z</c> axis with the <c>+y</c> axis as the up
    /// direction.
    GfMatrix4d& SetLookAt(const GfVec3d &eyePoint,
                          const GfRotation &orientation);

    /// Factors the matrix into 5 components:
    /// \li <c>\e M = r * s * -r * u * t</c>
    /// where
    /// \li \e t is a translation.
    /// \li \e u and \e r are rotations, and \e -r is the transpose
    ///     (inverse) of \e r. The \e u matrix may contain shear
    ///     information.
    /// \li \e s is a scale.
    /// Any projection information could be returned in matrix \e p,
    /// but currently p is never modified.
    ///
    /// Returns \c false if the matrix is singular (as determined by \e eps).
    /// In that case, any zero scales in \e s are clamped to \e eps
    /// to allow computation of \e u.
    bool Factor(GfMatrix4d* r, GfVec3d* s, GfMatrix4d* u,
                GfVec3d* t, GfMatrix4d* p,
                double eps = GF_MIN_VECTOR_LENGTH) const;

    /// Returns the translation part of the matrix, defined as the first three
    /// elements of the last row.
    GfVec3d ExtractTranslation() const {
        return GfVec3d(_mtx[3][0], _mtx[3][1], _mtx[3][2]);
    }

    /// Returns the rotation corresponding to this matrix. This works well
    /// only if the matrix represents a rotation.
    ///
    /// For good results, consider calling Orthonormalize() before calling
    /// this method.
    GfRotation ExtractRotation() const;

    /// Decompose the rotation corresponding to this matrix about 3 orthogonal
    /// axes.  If the axes are not orthogonal, warnings will be spewed.
    ///
    /// This is a convenience method that is equivalent to calling
    /// ExtractRotation().Decompose().
    GfVec3d DecomposeRotation(const GfVec3d &axis0,
                              const GfVec3d &axis1,
                              const GfVec3d &axis2) const;

    /// Returns the rotation corresponding to this matrix. This works well
    /// only if the matrix represents a rotation.
    ///
    /// For good results, consider calling Orthonormalize() before calling
    /// this method.
    GfMatrix3d ExtractRotationMatrix() const;

    /// Transforms the row vector \e vec by the matrix, returning the result.
    /// This treats the vector as a 4-component vector whose fourth component
    /// is 1.
    GfVec3d Transform(const GfVec3d &vec) const {
        return GfProject(GfVec4d(
            vec[0] * _mtx[0][0] + vec[1] * _mtx[1][0] + vec[2] * _mtx[2][0] + _mtx[3][0],
            vec[0] * _mtx[0][1] + vec[1] * _mtx[1][1] + vec[2] * _mtx[2][1] + _mtx[3][1],
            vec[0] * _mtx[0][2] + vec[1] * _mtx[1][2] + vec[2] * _mtx[2][2] + _mtx[3][2],
            vec[0] * _mtx[0][3] + vec[1] * _mtx[1][3] + vec[2] * _mtx[2][3] + _mtx[3][3]));
    }

    /// Transforms the row vector \e vec by the matrix, returning the result.
    /// This treats the vector as a 4-component vector whose fourth component
    /// is 1. This is an overloaded method; it differs from the other version
    /// in that it returns a different value type.
    GfVec3f Transform(const GfVec3f &vec) const {
        return GfVec3f(GfProject(GfVec4d(
            vec[0] * _mtx[0][0] + vec[1] * _mtx[1][0] + vec[2] * _mtx[2][0] + _mtx[3][0],
            vec[0] * _mtx[0][1] + vec[1] * _mtx[1][1] + vec[2] * _mtx[2][1] + _mtx[3][1],
            vec[0] * _mtx[0][2] + vec[1] * _mtx[1][2] + vec[2] * _mtx[2][2] + _mtx[3][2],
            vec[0] * _mtx[0][3] + vec[1] * _mtx[1][3] + vec[2] * _mtx[2][3] + _mtx[3][3])));
    }

    /// Transforms row vector \e vec by the matrix, returning the result. This
    /// treats the vector as a direction vector, so the translation
    /// information in the matrix is ignored. That is, it treats the vector as
    /// a 4-component vector whose fourth component is 0.
    GfVec3d TransformDir(const GfVec3d &vec) const {
        return GfVec3d(
            vec[0] * _mtx[0][0] + vec[1] * _mtx[1][0] + vec[2] * _mtx[2][0],
            vec[0] * _mtx[0][1] + vec[1] * _mtx[1][1] + vec[2] * _mtx[2][1],
            vec[0] * _mtx[0][2] + vec[1] * _mtx[1][2] + vec[2] * _mtx[2][2]);
    }

    /// Transforms row vector \e vec by the matrix, returning the result. This
    /// treats the vector as a direction vector, so the translation
    /// information in the matrix is ignored. That is, it treats the vector as
    /// a 4-component vector whose fourth component is 0.  This is an
    /// overloaded method; it differs from the other version in that it
    /// returns a different value type.
    GfVec3f TransformDir(const GfVec3f &vec) const {
        return GfVec3f(
            vec[0] * _mtx[0][0] + vec[1] * _mtx[1][0] + vec[2] * _mtx[2][0],
            vec[0] * _mtx[0][1] + vec[1] * _mtx[1][1] + vec[2] * _mtx[2][1],
            vec[0] * _mtx[0][2] + vec[1] * _mtx[1][2] + vec[2] * _mtx[2][2]);
    }

    /// Transforms the row vector \e vec by the matrix, returning the result.
    /// This treats the vector as a 4-component vector whose fourth component
    /// is 1 and ignores the fourth column of the matrix (i.e. assumes it is
    /// (0, 0, 0, 1)).
    GfVec3d TransformAffine(const GfVec3d &vec) const {
        return GfVec3d(
            vec[0] * _mtx[0][0] + vec[1] * _mtx[1][0] + vec[2] * _mtx[2][0] + _mtx[3][0],
            vec[0] * _mtx[0][1] + vec[1] * _mtx[1][1] + vec[2] * _mtx[2][1] + _mtx[3][1],
            vec[0] * _mtx[0][2] + vec[1] * _mtx[1][2] + vec[2] * _mtx[2][2] + _mtx[3][2]);
    }

    /// Transforms the row vector \e vec by the matrix, returning the result.
    /// This treats the vector as a 4-component vector whose fourth component
    /// is 1 and ignores the fourth column of the matrix (i.e. assumes it is
    /// (0, 0, 0, 1)).
    GfVec3f TransformAffine(const GfVec3f &vec) const {
        return GfVec3f(
            vec[0] * _mtx[0][0] + vec[1] * _mtx[1][0] + vec[2] * _mtx[2][0] + _mtx[3][0],
            vec[0] * _mtx[0][1] + vec[1] * _mtx[1][1] + vec[2] * _mtx[2][1] + _mtx[3][1],
            vec[0] * _mtx[0][2] + vec[1] * _mtx[1][2] + vec[2] * _mtx[2][2] + _mtx[3][2]);
    }
    /// @}

private:
    /// Returns the determinant of the 3x3 submatrix specified by the three
    /// given row and column indices (0-3 for each).
    double _GetDeterminant3(size_t row1, size_t row2, size_t row3,
       size_t col1, size_t col2, size_t col3) const;

    /// Diagonalizes the upper 3x3 matrix of a matrix known to be symmetric.
    void _Jacobi3(GfVec3d *eigenvalues, GfVec3d eigenvectors[3]) const;

private:
    /// Matrix storage, in row-major order.
    GfMatrixData<double, 4, 4> _mtx;

    // Friend declarations
    friend class GfMatrix4f;
};

/// Output a GfMatrix4d
/// \ingroup group_gf_DebuggingOutput
std::ostream& operator<<(std::ostream &, GfMatrix4d const &);

#endif // GF_MATRIX4D_H