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AngleAxis.h
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// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef EIGEN_ANGLEAXIS_H
#define EIGEN_ANGLEAXIS_H
namespace Eigen {
/** \geometry_module \ingroup Geometry_Module
*
* \class AngleAxis
*
* \brief Represents a 3D rotation as a rotation angle around an arbitrary 3D axis
*
* \param _Scalar the scalar type, i.e., the type of the coefficients.
*
* \warning When setting up an AngleAxis object, the axis vector \b must \b be \b normalized.
*
* The following two typedefs are provided for convenience:
* \li \c AngleAxisf for \c float
* \li \c AngleAxisd for \c double
*
* Combined with MatrixBase::Unit{X,Y,Z}, AngleAxis can be used to easily
* mimic Euler-angles. Here is an example:
* \include AngleAxis_mimic_euler.cpp
* Output: \verbinclude AngleAxis_mimic_euler.out
*
* \note This class is not aimed to be used to store a rotation transformation,
* but rather to make easier the creation of other rotation (Quaternion, rotation Matrix)
* and transformation objects.
*
* \sa class Quaternion, class Transform, MatrixBase::UnitX()
*/
namespace internal {
template<typename _Scalar> struct traits<AngleAxis<_Scalar> >
{
typedef _Scalar Scalar;
};
}
template<typename _Scalar>
class AngleAxis : public RotationBase<AngleAxis<_Scalar>,3>
{
typedef RotationBase<AngleAxis<_Scalar>,3> Base;
public:
using Base::operator*;
enum { Dim = 3 };
/** the scalar type of the coefficients */
typedef _Scalar Scalar;
typedef Matrix<Scalar,3,3> Matrix3;
typedef Matrix<Scalar,3,1> Vector3;
typedef Quaternion<Scalar> QuaternionType;
protected:
Vector3 m_axis;
Scalar m_angle;
public:
/** Default constructor without initialization. */
AngleAxis() {}
/** Constructs and initialize the angle-axis rotation from an \a angle in radian
* and an \a axis which \b must \b be \b normalized.
*
* \warning If the \a axis vector is not normalized, then the angle-axis object
* represents an invalid rotation. */
template<typename Derived>
inline AngleAxis(const Scalar& angle, const MatrixBase<Derived>& axis) : m_axis(axis), m_angle(angle) {}
/** Constructs and initialize the angle-axis rotation from a quaternion \a q. */
template<typename QuatDerived> inline explicit AngleAxis(const QuaternionBase<QuatDerived>& q) { *this = q; }
/** Constructs and initialize the angle-axis rotation from a 3x3 rotation matrix. */
template<typename Derived>
inline explicit AngleAxis(const MatrixBase<Derived>& m) { *this = m; }
/** \returns the value of the rotation angle in radian */
Scalar angle() const { return m_angle; }
/** \returns a read-write reference to the stored angle in radian */
Scalar& angle() { return m_angle; }
/** \returns the rotation axis */
const Vector3& axis() const { return m_axis; }
/** \returns a read-write reference to the stored rotation axis.
*
* \warning The rotation axis must remain a \b unit vector.
*/
Vector3& axis() { return m_axis; }
/** Concatenates two rotations */
inline QuaternionType operator* (const AngleAxis& other) const
{ return QuaternionType(*this) * QuaternionType(other); }
/** Concatenates two rotations */
inline QuaternionType operator* (const QuaternionType& other) const
{ return QuaternionType(*this) * other; }
/** Concatenates two rotations */
friend inline QuaternionType operator* (const QuaternionType& a, const AngleAxis& b)
{ return a * QuaternionType(b); }
/** \returns the inverse rotation, i.e., an angle-axis with opposite rotation angle */
AngleAxis inverse() const
{ return AngleAxis(-m_angle, m_axis); }
template<class QuatDerived>
AngleAxis& operator=(const QuaternionBase<QuatDerived>& q);
template<typename Derived>
AngleAxis& operator=(const MatrixBase<Derived>& m);
template<typename Derived>
AngleAxis& fromRotationMatrix(const MatrixBase<Derived>& m);
Matrix3 toRotationMatrix(void) const;
/** \returns \c *this with scalar type casted to \a NewScalarType
*
* Note that if \a NewScalarType is equal to the current scalar type of \c *this
* then this function smartly returns a const reference to \c *this.
*/
template<typename NewScalarType>
inline typename internal::cast_return_type<AngleAxis,AngleAxis<NewScalarType> >::type cast() const
{ return typename internal::cast_return_type<AngleAxis,AngleAxis<NewScalarType> >::type(*this); }
/** Copy constructor with scalar type conversion */
template<typename OtherScalarType>
inline explicit AngleAxis(const AngleAxis<OtherScalarType>& other)
{
m_axis = other.axis().template cast<Scalar>();
m_angle = Scalar(other.angle());
}
static inline const AngleAxis Identity() { return AngleAxis(Scalar(0), Vector3::UnitX()); }
/** \returns \c true if \c *this is approximately equal to \a other, within the precision
* determined by \a prec.
*
* \sa MatrixBase::isApprox() */
bool isApprox(const AngleAxis& other, const typename NumTraits<Scalar>::Real& prec = NumTraits<Scalar>::dummy_precision()) const
{ return m_axis.isApprox(other.m_axis, prec) && internal::isApprox(m_angle,other.m_angle, prec); }
};
/** \ingroup Geometry_Module
* single precision angle-axis type */
typedef AngleAxis<float> AngleAxisf;
/** \ingroup Geometry_Module
* double precision angle-axis type */
typedef AngleAxis<double> AngleAxisd;
/** Set \c *this from a \b unit quaternion.
* The axis is normalized.
*
* \warning As any other method dealing with quaternion, if the input quaternion
* is not normalized then the result is undefined.
*/
template<typename Scalar>
template<typename QuatDerived>
AngleAxis<Scalar>& AngleAxis<Scalar>::operator=(const QuaternionBase<QuatDerived>& q)
{
using std::acos;
using std::min;
using std::max;
using std::sqrt;
Scalar n2 = q.vec().squaredNorm();
if (n2 < NumTraits<Scalar>::dummy_precision()*NumTraits<Scalar>::dummy_precision())
{
m_angle = Scalar(0);
m_axis << Scalar(1), Scalar(0), Scalar(0);
}
else
{
m_angle = Scalar(2)*acos((min)((max)(Scalar(-1),q.w()),Scalar(1)));
m_axis = q.vec() / sqrt(n2);
}
return *this;
}
/** Set \c *this from a 3x3 rotation matrix \a mat.
*/
template<typename Scalar>
template<typename Derived>
AngleAxis<Scalar>& AngleAxis<Scalar>::operator=(const MatrixBase<Derived>& mat)
{
// Since a direct conversion would not be really faster,
// let's use the robust Quaternion implementation:
return *this = QuaternionType(mat);
}
/**
* \brief Sets \c *this from a 3x3 rotation matrix.
**/
template<typename Scalar>
template<typename Derived>
AngleAxis<Scalar>& AngleAxis<Scalar>::fromRotationMatrix(const MatrixBase<Derived>& mat)
{
return *this = QuaternionType(mat);
}
/** Constructs and \returns an equivalent 3x3 rotation matrix.
*/
template<typename Scalar>
typename AngleAxis<Scalar>::Matrix3
AngleAxis<Scalar>::toRotationMatrix(void) const
{
using std::sin;
using std::cos;
Matrix3 res;
Vector3 sin_axis = sin(m_angle) * m_axis;
Scalar c = cos(m_angle);
Vector3 cos1_axis = (Scalar(1)-c) * m_axis;
Scalar tmp;
tmp = cos1_axis.x() * m_axis.y();
res.coeffRef(0,1) = tmp - sin_axis.z();
res.coeffRef(1,0) = tmp + sin_axis.z();
tmp = cos1_axis.x() * m_axis.z();
res.coeffRef(0,2) = tmp + sin_axis.y();
res.coeffRef(2,0) = tmp - sin_axis.y();
tmp = cos1_axis.y() * m_axis.z();
res.coeffRef(1,2) = tmp - sin_axis.x();
res.coeffRef(2,1) = tmp + sin_axis.x();
res.diagonal() = (cos1_axis.cwiseProduct(m_axis)).array() + c;
return res;
}
} // end namespace Eigen
#endif // EIGEN_ANGLEAXIS_H

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