// This file is part of Eigen, a lightweight C++ template library // for linear algebra. // // Copyright (C) 2015 Tal Hadad <tal_hd@hotmail.com> // // 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/.
/** \brief Representation of a fixed signed rotation axis for EulerSystem. * * \ingroup EulerAngles_Module * * Values here represent: * - The axis of the rotation: X, Y or Z. * - The sign (i.e. direction of the rotation along the axis): positive(+) or negative(-) * * Therefore, this could express all the axes {+X,+Y,+Z,-X,-Y,-Z} * * For positive axis, use +EULER_{axis}, and for negative axis use -EULER_{axis}.
*/ enum EulerAxis
{
EULER_X = 1, /*!< the X axis */
EULER_Y = 2, /*!< the Y axis */
EULER_Z = 3 /*!< the Z axis */
};
/** \class EulerSystem * * \ingroup EulerAngles_Module * * \brief Represents a fixed Euler rotation system. * * This meta-class goal is to represent the Euler system in compilation time, for EulerAngles. * * You can use this class to get two things: * - Build an Euler system, and then pass it as a template parameter to EulerAngles. * - Query some compile time data about an Euler system. (e.g. Whether it's Tait-Bryan) * * Euler rotation is a set of three rotation on fixed axes. (see \ref EulerAngles) * This meta-class store constantly those signed axes. (see \ref EulerAxis) * * ### Types of Euler systems ### * * All and only valid 3 dimension Euler rotation over standard * signed axes{+X,+Y,+Z,-X,-Y,-Z} are supported: * - all axes X, Y, Z in each valid order (see below what order is valid) * - rotation over the axis is supported both over the positive and negative directions. * - both Tait-Bryan and proper/classic Euler angles (i.e. the opposite). * * Since EulerSystem support both positive and negative directions, * you may call this rotation distinction in other names: * - _right handed_ or _left handed_ * - _counterclockwise_ or _clockwise_ * * Notice all axed combination are valid, and would trigger a static assertion. * Same unsigned axes can't be neighbors, e.g. {X,X,Y} is invalid. * This yield two and only two classes: * - _Tait-Bryan_ - all unsigned axes are distinct, e.g. {X,Y,Z} * - _proper/classic Euler angles_ - The first and the third unsigned axes is equal, * and the second is different, e.g. {X,Y,X} * * ### Intrinsic vs extrinsic Euler systems ### * * Only intrinsic Euler systems are supported for simplicity. * If you want to use extrinsic Euler systems, * just use the equal intrinsic opposite order for axes and angles. * I.e axes (A,B,C) becomes (C,B,A), and angles (a,b,c) becomes (c,b,a). * * ### Convenient user typedefs ### * * Convenient typedefs for EulerSystem exist (only for positive axes Euler systems), * in a form of EulerSystem{A}{B}{C}, e.g. \ref EulerSystemXYZ. * * ### Additional reading ### * * More information about Euler angles: https://en.wikipedia.org/wiki/Euler_angles * * \tparam _AlphaAxis the first fixed EulerAxis * * \tparam _BetaAxis the second fixed EulerAxis * * \tparam _GammaAxis the third fixed EulerAxis
*/ template <int _AlphaAxis, int _BetaAxis, int _GammaAxis> class EulerSystem
{ public: // It's defined this way and not as enum, because I think // that enum is not guerantee to support negative numbers
/** The first rotation axis */ staticconstint AlphaAxis = _AlphaAxis;
/** The second rotation axis */ staticconstint BetaAxis = _BetaAxis;
/** The third rotation axis */ staticconstint GammaAxis = _GammaAxis;
enum
{
AlphaAxisAbs = internal::Abs<AlphaAxis>::value, /*!< the first rotation axis unsigned */
BetaAxisAbs = internal::Abs<BetaAxis>::value, /*!< the second rotation axis unsigned */
GammaAxisAbs = internal::Abs<GammaAxis>::value, /*!< the third rotation axis unsigned */
// Parity is even if alpha axis X is followed by beta axis Y, or Y is followed // by Z, or Z is followed by X; otherwise it is odd.
IsOdd = ((AlphaAxisAbs)%3 == (BetaAxisAbs - 1)%3) ? 0 : 1, /*!< whether the Euler system is odd */
IsEven = IsOdd ? 0 : 1, /*!< whether the Euler system is even */
IsTaitBryan = ((unsigned)AlphaAxisAbs != (unsigned)GammaAxisAbs) ? 1 : 0 /*!< whether the Euler system is Tait-Bryan */
};
staticconstint // I, J, K are the pivot indexes permutation for the rotation matrix, that match this Euler system. // They are used in this class converters. // They are always different from each other, and their possible values are: 0, 1, or 2.
I_ = AlphaAxisAbs - 1,
J_ = (AlphaAxisAbs - 1 + 1 + IsOdd)%3,
K_ = (AlphaAxisAbs - 1 + 2 - IsOdd)%3
;
// TODO: Get @mat parameter in form that avoids double evaluation. template <typename Derived> staticvoid CalcEulerAngles_imp(Matrix<typename MatrixBase<Derived>::Scalar, 3, 1>& res, const MatrixBase<Derived>& mat, internal::true_type /*isTaitBryan*/)
{ using std::atan2; using std::sqrt;
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