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Diffstat (limited to 'eigen/Eigen/src/Geometry/Hyperplane.h')
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diff --git a/eigen/Eigen/src/Geometry/Hyperplane.h b/eigen/Eigen/src/Geometry/Hyperplane.h new file mode 100644 index 0000000..00b7c43 --- /dev/null +++ b/eigen/Eigen/src/Geometry/Hyperplane.h @@ -0,0 +1,280 @@ +// This file is part of Eigen, a lightweight C++ template library +// for linear algebra. +// +// Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr> +// Copyright (C) 2008 Benoit Jacob <jacob.benoit.1@gmail.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/. + +#ifndef EIGEN_HYPERPLANE_H +#define EIGEN_HYPERPLANE_H + +namespace Eigen { + +/** \geometry_module \ingroup Geometry_Module + * + * \class Hyperplane + * + * \brief A hyperplane + * + * A hyperplane is an affine subspace of dimension n-1 in a space of dimension n. + * For example, a hyperplane in a plane is a line; a hyperplane in 3-space is a plane. + * + * \param _Scalar the scalar type, i.e., the type of the coefficients + * \param _AmbientDim the dimension of the ambient space, can be a compile time value or Dynamic. + * Notice that the dimension of the hyperplane is _AmbientDim-1. + * + * This class represents an hyperplane as the zero set of the implicit equation + * \f$ n \cdot x + d = 0 \f$ where \f$ n \f$ is a unit normal vector of the plane (linear part) + * and \f$ d \f$ is the distance (offset) to the origin. + */ +template <typename _Scalar, int _AmbientDim, int _Options> +class Hyperplane +{ +public: + EIGEN_MAKE_ALIGNED_OPERATOR_NEW_IF_VECTORIZABLE_FIXED_SIZE(_Scalar,_AmbientDim==Dynamic ? Dynamic : _AmbientDim+1) + enum { + AmbientDimAtCompileTime = _AmbientDim, + Options = _Options + }; + typedef _Scalar Scalar; + typedef typename NumTraits<Scalar>::Real RealScalar; + typedef DenseIndex Index; + typedef Matrix<Scalar,AmbientDimAtCompileTime,1> VectorType; + typedef Matrix<Scalar,Index(AmbientDimAtCompileTime)==Dynamic + ? Dynamic + : Index(AmbientDimAtCompileTime)+1,1,Options> Coefficients; + typedef Block<Coefficients,AmbientDimAtCompileTime,1> NormalReturnType; + typedef const Block<const Coefficients,AmbientDimAtCompileTime,1> ConstNormalReturnType; + + /** Default constructor without initialization */ + inline Hyperplane() {} + + template<int OtherOptions> + Hyperplane(const Hyperplane<Scalar,AmbientDimAtCompileTime,OtherOptions>& other) + : m_coeffs(other.coeffs()) + {} + + /** Constructs a dynamic-size hyperplane with \a _dim the dimension + * of the ambient space */ + inline explicit Hyperplane(Index _dim) : m_coeffs(_dim+1) {} + + /** Construct a plane from its normal \a n and a point \a e onto the plane. + * \warning the vector normal is assumed to be normalized. + */ + inline Hyperplane(const VectorType& n, const VectorType& e) + : m_coeffs(n.size()+1) + { + normal() = n; + offset() = -n.dot(e); + } + + /** Constructs a plane from its normal \a n and distance to the origin \a d + * such that the algebraic equation of the plane is \f$ n \cdot x + d = 0 \f$. + * \warning the vector normal is assumed to be normalized. + */ + inline Hyperplane(const VectorType& n, const Scalar& d) + : m_coeffs(n.size()+1) + { + normal() = n; + offset() = d; + } + + /** Constructs a hyperplane passing through the two points. If the dimension of the ambient space + * is greater than 2, then there isn't uniqueness, so an arbitrary choice is made. + */ + static inline Hyperplane Through(const VectorType& p0, const VectorType& p1) + { + Hyperplane result(p0.size()); + result.normal() = (p1 - p0).unitOrthogonal(); + result.offset() = -p0.dot(result.normal()); + return result; + } + + /** Constructs a hyperplane passing through the three points. The dimension of the ambient space + * is required to be exactly 3. + */ + static inline Hyperplane Through(const VectorType& p0, const VectorType& p1, const VectorType& p2) + { + EIGEN_STATIC_ASSERT_VECTOR_SPECIFIC_SIZE(VectorType, 3) + Hyperplane result(p0.size()); + VectorType v0(p2 - p0), v1(p1 - p0); + result.normal() = v0.cross(v1); + RealScalar norm = result.normal().norm(); + if(norm <= v0.norm() * v1.norm() * NumTraits<RealScalar>::epsilon()) + { + Matrix<Scalar,2,3> m; m << v0.transpose(), v1.transpose(); + JacobiSVD<Matrix<Scalar,2,3> > svd(m, ComputeFullV); + result.normal() = svd.matrixV().col(2); + } + else + result.normal() /= norm; + result.offset() = -p0.dot(result.normal()); + return result; + } + + /** Constructs a hyperplane passing through the parametrized line \a parametrized. + * If the dimension of the ambient space is greater than 2, then there isn't uniqueness, + * so an arbitrary choice is made. + */ + // FIXME to be consitent with the rest this could be implemented as a static Through function ?? + explicit Hyperplane(const ParametrizedLine<Scalar, AmbientDimAtCompileTime>& parametrized) + { + normal() = parametrized.direction().unitOrthogonal(); + offset() = -parametrized.origin().dot(normal()); + } + + ~Hyperplane() {} + + /** \returns the dimension in which the plane holds */ + inline Index dim() const { return AmbientDimAtCompileTime==Dynamic ? m_coeffs.size()-1 : Index(AmbientDimAtCompileTime); } + + /** normalizes \c *this */ + void normalize(void) + { + m_coeffs /= normal().norm(); + } + + /** \returns the signed distance between the plane \c *this and a point \a p. + * \sa absDistance() + */ + inline Scalar signedDistance(const VectorType& p) const { return normal().dot(p) + offset(); } + + /** \returns the absolute distance between the plane \c *this and a point \a p. + * \sa signedDistance() + */ + inline Scalar absDistance(const VectorType& p) const { using std::abs; return abs(signedDistance(p)); } + + /** \returns the projection of a point \a p onto the plane \c *this. + */ + inline VectorType projection(const VectorType& p) const { return p - signedDistance(p) * normal(); } + + /** \returns a constant reference to the unit normal vector of the plane, which corresponds + * to the linear part of the implicit equation. + */ + inline ConstNormalReturnType normal() const { return ConstNormalReturnType(m_coeffs,0,0,dim(),1); } + + /** \returns a non-constant reference to the unit normal vector of the plane, which corresponds + * to the linear part of the implicit equation. + */ + inline NormalReturnType normal() { return NormalReturnType(m_coeffs,0,0,dim(),1); } + + /** \returns the distance to the origin, which is also the "constant term" of the implicit equation + * \warning the vector normal is assumed to be normalized. + */ + inline const Scalar& offset() const { return m_coeffs.coeff(dim()); } + + /** \returns a non-constant reference to the distance to the origin, which is also the constant part + * of the implicit equation */ + inline Scalar& offset() { return m_coeffs(dim()); } + + /** \returns a constant reference to the coefficients c_i of the plane equation: + * \f$ c_0*x_0 + ... + c_{d-1}*x_{d-1} + c_d = 0 \f$ + */ + inline const Coefficients& coeffs() const { return m_coeffs; } + + /** \returns a non-constant reference to the coefficients c_i of the plane equation: + * \f$ c_0*x_0 + ... + c_{d-1}*x_{d-1} + c_d = 0 \f$ + */ + inline Coefficients& coeffs() { return m_coeffs; } + + /** \returns the intersection of *this with \a other. + * + * \warning The ambient space must be a plane, i.e. have dimension 2, so that \c *this and \a other are lines. + * + * \note If \a other is approximately parallel to *this, this method will return any point on *this. + */ + VectorType intersection(const Hyperplane& other) const + { + using std::abs; + EIGEN_STATIC_ASSERT_VECTOR_SPECIFIC_SIZE(VectorType, 2) + Scalar det = coeffs().coeff(0) * other.coeffs().coeff(1) - coeffs().coeff(1) * other.coeffs().coeff(0); + // since the line equations ax+by=c are normalized with a^2+b^2=1, the following tests + // whether the two lines are approximately parallel. + if(internal::isMuchSmallerThan(det, Scalar(1))) + { // special case where the two lines are approximately parallel. Pick any point on the first line. + if(abs(coeffs().coeff(1))>abs(coeffs().coeff(0))) + return VectorType(coeffs().coeff(1), -coeffs().coeff(2)/coeffs().coeff(1)-coeffs().coeff(0)); + else + return VectorType(-coeffs().coeff(2)/coeffs().coeff(0)-coeffs().coeff(1), coeffs().coeff(0)); + } + else + { // general case + Scalar invdet = Scalar(1) / det; + return VectorType(invdet*(coeffs().coeff(1)*other.coeffs().coeff(2)-other.coeffs().coeff(1)*coeffs().coeff(2)), + invdet*(other.coeffs().coeff(0)*coeffs().coeff(2)-coeffs().coeff(0)*other.coeffs().coeff(2))); + } + } + + /** Applies the transformation matrix \a mat to \c *this and returns a reference to \c *this. + * + * \param mat the Dim x Dim transformation matrix + * \param traits specifies whether the matrix \a mat represents an #Isometry + * or a more generic #Affine transformation. The default is #Affine. + */ + template<typename XprType> + inline Hyperplane& transform(const MatrixBase<XprType>& mat, TransformTraits traits = Affine) + { + if (traits==Affine) + normal() = mat.inverse().transpose() * normal(); + else if (traits==Isometry) + normal() = mat * normal(); + else + { + eigen_assert(0 && "invalid traits value in Hyperplane::transform()"); + } + return *this; + } + + /** Applies the transformation \a t to \c *this and returns a reference to \c *this. + * + * \param t the transformation of dimension Dim + * \param traits specifies whether the transformation \a t represents an #Isometry + * or a more generic #Affine transformation. The default is #Affine. + * Other kind of transformations are not supported. + */ + template<int TrOptions> + inline Hyperplane& transform(const Transform<Scalar,AmbientDimAtCompileTime,Affine,TrOptions>& t, + TransformTraits traits = Affine) + { + transform(t.linear(), traits); + offset() -= normal().dot(t.translation()); + return *this; + } + + /** \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<Hyperplane, + Hyperplane<NewScalarType,AmbientDimAtCompileTime,Options> >::type cast() const + { + return typename internal::cast_return_type<Hyperplane, + Hyperplane<NewScalarType,AmbientDimAtCompileTime,Options> >::type(*this); + } + + /** Copy constructor with scalar type conversion */ + template<typename OtherScalarType,int OtherOptions> + inline explicit Hyperplane(const Hyperplane<OtherScalarType,AmbientDimAtCompileTime,OtherOptions>& other) + { m_coeffs = other.coeffs().template cast<Scalar>(); } + + /** \returns \c true if \c *this is approximately equal to \a other, within the precision + * determined by \a prec. + * + * \sa MatrixBase::isApprox() */ + template<int OtherOptions> + bool isApprox(const Hyperplane<Scalar,AmbientDimAtCompileTime,OtherOptions>& other, const typename NumTraits<Scalar>::Real& prec = NumTraits<Scalar>::dummy_precision()) const + { return m_coeffs.isApprox(other.m_coeffs, prec); } + +protected: + + Coefficients m_coeffs; +}; + +} // end namespace Eigen + +#endif // EIGEN_HYPERPLANE_H |