Scaling.h

// 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/.
// SPDX-License-Identifier: MPL-2.0
 
#ifndef EIGEN_SCALING_H
#define EIGEN_SCALING_H
 
// IWYU pragma: private
#include "./InternalHeaderCheck.h"
 
namespace Eigen {

 
namespace internal {
// This helper helps nvcc+MSVC to properly parse this file.
// See bug 1412.
template <typename Scalar, int Dim, int Mode>
struct uniformscaling_times_affine_returntype {
  enum { NewMode = int(Mode) == int(Isometry) ? Affine : Mode };
  using type = Transform<Scalar, Dim, NewMode>;
};
}  // namespace internal
 
template <typename Scalar_>
class UniformScaling {
 public:
  using Scalar = Scalar_;
 
 protected:
  Scalar m_factor;
 
 public:
  UniformScaling() {}
  explicit inline UniformScaling(const Scalar& s) : m_factor(s) {}
 
  inline const Scalar& factor() const { return m_factor; }
  inline Scalar& factor() { return m_factor; }

  inline UniformScaling operator*(const UniformScaling& other) const {
    return UniformScaling(m_factor * other.factor());
  }

  template <int Dim>
  inline Transform<Scalar, Dim, Affine> operator*(const Translation<Scalar, Dim>& t) const;

  template <int Dim, int Mode, int Options>
  inline typename internal::uniformscaling_times_affine_returntype<Scalar, Dim, Mode>::type operator*(
      const Transform<Scalar, Dim, Mode, Options>& t) const {
    typename internal::uniformscaling_times_affine_returntype<Scalar, Dim, Mode>::type res = t;
    res.prescale(factor());
    return res;
  }

  // TODO: return an expression instead of a dense matrix.
  template <typename Derived>
  inline typename Eigen::internal::plain_matrix_type<Derived>::type operator*(const MatrixBase<Derived>& other) const {
    return other * m_factor;
  }
 
  template <typename Derived, int Dim>
  inline Matrix<Scalar, Dim, Dim> operator*(const RotationBase<Derived, Dim>& r) const {
    return r.toRotationMatrix() * m_factor;
  }

  inline UniformScaling inverse() const { return UniformScaling(Scalar(1) / m_factor); }

  template <typename NewScalarType>
  inline UniformScaling<NewScalarType> cast() const {
    return UniformScaling<NewScalarType>(NewScalarType(m_factor));
  }

  template <typename OtherScalarType>
  inline explicit UniformScaling(const UniformScaling<OtherScalarType>& other) {
    m_factor = Scalar(other.factor());
  }

  bool isApprox(const UniformScaling& other,
                const typename NumTraits<Scalar>::Real& prec = NumTraits<Scalar>::dummy_precision()) const {
    return internal::isApprox(m_factor, other.factor(), prec);
  }
};


// NOTE this operator is defined in MatrixBase and not as a friend function
// of UniformScaling to fix an internal crash of Intel's ICC
template <typename Derived, typename Scalar>
EIGEN_EXPR_BINARYOP_SCALAR_RETURN_TYPE(Derived, Scalar, internal::scalar_product_op)
operator*(const MatrixBase<Derived>& matrix, const UniformScaling<Scalar>& s) {
  return matrix.derived() * s.factor();
}

inline UniformScaling<float> Scaling(float s) { return UniformScaling<float>(s); }
inline UniformScaling<double> Scaling(double s) { return UniformScaling<double>(s); }
template <typename RealScalar>
inline UniformScaling<std::complex<RealScalar> > Scaling(const std::complex<RealScalar>& s) {
  return UniformScaling<std::complex<RealScalar> >(s);
}

template <typename Scalar>
inline DiagonalMatrix<Scalar, 2> Scaling(const Scalar& sx, const Scalar& sy) {
  return DiagonalMatrix<Scalar, 2>(sx, sy);
}
template <typename Scalar>
inline DiagonalMatrix<Scalar, 3> Scaling(const Scalar& sx, const Scalar& sy, const Scalar& sz) {
  return DiagonalMatrix<Scalar, 3>(sx, sy, sz);
}

template <typename Derived>
inline const DiagonalWrapper<const Derived> Scaling(const MatrixBase<Derived>& coeffs) {
  return coeffs.asDiagonal();
}

template <typename Derived>
inline typename DiagonalWrapper<const Derived>::PlainObject Scaling(MatrixBase<Derived>&& coeffs) {
  return typename DiagonalWrapper<const Derived>::PlainObject(std::move(coeffs.derived()));
}

using AlignedScaling2f = DiagonalMatrix<float, 2>;
using AlignedScaling2d = DiagonalMatrix<double, 2>;
using AlignedScaling3f = DiagonalMatrix<float, 3>;
using AlignedScaling3d = DiagonalMatrix<double, 3>;
 
template <typename Scalar>
template <int Dim>
inline Transform<Scalar, Dim, Affine> UniformScaling<Scalar>::operator*(const Translation<Scalar, Dim>& t) const {
  Transform<Scalar, Dim, Affine> res;
  res.matrix().setZero();
  res.linear().diagonal().fill(factor());
  res.translation() = factor() * t.vector();
  res(Dim, Dim) = Scalar(1);
  return res;
}
 
}  // end namespace Eigen
 
#endif  // EIGEN_SCALING_H