ReferenceFrame3D.h

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/**
 *  \file IMP/algebra/ReferenceFrame3D.h
 *  \brief A reference frame in 3D.
 *
 *  Copyright 2007-2017 IMP Inventors. All rights reserved.
 *
 */

#ifndef IMPALGEBRA_REFERENCE_FRAME_3D_H
#define IMPALGEBRA_REFERENCE_FRAME_3D_H

#include <IMP/algebra/algebra_config.h>
#include "Transformation3D.h"

IMPALGEBRA_BEGIN_NAMESPACE

//! A reference frame in 3D.
/**
    \geometry
*/
class IMPALGEBRAEXPORT ReferenceFrame3D {
  Transformation3D tr_;
  mutable bool has_inverse_;
  mutable Transformation3D tri_;
  const Transformation3D &get_inverse() const {
    if (!has_inverse_) {
      tri_ = tr_.get_inverse();
      has_inverse_ = true;
    }
    return tri_;
  }

 public:
  IMP_CXX11_DEFAULT_COPY_CONSTRUCTOR(ReferenceFrame3D);
  //! Create the default reference frame
  /** That is, the origin with x,y,z axis as the principal axes. */
  ReferenceFrame3D()
      : tr_(get_identity_transformation_3d()), has_inverse_(true), tri_(tr_) {}

  //! A reference frame specified by a transformation matrix
  /** Constructs a reference frame using transformation tr

      @param tr a transformation from local coordinates in this
                constructed reference frame to the global coordinates
                (equiv., tr brings the origin of the global frame
                 to the origin of this frame, in global coordinates),
  */
  explicit ReferenceFrame3D(const Transformation3D &tr)
      : tr_(tr), has_inverse_(false) {}
  ~ReferenceFrame3D();
  //! Get the transformation that brings the origin of the global reference
  //! frame to the origin of this frame (both in global coordinates).
  const Transformation3D &get_transformation_to() const { return tr_; }
  //! Get the transformation from the origin of this reference frame
  //! to the origin of the global frame (both in global coordinates).
  const Transformation3D &get_transformation_from() const {
    return get_inverse();
  }
  //! Assume the input vector is in local coordinates and transform
  //! it to global ones.
  Vector3D get_global_coordinates(const Vector3D &v) const {
    return tr_.get_transformed(v);
  }
  //! Assume the input vector is in global coordinates and get the local
  //! coordinates.
  Vector3D get_local_coordinates(const Vector3D &v) const {
    return get_inverse().get_transformed(v);
  }
  //! Assume the input vector is in local coordinates and transform
  //! it to global ones.
  ReferenceFrame3D get_global_reference_frame(const ReferenceFrame3D &v) const {
    return ReferenceFrame3D(tr_ * v.tr_);
  }
  //! Assume the input vector is in global coordinates and get the local
  //! coordinates.
  ReferenceFrame3D get_local_reference_frame(const ReferenceFrame3D &v) const {
    return ReferenceFrame3D(get_inverse() * v.tr_);
  }
  IMP_SHOWABLE_INLINE(ReferenceFrame3D, { out << tr_; });
};

IMP_VALUES(ReferenceFrame3D, ReferenceFrame3Ds);

inline ReferenceFrame3D get_transformed(const ReferenceFrame3D &rf,
                                        const Transformation3D &tr) {
  return ReferenceFrame3D(tr * rf.get_transformation_to());
}

inline Transformation3D get_transformation_from_first_to_second(
    const ReferenceFrame3D &a, const ReferenceFrame3D &b) {
  return b.get_transformation_to() * a.get_transformation_from();
}

IMPALGEBRA_END_NAMESPACE
#endif /* IMPALGEBRA_REFERENCE_FRAME_3D_H */