JAxis2D.hh

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#ifndef __JAXIS2D__
#define __JAXIS2D__

#include <istream>
#include <ostream>

#include "JIO/JSerialisable.hh"
#include "JGeometry2D/JPosition2D.hh"
#include "JGeometry2D/JDirection2D.hh"
#include "JGeometry2D/JRotation2D.hh"
#include "JGeometry2D/JSegment2D.hh"


/**
 * \author mdejong
 */

namespace JGEOMETRY2D {}
namespace JPP { using namespace JGEOMETRY2D; }

namespace JGEOMETRY2D {

  using JIO::JReader;
  using JIO::JWriter;


  /**
   * Axis object.
   *
   * An axis object consists of a position and a direction.
   */
  class JAxis2D : 
    public JPosition2D,
    public JDirection2D
  {
  public:
    /**
     * Default constructor.
     */
    JAxis2D() :
      JPosition2D (),
      JDirection2D()
    {}


    /**
     * Constructor.
     *
     * \param  pos          position
     */
    JAxis2D(const JVector2D& pos) :
      JPosition2D (pos), 
      JDirection2D()
    {}


    /**
     * Constructor.
     *
     * \param  pos          position
     * \param  dir          direction
     */
    JAxis2D(const JVector2D& pos,
            const JVersor2D& dir) :
      JPosition2D (pos), 
      JDirection2D(dir)
    {}


    /**
     * Constructor.
     *
     * \param  segment      line segment
     */
    JAxis2D(const JSegment2D& segment) :
      JPosition2D (segment.first),
      JDirection2D(segment.second - segment.first)
    {}

    
    /**
     * Get axis.
     *
     * \return              axis
     */
    const JAxis2D& getAxis() const 
    { 
      return *this; 
    }

    
    /**
     * Set axis.
     *
     * \param  axis         axis
     */
    void setAxis(const JAxis2D& axis)
    { 
      *this = axis; 
    }


    /**
     * Negate axis.
     *
     * \return              this axis
     */
    JAxis2D& negate()
    {
      static_cast<JPosition2D&> (*this).negate();
      static_cast<JDirection2D&>(*this).negate();

      return *this;
    }
   

    /**
     * Move vertex along this axis.
     *
     * \param  step         step
     */
    void move(const double step)
    {
      getPosition() += step * JVector2D(getDirection());    
    }


    /**
     * Test whether this axis and given line segment intersect.
     *
     * \param  segment      line segment
     * \return              true if axis and line segment intersect; else false
     */
    bool intersects(const JSegment2D& segment) const
    {
      if (getCCW(segment.first, this->getPosition(), segment.second)) 
        return (this->getDirection().getPerpDot(segment.first  - this->getPosition()) > 0.0 && 
                this->getDirection().getPerpDot(segment.second - this->getPosition()) < 0.0);
      else
        return (this->getDirection().getPerpDot(segment.first  - this->getPosition()) < 0.0 && 
                this->getDirection().getPerpDot(segment.second - this->getPosition()) > 0.0);
    }


    /**
     * Get intersection of two axes.
     *
     * \param  axis         axis
     * \param  precision    precision
     * \return              longitudinal position
     */
    double getIntersection(const JAxis2D& axis, const double precision = 1.0e-8) const
    {
      const double gp = this->getDirection().getPerpDot(axis.getDirection());

      if (fabs(gp) > precision)
        return axis.getDirection().getPerpDot(this->getPosition() - axis.getPosition()) / gp;
      else
        return this->getDistance(axis.getPosition());
    }


    /**
     * Get squared of distance to point.
     *
     * \param  point        point
     * \return              square of distance
     */
    double getDistanceSquared(const JVector2D& point) const
    {
      JVector2D D(this->getDirection());

      const JVector2D U(point - this->getPosition());

      const double u = D.getDot(U);

      D.mul(u);
      D.sub(U);

      return D.getLengthSquared();
    }


    /**
     * Get distance to point.
     *
     * \param  point        point
     * \return              distance
     */
    double getDistance(const JVector2D& point) const
    {
      return sqrt(getDistanceSquared(point));
    }


    /**
     * Rotate axis.
     *
     * \param  R            rotation matrix
     * \return              this axis
     */
    JAxis2D& rotate(const JRotation2D& R)
    {
      static_cast<JPosition2D&> (*this).rotate(R);
      static_cast<JDirection2D&>(*this).rotate(R);

      return *this;
    }


    /**
     * Rotate back axis.
     *
     * \param  R            rotation matrix
     * \return              this axis
     */
    JAxis2D& rotate_back(const JRotation2D& R)
    {
      static_cast<JPosition2D&> (*this).rotate_back(R);
      static_cast<JDirection2D&>(*this).rotate_back(R);

      return *this;
    }


    /**
     * Read axis from input.
     *
     * \param  in           input stream
     * \param  axis         axis
     * \return              input stream
     */
    friend inline std::istream& operator>>(std::istream& in, JAxis2D& axis)
    {
      in >> static_cast<JPosition2D&> (axis);
      in >> static_cast<JDirection2D&>(axis);

      return in;
    }


    /**
     * Write axis to output.
     *
     * \param  out          output stream
     * \param  axis         axis
     * \return              output stream
     */
    friend inline std::ostream& operator<<(std::ostream& out, const JAxis2D& axis)
    {
      out << static_cast<const JPosition2D&> (axis);
      out << ' ';
      out << static_cast<const JDirection2D&>(axis);

      return out;
    }


    /**
     * Read axis from input.
     *
     * \param  in           reader
     * \param  axis         axis
     * \return              reader
     */
    friend inline JReader& operator>>(JReader& in, JAxis2D& axis)
    {
      in >> static_cast<JPosition2D&> (axis);
      in >> static_cast<JDirection2D&>(axis);

      return in;
    }


    /**
     * Write axis to output.
     *
     * \param  out          writer
     * \param  axis         axis
     * \return              writer
     */
    friend inline JWriter& operator<<(JWriter& out, const JAxis2D& axis)
    {
      out << static_cast<const JPosition2D&> (axis);
      out << static_cast<const JDirection2D&>(axis);

      return out;
    }
  };
}

#endif