JRotation2D.hh

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#ifndef __JROTATION2D__
#define __JROTATION2D__

#include <cmath>

#include "JGeometry2D/JMatrix2D.hh"
#include "JGeometry2D/JAngle2D.hh"


/**
 * \author mdejong
 */

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

namespace JGEOMETRY2D {


  /**
   * Rotation matrix
   */
  class JRotation2D :
    public JMatrix2D
  {
  public:
    /**
     * Default constructor (= identity matrix).
     */
    JRotation2D() :
      JMatrix2D()
    {
      setIdentity();
    }


    /**
     * Constructor.
     * The rotation is around the origin and anti-clockwise.
     *
     * \param  dir        direction
     */
    JRotation2D(const JAngle2D& dir) :
      JMatrix2D()
    {
      const double cp = cos(dir.getPhi());
      const double sp = sin(dir.getPhi());

      a00 = cp;  a01 = -sp;
      a10 = sp;  a11 =  cp;
    }


    /**
     * Get rotation.
     *
     * \return            rotation
     */
    const JRotation2D& getRotation() const
    {
      return static_cast<const JRotation2D&>(*this);
    }
    

    /**
     * Transpose.
     */
    JRotation2D& transpose()
    {
      JMatrix2D::transpose();

      return *this;
    }


    /**
     * Matrix multiplication.
     *
     * \param  A        matrix
     * \return          this * A
     */
    JRotation2D& mul(const JRotation2D& A)
    {
      JMatrix2D::mul(A);

      return *this;
    }


    /**
     * Rotate.
     *
     * \param  __x      x value
     * \param  __y      y value
     */
    void rotate(double& __x, double& __y) const
    {
      const double x = a00 * __x  +  a01 * __y;
      const double y = a10 * __x  +  a11 * __y;

      __x = x;
      __y = y;
    }


    /**
     * Rotate back.
     *
     * \param  __x      x value
     * \param  __y      y value
     */
    void rotate_back(double& __x, double& __y) const
    {
      const double x = a00 * __x  +  a10 * __y;
      const double y = a01 * __x  +  a11 * __y;

      __x = x;
      __y = y;
    }
  };
}

#endif