Reference Manual: CGAL_Min_ellipse_2

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Traits Class Adapter for 2D Smallest Enclosing Ellipse to 2D Cartesian Points (CGAL_Min_ellipse_2_adapterC2)

Definition

The class CGAL_Min_ellipse_2_adapterC2<PT,DA> interfaces the 2D optimisation algorithm for smallest enclosing ellipses with the point class PT. The data accessor DA [KW97] is used to access the x- and y-coordinate of PT, i.e. PT is supposed to have a Cartesian representation of its coordinates.

#include <CGAL/Min_ellipse_2_adapterC2.h>

Types

CGAL_Min_ellipse_2_adapterC2<PT,DA>::DA
Data accessor for Cartesian coordinates.

CGAL_Min_ellipse_2_adapterC2<PT,DA>::Point
Point type.

CGAL_Min_ellipse_2_adapterC2<PT,DA>::Ellipse
Ellipse type.

Creation

CGAL_Min_ellipse_2_adapterC2<PT,DA> adapter ( DA da = DA());

CGAL_Min_ellipse_2_adapterC2<PT,DA> adapter ( CGAL_Min_ellipse_2_adapterC2<PT,DA>);

Example

The following example illustrates the use of the traits class adapters with your own point class. For the sake of simplicity, we expect a point class with Cartesian double coordinates and access functions x() and y(). Based on this we show how to implement and use data accessors.

Note: In this release correct results are only guaranteed if exact arithmetic is used, so this example (using inexact floating-point arithmetic) is only intended to illustrate the techniques.

#include <CGAL/Min_ellipse_2_adapterC2.h>
#include <CGAL/Min_ellipse_2.h>

// your own point class (Cartesian)
class PtC {
    // ...
  public:
    PtC( double x, double y);
    double  x( ) const;
    double  y( ) const;
    // ...
};

// the data accessor for PtC
class PtC_DA {
  public:
    typedef  double  FT;
    void  get( const PtC& p, double& x, double& y) const {
        x = p.x(); y = p.y();
    }
    double  get_x( const PtC& p) const { return( p.x()); }
    double  get_y( const PtC& p) const { return( p.y()); }
    void  set( PtC& p, double x, double y) const { p = PtC( x, y); }
};

// some typedefs
typedef  CGAL_Min_ellipse_2_adapterC2 < PtC, PtC_DA >  AdapterC;
typedef  CGAL_Min_ellipse_2 < AdapterC >               Min_ellipse;

// do something with Min_ellipse
Min_ellipse   me( /*...*/ );

Next: Class declaration of CGAL_Min_ellipse_2_adapterH2<PT,DA>