---

distance_constraint.h

//$Header: /home/ben/Mapper/include/RCS/distance_constraint.h,v 6.4 2002/07/07 18:23:15 ben Exp $
#ifndef DISTANCE_CONSTRAINT_H
#define DISTANCE_CONSTRAINT_H
// Copyright Benedict Adamson 2002.
// This file is part of Mapper.

// Mapper is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.

// Mapper is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Mapper; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

#include "assoc.h"
#include "constraint.h"



class distance_constraint
   :public constraint
{
   public: //Constructors and destructors.

      distance_constraint(
         const double u,
         const double d
         );

      virtual ~distance_constraint(void);

   public: //Attributes

      virtual void energy(
         const double tol,
         const vector< vector2 > &p,
         double &e, //output
         vector< vector2 > &dedp //output
         ) const;

      inline double wanted_distance(void) const;

   public: //Messages

      void wanted_distance(
         const double d
         );

   private: //State

      double wanted_distance_;

      friend void assoc(
         distance_constraint &c,
         vector2 &p0,
         vector2 &p1
         );

      friend void unassoc(
         distance_constraint &c
         );

};



inline double distance_constraint::wanted_distance(void) const
{
   //The expected separation of the two constrained points.
   return this->wanted_distance_;
}


      
#endif

---