/*   []----------------------------------------[]
      |                Gravity.h               |
     []----------------------------------------[]
      |                                        |
      |   AUTHOR:    MFSomers 2005.            |
      |   USE:       Defines a gravitational   |
      |              type interaction...       |
      |                                        |
     []----------------------------------------[]
*/

// Copyright (C) 2005 M.F. Somers, Theoretical Chemistry Department, Leiden University
//
// This is free software; you can redistribute it and/or modify it under the terms of
// the GNU Lesser General Public License as published by the Free Software Foundation.
//
// http://www.gnu.org/licenses/lgpl.txt

#if !defined(__GRAVITY_INCLUDED__)

#define __GRAVITY_INCLUDED__

#include "Global.h"
#include "Vector.h"
#include "Constants.h"
#include "ClassicalDynamics.h"
#include "PointPair.h"

/* --------------------------------------------------------- */
/* Defines a gravitational pointpair interaction between particles */

class   GravitationalInteraction;
typedef GravitationalInteraction *GravitationalInteractionPointer;

class GravitationalInteraction : public PointPairInteraction
                           {
			    public:
			     
			    inline GravitationalInteraction( double TheFactor = CONST_GRAVITATIONAL_CONST,
			                       unsigned int TheId = GET_NEW_ID, Vector *UsePeriodicBox = NULL ) : PointPairInteraction( TheId, UsePeriodicBox )
			    {
			     InteractionFactor = TheFactor;
			     Type = AGravitationalInteraction;
			    };
			    inline GravitationalInteraction( GravitationalInteraction& I ) : PointPairInteraction( I )
			    {
			     InteractionFactor = I.InteractionFactor;
			    }

			    virtual GravitationalInteraction& operator=( GravitationalInteraction& I )
			    {
			     if( &I == &(*this) ) return( (*this) );
			     PointPairInteraction::operator=( I );
			     InteractionFactor = I.InteractionFactor;
			     return( (*this) );
			    }			    
			    virtual GravitationalInteractionPointer Clone()
                            {
	                     return( new GravitationalInteraction( (*this) ) );
	                    }
		            virtual GravitationalInteractionPointer Create( double TheFactor = CONST_GRAVITATIONAL_CONST, 
			                                                    unsigned int TheId = GET_NEW_ID, Vector *UsePeriodicBox = NULL )
	                    {
	                     return( new GravitationalInteraction( TheFactor, TheId, UsePeriodicBox ) );
	                    }		
			    
			    virtual double PointPairPotential( Particle& P1, Particle& P2 );
			    virtual Vector PointPairForce( Particle& P1, Particle& P2 );
			    
			    double InteractionFactor;
			   };
			   
/* --------------------------------------------------------- */

#endif