include/vamos/body/Particle.h

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//      Particle.h - a massive particle which is part of a rigid body.
//
//  Copyright (C) 2001--2002 Sam Varner
//
//  This file is part of Vamos Automotive Simulator.
//
//  This program 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.
//
//  This program 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 this program; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

#ifndef _PARTICLE_H_
#define _PARTICLE_H_

#include <vamos/geometry/Three_Vector.h>
#include <vamos/geometry/Three_Matrix.h>
#include <vamos/geometry/Inertia_Tensor.h>
#include <vamos/geometry/Material.h>
#include <vamos/body/Frame.h>
#include <vamos/body/Exerter.h>

namespace Vamos_Body
{
  //* A Particle is a massive particle which is part of a rigid body.
  // It has position and orientation information inherited from Frame.
  // The parent frame is the rigid body's.  A Particle can exert
  // forces and torques on the rigid body because it is derived from
  // Component.
  class Particle : public Frame, public Exerter
  {
  protected:
        // The mass of the particle.
        double m_mass;

        // Material properties for the particle.
        Vamos_Geometry::Material_Handle m_material;

  public:
        //** Constructors

        // Specify position and orientation.
        Particle (double mass, const Vamos_Geometry::Three_Vector& position, 
                          const Vamos_Geometry::Three_Matrix& orientation);

        // Take the parent's orientation.
        Particle (double mass, const Vamos_Geometry::Three_Vector& position);

        // The particle's frame is coincident with the parent's.
        Particle (double mass = 0.0);

        //** Destructor
        virtual ~Particle () {};

        // Return the force exerted on the rigid body in the body's frame.
        virtual Vamos_Geometry::Three_Vector force () const
        { return rotate_out (m_force); }

        // Return the impulse exerted on the rigid body in the body's
        // frame.
        virtual Vamos_Geometry::Three_Vector impulse () const
        { return rotate_out (m_impulse); }

        // Return the torque exerted on the rigid body in the body's frame.
        virtual Vamos_Geometry::Three_Vector torque () const
        { return rotate_out (m_torque); }

        // Classes derived from Particle may lie about their positions
        // for collisions...
        virtual Vamos_Geometry::Three_Vector contact_position () const 
        { return position (); }

        // ...for exerting forces and impulses...
        virtual Vamos_Geometry::Three_Vector force_position () const 
        { return position (); }

        // ...for exerting torques...
        virtual Vamos_Geometry::Three_Vector torque_position () const 
        { return position (); }

        // ...or for constructing the inertia tensor of the rigid body.
        virtual Vamos_Geometry::Three_Vector mass_position () const 
        { return position (); }

        virtual double contact (const Vamos_Geometry::Three_Vector& position,
                                                        const Vamos_Geometry::Inertia_Tensor& inertia,
                                                        const Vamos_Geometry::Three_Vector& velocity,
                                                        double distance,
                                                        const Vamos_Geometry::Three_Vector& normal,
                                                        const Vamos_Geometry::Three_Vector& ang_velocity,
                                                        Vamos_Geometry::Material_Handle) 
        { return 0.0; }

        // Return the particle's mass.
        double mass () const { return m_mass; }

        virtual bool single_contact () const { return true; }
        virtual void wind (const Vamos_Geometry::Three_Vector& wind_vector, 
                                           double density) 
        {};

        // Return the material properties.
        const Vamos_Geometry::Material_Handle& material () const 
        { return m_material; }
  };
}

#endif // not _PARTICLE_H_

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