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//  Rigid_Body.h - 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
//  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 _RIGID_BODY_H_
#define _RIGID_BODY_H_

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

#include <vector>

namespace Vamos_Body
  struct Contact_Parameters
      Contact_Parameters ();

      Particle* mp_contact_point;
      double m_distance;
      Vamos_Geometry::Three_Vector m_normal;
      Vamos_Geometry::Material_Handle m_material;

  //* A rigid body.
  class Rigid_Body : public Frame
      // The body's initial position vector, used by reset ().
      Vamos_Geometry::Three_Vector m_initial_position;

      Vamos_Geometry::Three_Vector m_last_position;

      // The velocity of the center of mass.
      Vamos_Geometry::Three_Vector m_cm_velocity;

      Vamos_Geometry::Three_Vector m_last_cm_velocity;

      Vamos_Geometry::Three_Vector m_last_velocity;

      Vamos_Geometry::Three_Matrix m_last_orientation;

      Vamos_Geometry::Three_Vector m_last_ang_velocity;

      // The acceleration due to gravity, distance/time^2.  The units
      // determine the distance and time units used in the rest of the
      // simulation.
      Vamos_Geometry::Three_Vector m_gravity;

      // The elapsed time since the last time step.
      double m_delta_time;

      // The total mass of the body.
      double m_mass;

      // Common code for the two reset () methods.
      void private_reset ();

      Contact_Parameters m_contact_parameters;
      bool valid;

      // The inertia tensor for the body.
      Vamos_Geometry::Inertia_Tensor m_inertia;

      // A vector of pointers to the force and torque producers that
      // make up the body
      std::vector <Particle*> m_particles;

      // The position of the center of mass of the body relative to the
      // origin of the body.
      Vamos_Geometry::Three_Vector m_body_cm;
      Vamos_Geometry::Three_Vector m_last_body_cm;

      //** Constructors

      // Specify the position and orientation of the body.
      Rigid_Body (const Vamos_Geometry::Three_Vector& pos, 
                const Vamos_Geometry::Three_Matrix& orient);

      // Specify the position, the orientation is the same as the parent.
      Rigid_Body (const Vamos_Geometry::Three_Vector& pos);

      // The body is coincident with the parent.
      Rigid_Body ();

      //** Destructor
      virtual ~Rigid_Body ();

    Vamos_Geometry::Three_Vector center_of_mass () const { return m_body_cm; }

      // Return the position of the center of mass of the body with
      // respect to the world.
      Vamos_Geometry::Three_Vector cm_position ();

      // Provide access to the frame's position method.  Return the
      // origin of the body.
      Vamos_Geometry::Three_Vector position () const 
      { return Frame::position (); }
      bool IsValid() {return valid;}

      // Return the contact position of the particle with respect to the
      // world.
      Vamos_Geometry::Three_Vector contact_position (Particle* contact_point);
      Vamos_Geometry::Three_Vector last_contact_position (Particle* contact_point);
      // Return the smallest contact position z-value of the particles.
      double lowest_contact_position () const;

      // Add a particle to the body.
      void add_particle (Particle* const comp) 
      { m_particles.push_back (comp); } 

      // Calculate the center of mass, the ineritia tensor, and its
      // inverse.
      void update_center_of_mass ();

      // Provide access to the particles.
      std::vector <Particle*>& particles () { return m_particles; }

      void find_forces ();

      // Advance the body in time by TIME.
      void propagate (double time);
      void propagate_contact ();

      // Undo the last propagation.
      void rewind ();

      // Finish the timestep.
      void end_timestep ();

      // Called by the world to tell the body what the acceleration due
      // to gravity is.
      void gravity (const Vamos_Geometry::Three_Vector& grav) 
      { m_gravity = grav; }

      // Return the velocity of the particle in the parent frame.
      // With no argument, return the velocity of the origin of the body
      // frame.
      Vamos_Geometry::Three_Vector velocity (Particle* particle);

      // Return the velocity of the center of mass.
      Vamos_Geometry::Three_Vector cm_velocity () const { return m_cm_velocity; }
      Vamos_Geometry::Three_Vector cm_last_velocity () const { return m_last_cm_velocity; }

      // Set the velocity of the center of mass.
      void cm_velocity (Vamos_Geometry::Three_Vector vel) 
      { m_cm_velocity = vel;}

      // Handle a collision.
      void contact (Particle* contact_point, 
                          double distance,
                          const Vamos_Geometry::Three_Vector& normal,
                          Vamos_Geometry::Material_Handle material);

      // Transform the wind into the body frame and send it to the 
      // aerodynamic device.
      void wind (Particle* aero_device, 
                     const Vamos_Geometry::Three_Vector& wind_vector, 
                     double density);

      // Return the total mass.
      double mass () const { return m_mass; }

      // This function is defined by subclasses that work with a
      // graphics system.
      virtual void draw () {};

      // Return the body to its initial state at its initial position.
      virtual void reset ();

      // Return the body to its initial state at a particular position and
      // orientation.
      virtual void reset (const Vamos_Geometry::Three_Vector& position, 
                                    const Vamos_Geometry::Three_Matrix& orientation);
      void set_position(Vamos_Geometry::Three_Vector np) {place(np);m_last_position = np;}
      void set_orientation(Vamos_Geometry::Three_Matrix no) {orient(no);m_last_orientation = no;}
      void set_angvel(Vamos_Geometry::Three_Vector nav) {set_ang_velocity(nav); m_last_ang_velocity = nav;}
      void set_velocity(Vamos_Geometry::Three_Vector vel) {m_cm_velocity = vel; m_velocity = vel; m_last_velocity = vel; m_last_cm_velocity = vel;}
      //set current state to last state
      void roll_back();
      //set velocities to zero
      void kill_vel();
      //respond to a single point contact
      void single_point_contact(Vamos_Geometry::Three_Vector worldposition,
            double distance,
            Vamos_Geometry::Three_Vector normal,
            Vamos_Geometry::Material_Handle material, double time);

#endif // !_BODY_H_

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