physics/MassProperties

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/****************************************************************************
  Copyright (C)1996 David Jung <opensim@pobox.com>

  This program/file 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. (http://www.gnu.org)
  
  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
  
  $Id: MassProperties 1031 2004-02-11 20:46:36Z jungd $
  $Revision: 1.2 $
  $Date: 2004-02-11 15:46:36 -0500 (Wed, 11 Feb 2004) $
  $Author: jungd $
 
****************************************************************************/

#ifndef _PHYSICS_MASSPROPERTIES_
#define _PHYSICS_MASSPROPERTIES_

#include <physics/physics>
#include <base/Object>
#include <base/Matrix4>
#include <base/Point3>
#include <gfx/TriangleContainer>


namespace physics {

class Material;


class MassProperties : public base::Object
{
public:
  MassProperties();
  MassProperties(const MassProperties& mp) 
    : mass(mp.mass), centerOfMass(mp.centerOfMass),
      _Ibody(mp._Ibody), _IbodyInv(mp._IbodyInv) {}
  MassProperties(const gfx::TriangleContainer& triangles, ref<const Material> material);
  virtual ~MassProperties() {}

  virtual String className() const { return String("MassProperties"); }

  const Matrix3& Ibody() const { return _Ibody; }
  const Matrix3& IbodyInv() const { return _IbodyInv; }
  
  void setIbody(const Matrix3& Ibody);
  
  Real         mass;            // mass
  base::Point3  centerOfMass;    // (in body coords.)

protected:
  base::Matrix3 _Ibody;          // Inertia tensor in body coords.
  base::Matrix3 _IbodyInv;       // Inverse Inertia tensor in body coords.
        

  // helpers for computing the mass properties from the triangle set of a tesselatable
  // See the paper:
  //  "Fast and Accurate Computation of Polyhedral Mass Properties"
  //    Brian Mirtich, University of California at Berkeley
  
  void computeMassProperties(const gfx::TriangleContainer& triangles, ref<const Material> material);

  class VolData;
  class WTriangle;

  void compVolumeIntegrals(const gfx::TriangleContainer& triangles, VolData& v);
  void compFaceIntegrals(const WTriangle& t, VolData& v);
  void compProjectionIntegrals(const WTriangle& t, VolData& v);
};


std::ostream& operator<<(std::ostream& out, const MassProperties& mp); // Output

} // physics

#endif

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