DampVelocitySolver.cpp

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/******************************************************************************
*       SOFA, Simulation Open-Framework Architecture, version 1.0 beta 3      *
*                (c) 2006-2008 MGH, INRIA, USTL, UJF, CNRS                    *
*                                                                             *
* This library 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; either version 2.1 of the License, or (at     *
* your option) any later version.                                             *
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License *
* for more details.                                                           *
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* You should have received a copy of the GNU Lesser General Public License    *
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA.          *
*******************************************************************************
*                               SOFA :: Modules                               *
*                                                                             *
* Authors: The SOFA Team and external contributors (see Authors.txt)          *
*                                                                             *
* Contact information: contact@sofa-framework.org                             *
******************************************************************************/
#include <sofa/component/odesolver/DampVelocitySolver.h>
#include <sofa/core/ObjectFactory.h>
#include <math.h>
#include <iostream>

using std::cerr;
using std::endl;

namespace sofa
{

namespace component
{

namespace odesolver
{

using namespace sofa::defaulttype;
using namespace core::componentmodel::behavior;

int DampVelocitySolverClass = core::RegisterObject("Reduce the velocities")
    .add< DampVelocitySolver >()
    .addAlias("DampVelocity")
    ;

SOFA_DECL_CLASS(DampVelocity);

DampVelocitySolver::DampVelocitySolver()
  : rate( initData( &rate, 0.99, "rate", "Factor used to reduce the velocities. Typically between 0 and 1.") )
    , threshold( initData( &threshold, 0.0, "threshold", "Threshold under which the velocities are canceled.") )
  {}

void DampVelocitySolver::solve(double dt)
{
    MultiVector vel(this, VecId::velocity());
    bool printLog = f_printLog.getValue();

    if( printLog )
    {
        cerr<<"DampVelocitySolver, dt = "<< dt <<endl;
        cerr<<"DampVelocitySolver, initial v = "<< vel <<endl;
    }

    addSeparateGravity(dt); // v += dt*g . Used if mass wants to added G separately from the other forces to v.

    vel.teq( exp(-rate.getValue()*dt) );
    if( threshold.getValue() != 0.0 )
      vel.threshold( threshold.getValue() );
    
    if( printLog )
    {
        cerr<<"DampVelocitySolver, final v = "<< vel <<endl;
    }
}

} // namespace odesolver

} // namespace component

} // namespace sofa