TetrahedronFEMForceField.h

Go to the documentation of this file.

/******************************************************************************
*       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.                                             *
*                                                                             *
* This library 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 Lesser General Public License *
* for more details.                                                           *
*                                                                             *
* You should have received a copy of the GNU Lesser General Public License    *
* along with this library; if not, write to the Free Software Foundation,     *
* 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                             *
******************************************************************************/
#ifndef SOFA_COMPONENT_FORCEFIELD_TETRAHEDRONFEMFORCEFIELD_H
#define SOFA_COMPONENT_FORCEFIELD_TETRAHEDRONFEMFORCEFIELD_H

#include <sofa/core/componentmodel/behavior/ForceField.h>
#include <sofa/core/componentmodel/topology/BaseMeshTopology.h>
#include <sofa/helper/vector.h>
#include <sofa/defaulttype/Vec.h>
#include <sofa/defaulttype/Mat.h>


// corotational tetrahedron from
// @InProceedings{NPF05,
//   author       = "Nesme, Matthieu and Payan, Yohan and Faure, Fran\c{c}ois",
//   title        = "Efficient, Physically Plausible Finite Elements",
//   booktitle    = "Eurographics (short papers)",
//   month        = "august",
//   year         = "2005",
//   editor       = "J. Dingliana and F. Ganovelli",
//   keywords     = "animation, physical model, elasticity, finite elements",
//   url          = "http://www-evasion.imag.fr/Publications/2005/NPF05"
// }


namespace sofa
{

namespace component
{

namespace forcefield
{

using namespace sofa::defaulttype;
using sofa::helper::vector;


template<class DataTypes>
class TetrahedronFEMForceFieldInternalData
{
public:
};


template<class DataTypes>
class TetrahedronFEMForceField : public core::componentmodel::behavior::ForceField<DataTypes>, public virtual core::objectmodel::BaseObject
{
public:
    typedef typename DataTypes::VecCoord VecCoord;
    typedef typename DataTypes::VecDeriv VecDeriv;
    typedef typename DataTypes::VecReal VecReal;
    typedef VecCoord Vector;
    typedef typename DataTypes::Coord Coord;
    typedef typename DataTypes::Deriv Deriv;
    typedef typename Coord::value_type Real;

    typedef core::componentmodel::topology::BaseMeshTopology::index_type Index;
    typedef core::componentmodel::topology::BaseMeshTopology::Tetra Element;
    typedef core::componentmodel::topology::BaseMeshTopology::SeqTetras VecElement;

    enum { SMALL = 0,   
           LARGE = 1,   
           POLAR = 2 }; 

protected:


    typedef VecNoInit<12, Real> Displacement;

    typedef Mat<6, 6, Real> MaterialStiffness;

    typedef Mat<12, 6, Real> StrainDisplacement;

    typedef MatNoInit<3, 3, Real> Transformation; 

    typedef Mat<12, 12, Real> StiffnessMatrix;


    typedef vector<MaterialStiffness> VecMaterialStiffness;
    typedef vector<StrainDisplacement> VecStrainDisplacement;  

    VecMaterialStiffness _materialsStiffnesses;
    VecStrainDisplacement _strainDisplacements;   


    typedef std::pair<int,Real> Col_Value;
    typedef vector< Col_Value > CompressedValue;
    typedef vector< CompressedValue > CompressedMatrix;

    CompressedMatrix _stiffnesses;

    SReal m_potentialEnergy;

    core::componentmodel::topology::BaseMeshTopology* _mesh;
    const VecElement *_indexedElements;
    VecCoord _initialPoints; 

    bool needUpdateTopology;
    
    TetrahedronFEMForceFieldInternalData<DataTypes> data;
    friend class TetrahedronFEMForceFieldInternalData<DataTypes>;

public:
    //For a faster contact handling with simplified compliance
    void getRotation(Transformation& R, unsigned int nodeIdx);


    DataPtr< VecCoord > f_initialPoints; 
    int method;
    Data<std::string> f_method; 
            Real   _poissonRatio;
    DataPtr<Real> f_poissonRatio;
            Real   _youngModulus;
    DataPtr<Real> f_youngModulus;
            VecReal   _localStiffnessFactor;
    DataPtr<VecReal> f_localStiffnessFactor;
            bool   _updateStiffnessMatrix;
    DataPtr<bool> f_updateStiffnessMatrix;
            bool   _assembling;
    DataPtr<bool> f_assembling;

    TetrahedronFEMForceField()
    : _mesh(NULL)
    , _indexedElements(NULL)
    , needUpdateTopology(false)
    , f_initialPoints(initDataPtr(&f_initialPoints, &_initialPoints, "initialPoints", "Initial Position"))
    , f_method(initData(&f_method,std::string("large"),"method","\"small\", \"large\" (by QR) or \"polar\" displacements"))
    ,  _poissonRatio((Real)0.45f)
    , f_poissonRatio(initDataPtr(&f_poissonRatio,&_poissonRatio,"poissonRatio","FEM Poisson Ratio"))
    ,  _youngModulus((Real)5000)
    , f_youngModulus(initDataPtr(&f_youngModulus,&_youngModulus,"youngModulus","FEM Young Modulus"))
    , f_localStiffnessFactor(initDataPtr(&f_localStiffnessFactor,&_localStiffnessFactor,"localStiffnessFactor","Allow specification of different stiffness per element. If there are N element and M values are specified, the youngModulus factor for element i would be localStiffnessFactor[i*M/N]"))
    ,  _updateStiffnessMatrix(false)
    , f_updateStiffnessMatrix(initDataPtr(&f_updateStiffnessMatrix,&_updateStiffnessMatrix,"updateStiffnessMatrix",""))
    ,  _assembling(false)
    , f_assembling(initDataPtr(&f_assembling,&_assembling,"assembling",""))
    {}

    void parse(core::objectmodel::BaseObjectDescription* arg);

    void setPoissonRatio(Real val) { this->f_poissonRatio.setValue(val); }

    void setYoungModulus(Real val) { this->f_youngModulus.setValue(val); }

    void setMethod(std::string methodName)
    {     
      if (methodName == "small")    this->setMethod(SMALL);
      else if (methodName  == "polar")  this->setMethod(POLAR);
      else  
      {
    if (methodName != "large") 
      std::cerr << "unknown method: large method will be used. Remark: Available method are \"small\", \"polar\", \"large\" \n";
    this->setMethod(LARGE);
      }     
    }
    
    void setMethod(int val) 
    { 
      method = val; 
      switch(val)
      {
        case SMALL: f_method.setValue("small"); break;    
        case POLAR: f_method.setValue("polar"); break;
        default   : f_method.setValue("large"); 
      };
    }

    void setUpdateStiffnessMatrix(bool val) { this->f_updateStiffnessMatrix.setValue(val); }

    void setComputeGlobalMatrix(bool val) { this->f_assembling.setValue(val); }

    virtual void init();
    virtual void reinit();

    virtual void addForce (VecDeriv& f, const VecCoord& x, const VecDeriv& v);

    virtual void addDForce (VecDeriv& df, const VecDeriv& dx, double kFactor, double bFactor);

    virtual double getPotentialEnergy(const VecCoord& x);

    virtual void addKToMatrix(sofa::defaulttype::BaseMatrix *, SReal, unsigned int &);

    void draw();

  protected:

    void computeStrainDisplacement( StrainDisplacement &J, Coord a, Coord b, Coord c, Coord d );
    Real peudo_determinant_for_coef ( const Mat<2, 3, Real>&  M );

    void computeStiffnessMatrix( StiffnessMatrix& S,StiffnessMatrix& SR,const MaterialStiffness &K, const StrainDisplacement &J, const Transformation& Rot );

    void computeMaterialStiffness(int i, Index&a, Index&b, Index&c, Index&d);

    void computeForce( Displacement &F, const Displacement &Depl, const MaterialStiffness &K, const StrainDisplacement &J );
    void computeForce( Displacement &F, const Displacement &Depl, const MaterialStiffness &K, const StrainDisplacement &J, double fact );

    void initSmall(int i, Index&a, Index&b, Index&c, Index&d);
    void accumulateForceSmall( Vector& f, const Vector & p, typename VecElement::const_iterator elementIt, Index elementIndex );
    void applyStiffnessSmall( Vector& f, const Vector& x, int i=0, Index a=0,Index b=1,Index c=2,Index d=3, double fact=1.0  );

    vector<helper::fixed_array<Coord,4> > _rotatedInitialElements;   
    vector<Transformation> _rotations;
    vector<Transformation> _initialRotations;
    void initLarge(int i, Index&a, Index&b, Index&c, Index&d);
    void computeRotationLarge( Transformation &r, const Vector &p, const Index &a, const Index &b, const Index &c);
    void accumulateForceLarge( Vector& f, const Vector & p, typename VecElement::const_iterator elementIt, Index elementIndex );
    void applyStiffnessLarge( Vector& f, const Vector& x, int i=0, Index a=0,Index b=1,Index c=2,Index d=3, double fact=1.0 );

    vector<Transformation>  _initialTransformation;
    vector<unsigned int> _rotationIdx;
    void initPolar(int i, Index&a, Index&b, Index&c, Index&d);
    void accumulateForcePolar( Vector& f, const Vector & p, typename VecElement::const_iterator elementIt, Index elementIndex );
    void applyStiffnessPolar( Vector& f, const Vector& x, int i=0, Index a=0,Index b=1,Index c=2,Index d=3, double fact=1.0  );
    
    void handleTopologyChange()
    {
        needUpdateTopology = true;
    }
};

} // namespace forcefield

} // namespace component

} // namespace sofa

#endif