TetrahedralCorotationalFEMForceField.h

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/******************************************************************************
*       SOFA, Simulation Open-Framework Architecture, version 1.0 beta 3      *
*                (c) 2006-2008 MGH, INRIA, USTL, UJF, CNRS                    *
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*                               SOFA :: Modules                               *
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#ifndef SOFA_COMPONENT_FORCEFIELD_TETRAHEDRALCOROTATIONALFEMFORCEFIELD_H
#define SOFA_COMPONENT_FORCEFIELD_TETRAHEDRALCOROTATIONALFEMFORCEFIELD_H

#include <sofa/core/componentmodel/behavior/ForceField.h>
#include <sofa/component/MechanicalObject.h>
#include <sofa/component/topology/TetrahedronData.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;
using namespace sofa::component::topology;



template<class DataTypes>
class TetrahedralCorotationalFEMForceField : 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;


    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;

    
    class TetrahedronInformation
    {
    public:
        MaterialStiffness materialMatrix;
        StrainDisplacement strainDisplacementMatrix;
        helper::fixed_array<Coord,4> rotatedInitialElements;
        Transformation rotation;
        Transformation initialTransformation;

        TetrahedronInformation() {
        }
    };
    TetrahedronData<TetrahedronInformation> tetrahedronInfo;


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

    CompressedMatrix _stiffnesses;

    double m_potentialEnergy;
    
    sofa::core::componentmodel::topology::BaseMeshTopology* _topology;

public:
   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;

    TetrahedralCorotationalFEMForceField()
    : 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(int val) { method = val; }

    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);

    virtual double getPotentialEnergy(const VecCoord& x);

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

    // handle topological changes
    virtual void handleTopologyChange();

    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 initSmall(int i, Index&a, Index&b, Index&c, Index&d);
    void accumulateForceSmall( Vector& f, const Vector & p, Index elementIndex );
    void applyStiffnessSmall( Vector& f, const Vector& x, int i=0, Index a=0,Index b=1,Index c=2,Index d=3  );

    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, Index elementIndex );
    void applyStiffnessLarge( Vector& f, const Vector& x, int i=0, Index a=0,Index b=1,Index c=2,Index d=3 );

    void initPolar(int i, Index&a, Index&b, Index&c, Index&d);
    void accumulateForcePolar( Vector& f, const Vector & p,Index elementIndex );
    void applyStiffnessPolar( Vector& f, const Vector& x, int i=0, Index a=0,Index b=1,Index c=2,Index d=3  );

    static void CFTetrahedronCreationFunction (int , void* , 
                            TetrahedronInformation &,
                            const Tetrahedron& , const helper::vector< unsigned int > &, const helper::vector< double >&);



};

} // namespace forcefield

} // namespace component

} // namespace sofa

#endif