/*=========================================================================

   Library: iMSTK

   Copyright (c) Kitware, Inc. & Center for Modeling, Simulation,
   & Imaging in Medicine, Rensselaer Polytechnic Institute.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0.txt

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

=========================================================================*/

#pragma once

#include "imstkPbdConstraint.h"

namespace imstk
{
///
/// \class PbdFEMConstraint
///
/// \brief The PbdFEMConstraint class for constraint as the elastic energy
/// computed by linear shape functions with tetrahedral mesh.
/// We provide several model for elastic energy including:
/// Linear, Co-rotation, St Venant-Kirchhof and NeoHookean
///
class PbdFEMConstraint : public PbdConstraint
{
public:
    // Material type
    enum class MaterialType
    {
        Linear,
        Corotation,
        StVK,
        NeoHookean
    };

    ///
    /// \brief Constructor
    ///
    explicit PbdFEMConstraint(const unsigned int cardinality, MaterialType mtype = MaterialType::StVK) :
        PbdConstraint(), m_material(mtype)
    {
        m_vertexIds.resize(cardinality);
    }

public:
    double m_elementVolume;     ///> Volume of the element
    MaterialType m_material;    ///> Material type
    Mat3d m_invRestMat;         ///>
};
}

