text: /*=========================================================================
   *
   *  Copyright Insight Software Consortium
   *
   *  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.
   *
   *=========================================================================*/
  
  
  #include "itkFEMSolver.h"
  #include "itkFEMSpatialObjectReader.h"
  #include "itkFEMSpatialObjectWriter.h"
  
  int
  itkFEMElement2DC0LinearLineStressTest(int argc, char * argv[])
  {
    if (argc < 1)
    {
      std::cerr << "Missing Spatial Object Filename" << std::endl;
      return EXIT_FAILURE;
    }
    // Need to register default FEM object types,
    // and setup SpatialReader to recognize FEM types
    // which is all currently done as a HACK in
    // the initializaiton of the itk::FEMFactoryBase::GetFactory()
    itk::FEMFactoryBase::GetFactory()->RegisterDefaultTypes();
  
    using Solver2DType = itk::fem::Solver<2>;
    Solver2DType::Pointer solver = Solver2DType::New();
  
    using FEMSpatialObjectReaderType = itk::FEMSpatialObjectReader<2>;
    using FEMSpatialObjectReaderPointer = FEMSpatialObjectReaderType::Pointer;
    FEMSpatialObjectReaderPointer SpatialReader = FEMSpatialObjectReaderType::New();
    SpatialReader->SetFileName(argv[1]);
    //  SpatialReader->SetFileName("C:/Research/ITKGit/ITK/Testing/Data/Input/FEM/2DC0LinearLineStressTest.meta");
    SpatialReader->Update();
  
    FEMSpatialObjectReaderType::GroupPointer myGroup = SpatialReader->GetGroup();
    if (!myGroup)
    {
      std::cout << "No Group : [FAILED]" << std::endl;
      return EXIT_FAILURE;
    }
    std::cout << " [PASSED]" << std::endl;
  
    // Testing the fe mesh validity
    using FEMObjectSpatialObjectType = itk::FEMObjectSpatialObject<2>;
  
    FEMObjectSpatialObjectType::ChildrenListType * children = SpatialReader->GetGroup()->GetChildren();
    if (children->front()->GetTypeName() != "FEMObjectSpatialObject")
    {
      std::cout << " [FAILED]" << std::endl;
      return EXIT_FAILURE;
    }
  
    FEMObjectSpatialObjectType::Pointer femSO =
      dynamic_cast<FEMObjectSpatialObjectType *>((*(children->begin())).GetPointer());
    if (!femSO)
    {
      std::cout << " dynamic_cast [FAILED]" << std::endl;
      return EXIT_FAILURE;
    }
    delete children;
  
    femSO->GetFEMObject()->FinalizeMesh();
  
    solver->SetInput(femSO->GetFEMObject());
    solver->Update();
  
    int               numDOF = femSO->GetFEMObject()->GetNumberOfDegreesOfFreedom();
    vnl_vector<float> soln(numDOF);
    float             expectedResult[6] = { 0.0f, 0.0f, 1.66667e-07f, 0.0f, 5e-07f, 0.0f };
  
    bool foundError = false;
    for (int i = 0; i < numDOF; i++)
    {
      soln[i] = solver->GetSolution(i);
      if (std::fabs(expectedResult[i] - soln[i]) > 0.0000001)
      {
        std::cout << "ERROR: Index " << i << ". Expected " << expectedResult[i] << " Solution " << soln[i] << std::endl;
        foundError = true;
      }
    }
  
    if (foundError)
    {
      std::cout << "Test FAILED!" << std::endl;
      return EXIT_FAILURE;
    }
  
    // to write the deformed mesh
    FEMObjectSpatialObjectType::Pointer femSODef = FEMObjectSpatialObjectType::New();
    femSODef->SetFEMObject(solver->GetOutput());
    using FEMSpatialObjectWriterType = itk::FEMSpatialObjectWriter<2>;
    using FEMSpatialObjectWriterPointer = FEMSpatialObjectWriterType::Pointer;
    FEMSpatialObjectWriterPointer SpatialWriter = FEMSpatialObjectWriterType::New();
    SpatialWriter->SetInput(femSODef);
    //  SpatialWriter->SetFileName("C:/Research/ITKGit/ITK/Testing/Data/Input/FEM/2DC0LinearLineStressTestWrite.meta");
    SpatialWriter->SetFileName(argv[2]);
    SpatialWriter->Update();
  
    std::cout << "Test PASSED!" << std::endl;
    return EXIT_SUCCESS;
  }
  