VtkStripsToPolys.cpp

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///////////////////////////////////////////////////////////////////////////////
//
// File: VtkStripsToPolys.cpp
//
// For more information, please see: http://www.nektar.info
//
// The MIT License
//
// Copyright (c) 2006 Division of Applied Mathematics, Brown University (USA),
// Department of Aeronautics, Imperial College London (UK), and Scientific
// Computing and Imaging Institute, University of Utah (USA).
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
// Description:
//
///////////////////////////////////////////////////////////////////////////////
 
#include <LibUtilities/BasicUtils/SessionReader.h>
#include <LibUtilities/BasicUtils/VtkUtil.hpp>
 
#include <vtkCellArray.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataReader.h>
#include <vtkPolyDataWriter.h>
#include <vtkTriangle.h>
 
int main(int argc, char *argv[])
{
    if (argc < 2)
    {
        cout << "Usage: VtkStripsToPolys vtk-file" << endl;
        exit(-1);
    }
 
    vtkIdType npts;
#if VTK_MAJOR_VERSION >= 9 ||                                                  \
    (VTK_MAJOR_VERSION >= 8 && VTK_MINOR_VERSION >= 90)
    const vtkIdType *pts = nullptr;
#else
    vtkIdType *pts = 0;
#endif
 
    // Read mesh
    vtkPolyDataReader *vtkMeshReader = vtkPolyDataReader::New();
    vtkMeshReader->SetFileName(argv[1]);
    vtkMeshReader->Update();
    vtkPolyData *vtkMesh    = vtkMeshReader->GetOutput();
    vtkPoints *vtkPoints    = vtkMesh->GetPoints();
    vtkCellArray *vtkStrips = vtkMesh->GetStrips();
 
    // Check we found points and strips in the file.
    ASSERTL0(vtkPoints, "ERROR: cannot get points from mesh.");
    ASSERTL0(vtkStrips, "ERROR: cannot get triangle strips from mesh.");
 
    // Create new cell array for polygons
    vtkCellArray *vtkPolys = vtkCellArray::New();
 
    // Generate the polygons from the triangle strips
    vtkStrips->InitTraversal();
    while (vtkStrips->GetNextCell(npts, pts))
    {
        for (int j = 0; j < npts - 2; ++j)
        {
            vtkPolys->InsertNextCell(3, &pts[j]);
        }
    }
 
    // Create the new poly data
    vtkPolyData *vtkNewMesh = vtkPolyData::New();
    vtkNewMesh->SetPoints(vtkPoints);
    vtkNewMesh->SetPolys(vtkPolys);
 
    // Copy data across
    for (int i = 0; i < vtkMesh->GetPointData()->GetNumberOfArrays(); ++i)
    {
        vtkNewMesh->GetPointData()->SetScalars(
            vtkMesh->GetPointData()->GetArray(i));
    }
 
    // Write out the new mesh
    vtkPolyDataWriter *vtkMeshWriter = vtkPolyDataWriter::New();
    vtkMeshWriter->SetFileName(argv[2]);
#if VTK_MAJOR_VERSION <= 5
    vtkMeshWriter->SetInput(vtkNewMesh);
#else
    vtkMeshWriter->SetInputData(vtkNewMesh);
#endif
    vtkMeshWriter->Write();
}