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PolyDataToUnstructuredGrid

vtk-examples/Cxx/PolyData/PolyDataToUnstructuredGrid

Description

There is not a filter whose sole purpose is converting a vtkPolyData to a vtkUnstructuredGrid. However, the append filter can accept any type of input, and produces a vtkUnstructuredGrid, so we can use it for this purpose.

Question

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Code

PolyDataToUnstructuredGrid.cxx

#include <vtkAppendFilter.h>
#include <vtkNew.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <vtkUnstructuredGrid.h>
#include <vtkXMLUnstructuredGridWriter.h>

int main(int, char*[])
{
  // Create a sphere
  vtkNew<vtkSphereSource> sphereSource;
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(5.0);
  sphereSource->Update();

  // Combine the two data sets
  vtkNew<vtkAppendFilter> appendFilter;
  appendFilter->AddInputData(sphereSource->GetOutput());
  appendFilter->Update();

  vtkNew<vtkUnstructuredGrid> unstructuredGrid;
  unstructuredGrid->ShallowCopy(appendFilter->GetOutput());

  // Write the unstructured grid
  vtkNew<vtkXMLUnstructuredGridWriter> writer;
  writer->SetFileName("UnstructuredGrid.vtu");
  writer->SetInputData(unstructuredGrid);
  writer->Write();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(PolyDataToUnstructuredGrid)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersCore
  vtkFiltersSources
  vtkIOXML
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping PolyDataToUnstructuredGrid: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(PolyDataToUnstructuredGrid MACOSX_BUNDLE PolyDataToUnstructuredGrid.cxx )
  target_link_libraries(PolyDataToUnstructuredGrid PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(PolyDataToUnstructuredGrid MACOSX_BUNDLE PolyDataToUnstructuredGrid.cxx )
  target_link_libraries(PolyDataToUnstructuredGrid PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS PolyDataToUnstructuredGrid
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build PolyDataToUnstructuredGrid

Click here to download PolyDataToUnstructuredGrid and its CMakeLists.txt file. Once the tarball PolyDataToUnstructuredGrid.tar has been downloaded and extracted,

cd PolyDataToUnstructuredGrid/build

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./PolyDataToUnstructuredGrid

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.