SplitPolyData

VTKExamples/Cxx/Meshes/SplitPolyData

Description

The vtkOBBDicer filter breaks up an input mesh into a number of pieces. The resulting mesh contains scalar point data that can be used to extract the individual pieces with a filter like vtkThresholdFilter. This example stores each piece into a .vtp file.

Code

SplitPolyData.cxx

#include <vtkVersion.h>
#include <vtkSmartPointer.h>

#include <vtkOBBDicer.h>
#include <vtkSphereSource.h>
#include <vtkXMLPolyDataReader.h>
#include <vtkXMLPolyDataWriter.h>
#include <vtkThreshold.h>
#include <vtkGeometryFilter.h>

#include <vtksys/SystemTools.hxx>
#include <sstream>

int main(int argc, char *argv[])
{
  std::string filename;
  std::string extension;

  vtkSmartPointer<vtkPolyData> inputPolyData;
  if(argc > 1)
  {
    filename = vtksys::SystemTools::GetFilenameWithoutExtension(std::string(argv[1]));
    extension = vtksys::SystemTools::GetFilenameExtension(std::string(argv[1]));
    vtkSmartPointer<vtkXMLPolyDataReader> reader =
      vtkSmartPointer<vtkXMLPolyDataReader>::New();
    reader->SetFileName(argv[1]);
    reader->Update();
    inputPolyData = reader->GetOutput();
  }
  else
  {
    filename = "sphere";
    extension = ".vtp";
    vtkSmartPointer<vtkSphereSource> sphereSource =
      vtkSmartPointer<vtkSphereSource>::New();
    sphereSource->SetThetaResolution(30);
    sphereSource->SetPhiResolution(15);
    sphereSource->Update();
    inputPolyData = sphereSource->GetOutput();
  }

  // Create pipeline
  vtkSmartPointer<vtkOBBDicer> dicer =
  vtkSmartPointer<vtkOBBDicer>::New();
#if VTK_MAJOR_VERSION <= 5
  dicer->SetInput(inputPolyData);
#else
  dicer->SetInputData(inputPolyData);
#endif
  dicer->SetNumberOfPieces(4);
  dicer->SetDiceModeToSpecifiedNumberOfPieces();
  dicer->Update();

  vtkSmartPointer<vtkThreshold> selector =
    vtkSmartPointer<vtkThreshold>::New();
  selector->SetInputArrayToProcess(0, 0, 0, 0, "vtkOBBDicer_GroupIds");
  selector->SetInputConnection(dicer->GetOutputPort());
  selector->AllScalarsOff();
  vtkSmartPointer<vtkGeometryFilter> geometry =
    vtkSmartPointer<vtkGeometryFilter>::New();
  geometry->SetInputConnection(selector->GetOutputPort());

  vtkSmartPointer<vtkXMLPolyDataWriter> writer =
    vtkSmartPointer<vtkXMLPolyDataWriter>::New();
  writer->SetInputConnection(geometry->GetOutputPort());
  for (int i = 0; i < dicer->GetNumberOfActualPieces(); ++i)
  {
    std::stringstream pieceName;
    pieceName << filename << "_" << i + 1 << extension;
    selector->ThresholdBetween(i, i);
    writer->SetFileName(pieceName.str().c_str());
    writer->Write();
  }
  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(SplitPolyData)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(SplitPolyData MACOSX_BUNDLE SplitPolyData.cxx)

target_link_libraries(SplitPolyData ${VTK_LIBRARIES})

Download and Build SplitPolyData

Danger

The generation of tar files has not been ported to the new VTKExamples. Some tarballs may be missing or out-of-date.

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

cd SplitPolyData/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:

./SplitPolyData

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