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CellTypeSource

vtk-examples/Cxx/GeometricObjects/CellTypeSource


Description

This example uses vtkCellTypeSource to generate a vtkUnstructuredGrid. If a cell does not fill a rectangular area or volume, then multiple cells will be generated. For example, a vtkTetra requires 12 cells to fill a cube. A vtkTriangle requires two cells to fill a square. vtkCellTypeSource generates a uniform set of coordinates. The example perturbs those coordinates to illustrate the results of the vtkTessellatorFilter. Also, each cell is passed through vtkShrinkFilter to help identify the cells. Each generated cell also has a unique color.

The example takes an optional argument, a vtkCell name.

For example, to generate vtkTriangles, run

CellTypeSource [vtkTriangle](https://www.vtk.org/doc/nightly/html/classvtkTriangle.html#details)

Other languages

See (Python)

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

CellTypeSource.cxx

#include <vtkActor.h>
#include <vtkActor2D.h>
#include <vtkCamera.h>
#include <vtkCellData.h>
#include <vtkCellType.h>
#include <vtkCellTypeSource.h>
#include <vtkCellTypes.h>
#include <vtkColorSeries.h>
#include <vtkDataSetMapper.h>
#include <vtkIntArray.h>
#include <vtkLookupTable.h>
#include <vtkMath.h>
#include <vtkMinimalStandardRandomSequence.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkShrinkFilter.h>
#include <vtkTessellatorFilter.h>
#include <vtkTextMapper.h>
#include <vtkTextProperty.h>
#include <vtkUnstructuredGrid.h>

#include <map>

int main(int argc, char* argv[])
{
  std::string cellName = "vtkTetra";
  if (argc > 1)
  {
    cellName = std::string(argv[1]);
  }

  // Store cell class names in a map
  std::map<std::string, int> cellMap;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_LINE)] = VTK_LINE;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_QUADRATIC_EDGE)] =
      VTK_QUADRATIC_EDGE;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_CUBIC_LINE)] =
      VTK_CUBIC_LINE;

  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_TRIANGLE)] = VTK_TRIANGLE;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_QUADRATIC_TRIANGLE)] =
      VTK_QUADRATIC_TRIANGLE;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_QUAD)] = VTK_QUAD;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_QUADRATIC_QUAD)] =
      VTK_QUADRATIC_QUAD;

  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_TETRA)] = VTK_TETRA;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_HEXAHEDRON)] =
      VTK_HEXAHEDRON;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_WEDGE)] = VTK_WEDGE;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_PYRAMID)] = VTK_PYRAMID;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_QUADRATIC_WEDGE)] =
      VTK_QUADRATIC_WEDGE;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_QUADRATIC_PYRAMID)] =
      VTK_QUADRATIC_PYRAMID;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_QUADRATIC_HEXAHEDRON)] =
      VTK_QUADRATIC_HEXAHEDRON;
  cellMap[vtkCellTypes::GetClassNameFromTypeId(VTK_QUADRATIC_TETRA)] =
      VTK_QUADRATIC_TETRA;

  if (cellMap.find(std::string(cellName)) == cellMap.end())
  {
    std::cout << "Cell type " << cellName << " is not supported." << std::endl;
    return EXIT_FAILURE;
  }
  vtkNew<vtkCellTypeSource> source;
  source->SetCellType(cellMap[cellName]);
  source->Update();
  std::cout << "Cell: " << cellName << std::endl;

  vtkPoints* originalPoints = source->GetOutput()->GetPoints();
  vtkNew<vtkPoints> points;
  points->SetNumberOfPoints(source->GetOutput()->GetNumberOfPoints());
  vtkNew<vtkMinimalStandardRandomSequence> rng;
  rng->SetSeed(5070); // for testing
  for (auto i = 0; i < points->GetNumberOfPoints(); ++i)
  {
    double perturbation[3];
    for (auto j = 0; j < 3; ++j)
    {
      rng->Next();
      perturbation[j] = rng->GetRangeValue(-0.1, 0.1);
    }
    double currentPoint[3];
    originalPoints->GetPoint(i, currentPoint);
    points->SetPoint(i, currentPoint[0] + perturbation[0],
                     currentPoint[1] + perturbation[1],
                     currentPoint[2] + perturbation[2]);
  }
  source->GetOutput()->SetPoints(points);

  int numCells = source->GetOutput()->GetNumberOfCells();
  std::cout << "Number of cells: " << numCells << std::endl;
  vtkNew<vtkIntArray> idArray;
  idArray->SetNumberOfTuples(numCells);
  for (auto i = 0; i < numCells; ++i)
  {
    idArray->InsertTuple1(i, i + 1);
  }
  idArray->SetName("Ids");
  source->GetOutput()->GetCellData()->AddArray(idArray);
  source->GetOutput()->GetCellData()->SetActiveScalars("Ids");

  vtkNew<vtkShrinkFilter> shrink;
  shrink->SetInputConnection(source->GetOutputPort());
  shrink->SetShrinkFactor(.8);

  vtkNew<vtkTessellatorFilter> tessellate;
  tessellate->SetInputConnection(shrink->GetOutputPort());
  tessellate->SetMaximumNumberOfSubdivisions(3);

  // Create a lookup table to map cell data to colors
  vtkNew<vtkLookupTable> lut;

  vtkNew<vtkColorSeries> colorSeries;
  int seriesEnum = colorSeries->BREWER_QUALITATIVE_SET3;
  ;
  colorSeries->SetColorScheme(seriesEnum);
  colorSeries->BuildLookupTable(lut, colorSeries->ORDINAL);

  // Fill in a few known colors, the rest will be generated if needed
  vtkNew<vtkNamedColors> colors;

  // Create a mapper and actor
  vtkNew<vtkDataSetMapper> mapper;
  mapper->SetInputConnection(source->GetOutputPort());
  mapper->SetInputConnection(shrink->GetOutputPort());
  mapper->SetScalarRange(0, numCells + 1);
  mapper->SetLookupTable(lut);
  mapper->SetScalarModeToUseCellData();
  mapper->SetResolveCoincidentTopologyToPolygonOffset();
  if (source->GetCellType() == VTK_QUADRATIC_PYRAMID ||
      source->GetCellType() == VTK_QUADRATIC_WEDGE)
  {
    mapper->SetInputConnection(shrink->GetOutputPort());
  }
  else
  {
    mapper->SetInputConnection(tessellate->GetOutputPort());
  }
  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);
  actor->GetProperty()->EdgeVisibilityOn();
  //  actor->GetProperty()->SetLineWidth(3);

  vtkNew<vtkTextProperty> textProperty;
  textProperty->SetFontSize(20);
  textProperty->SetJustificationToCentered();
  textProperty->SetColor(colors->GetColor3d("Lamp_Black").GetData());

  vtkNew<vtkTextMapper> textMapper;
  textMapper->SetInput(cellName.c_str());
  textMapper->SetTextProperty(textProperty);

  vtkNew<vtkActor2D> textActor;
  textActor->SetMapper(textMapper);
  textActor->SetPosition(320, 20);

  // Create a renderer, render window, and interactor
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->SetWindowName("CellTypeSource");
  renderWindow->AddRenderer(renderer);
  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actors to the scene
  renderer->AddViewProp(textActor);
  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("Silver").GetData());

  renderer->ResetCamera();
  renderer->GetActiveCamera()->Azimuth(30);
  renderer->GetActiveCamera()->Elevation(30);
  renderer->ResetCameraClippingRange();

  // Render and interact
  renderWindow->SetSize(640, 480);
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(CellTypeSource)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersGeneral
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping CellTypeSource: ${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(CellTypeSource MACOSX_BUNDLE CellTypeSource.cxx )
  target_link_libraries(CellTypeSource PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(CellTypeSource MACOSX_BUNDLE CellTypeSource.cxx )
  target_link_libraries(CellTypeSource PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS CellTypeSource
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build CellTypeSource

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

cd CellTypeSource/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:

./CellTypeSource

WINDOWS USERS

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