CellTypeSource

VTKExamples/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 optonal argument, a vtkCell name.

For example, to generate vtkTriangles, run

CellTypeSource vtkTriangle

Code

CellTypeSource.cxx

#include <vtkActor.h>
#include <vtkActor2D.h>
#include <vtkCamera.h>
#include <vtkCellData.h>
#include <vtkCellType.h>
#include <vtkCellTypes.h>
#include <vtkCellTypeSource.h>
#include <vtkColorSeries.h>
#include <vtkDataSetMapper.h>
#include <vtkIntArray.h>
#include <vtkLookupTable.h>
#include <vtkMath.h>
#include <vtkMinimalStandardRandomSequence.h>
#include <vtkNamedColors.h>
#include <vtkProperty.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkShrinkFilter.h>
#include <vtkSmartPointer.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[std::string(cellName)] == 0)
    {
      std::cout << "Cell type " << cellName << " is not supported." << std::endl;
      return EXIT_FAILURE;
    }
  vtkSmartPointer<vtkCellTypeSource> source =
    vtkSmartPointer<vtkCellTypeSource>::New();
  source->SetCellType(cellMap[cellName]);
  source->Update();
  std::cout << "Cell: "
            << cellName << std::endl;

  vtkPoints *originalPoints = source->GetOutput()->GetPoints();
  vtkSmartPointer<vtkPoints> points =
    vtkSmartPointer<vtkPoints>::New();
  points->SetNumberOfPoints(source->GetOutput()->GetNumberOfPoints());
  vtkSmartPointer<vtkMinimalStandardRandomSequence> rng =
    vtkSmartPointer<vtkMinimalStandardRandomSequence>::New();
  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;
  vtkSmartPointer<vtkIntArray> idArray =
    vtkSmartPointer<vtkIntArray>::New();
  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");

  vtkSmartPointer<vtkShrinkFilter> shrink =
    vtkSmartPointer<vtkShrinkFilter>::New();
  shrink->SetInputConnection(source->GetOutputPort());
  shrink->SetShrinkFactor(.8);

  vtkSmartPointer<vtkTessellatorFilter> tessellate =
    vtkSmartPointer<vtkTessellatorFilter>::New();
  tessellate->SetInputConnection(shrink->GetOutputPort());
  tessellate->SetMaximumNumberOfSubdivisions(3);

  // Create a lookup table to map cell data to colors
  vtkSmartPointer<vtkNamedColors> namedColors =
    vtkSmartPointer<vtkNamedColors>::New();

  vtkSmartPointer<vtkLookupTable> lut =
    vtkSmartPointer<vtkLookupTable>::New();

  vtkSmartPointer<vtkColorSeries> colorSeries =
    vtkSmartPointer<vtkColorSeries>::New();
  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
  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  //Create a mapper and actor
  vtkSmartPointer<vtkDataSetMapper> mapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  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());
  }
  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
  actor->GetProperty()->EdgeVisibilityOn();
//  actor->GetProperty()->SetLineWidth(3);

  vtkSmartPointer<vtkTextProperty> textProperty =
    vtkSmartPointer<vtkTextProperty>::New();
  textProperty->SetFontSize(20);
  textProperty->SetJustificationToCentered();
  textProperty->SetColor(colors->GetColor3d("Lamp_Black").GetData());

  vtkSmartPointer<vtkTextMapper> textMapper =
    vtkSmartPointer<vtkTextMapper>::New();
  textMapper->SetInput(cellName.c_str());
  textMapper->SetTextProperty(textProperty);

  vtkSmartPointer<vtkActor2D> textActor =
    vtkSmartPointer<vtkActor2D>::New();
  textActor->SetMapper(textMapper);
  textActor->SetPosition(320, 20);

  //Create a renderer, render window, and interactor
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->SetWindowName("Cell Type Source");
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  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 2.8)

PROJECT(CellTypeSource)

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

add_executable(CellTypeSource MACOSX_BUNDLE CellTypeSource.cxx )

target_link_libraries(CellTypeSource ${VTK_LIBRARIES})

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.