Skip to content

Cell3DDemonstration

vtk-examples/Cxx/GeometricObjects/Cell3DDemonstration

Description

This is a demonstration of how to construct and display geometric objects using the classes derived from vtkCell3D. For each object we specify the points and cell Ids.

From this we create an unstructured grid. In some cases a vtkCellArray is used and the result is added to the unstructured grid, see: MakePolyhedron() and MakeTetrahedron().

Also demonstrated is the use of vectors to hold the unstructured grids, mappers, actors and renderers.

The resultant objects are then displayed in a grid.

Other languages

See (Python)

Question

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

Code

Cell3DDemonstration.cxx

#include <vtkActor.h>
#include <vtkActor2D.h>
#include <vtkCamera.h>
#include <vtkCellArray.h>
#include <vtkDataSetMapper.h>
#include <vtkHexagonalPrism.h>
#include <vtkHexahedron.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPentagonalPrism.h>
#include <vtkPoints.h>
#include <vtkProperty.h>
#include <vtkPyramid.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkTetra.h>
#include <vtkTextMapper.h>
#include <vtkTextProperty.h>
#include <vtkUnstructuredGrid.h>
#include <vtkVoxel.h>
#include <vtkWedge.h>

#include <array>
#include <cstdlib>
#include <string>
#include <vector>

namespace {
// These functions return a vtkUnstructured grid corresponding to the object.
vtkSmartPointer<vtkUnstructuredGrid> MakeHexagonalPrism();
vtkSmartPointer<vtkUnstructuredGrid> MakeHexahedron();
vtkSmartPointer<vtkUnstructuredGrid> MakePentagonalPrism();

vtkSmartPointer<vtkUnstructuredGrid> MakePolyhedron();
vtkSmartPointer<vtkUnstructuredGrid> MakePyramid();
vtkSmartPointer<vtkUnstructuredGrid> MakeTetrahedron();

vtkSmartPointer<vtkUnstructuredGrid> MakeVoxel();
vtkSmartPointer<vtkUnstructuredGrid> MakeWedge();
} // namespace

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  // Set the background color.
  std::array<unsigned char, 4> bkg{{51, 77, 102, 255}};
  colors->SetColor("BkgColor", bkg.data());

  std::vector<std::string> titles;
  std::vector<vtkSmartPointer<vtkTextMapper>> textMappers;
  std::vector<vtkSmartPointer<vtkActor2D>> textActors;

  std::vector<vtkSmartPointer<vtkUnstructuredGrid>> uGrids;
  std::vector<vtkSmartPointer<vtkDataSetMapper>> mappers;
  std::vector<vtkSmartPointer<vtkActor>> actors;
  std::vector<vtkSmartPointer<vtkRenderer>> renderers;

  uGrids.push_back(MakeHexagonalPrism());
  titles.push_back("Hexagonal Prism");
  uGrids.push_back(MakeHexahedron());
  titles.push_back("Hexahedron");
  uGrids.push_back(MakePentagonalPrism());
  titles.push_back("Pentagonal Prism");

  uGrids.push_back(MakePolyhedron());
  titles.push_back("Polyhedron");
  uGrids.push_back(MakePyramid());
  titles.push_back("Pyramid");
  uGrids.push_back(MakeTetrahedron());
  titles.push_back("Tetrahedron");

  uGrids.push_back(MakeVoxel());
  titles.push_back("Voxel");
  uGrids.push_back(MakeWedge());
  titles.push_back("Wedge");

  vtkNew<vtkRenderWindow> renWin;
  renWin->SetWindowName("Cell3D Demonstration");

  vtkNew<vtkRenderWindowInteractor> iRen;
  iRen->SetRenderWindow(renWin);

  // Create one text property for all
  vtkNew<vtkTextProperty> textProperty;
  textProperty->SetFontSize(16);
  textProperty->SetJustificationToCentered();
  textProperty->SetColor(colors->GetColor3d("LightGoldenrodYellow").GetData());

  // Create and link the mappers actors and renderers together.
  for (unsigned int i = 0; i < uGrids.size(); ++i)
  {
    textMappers.push_back(vtkSmartPointer<vtkTextMapper>::New());
    textActors.push_back(vtkSmartPointer<vtkActor2D>::New());

    mappers.push_back(vtkSmartPointer<vtkDataSetMapper>::New());
    actors.push_back(vtkSmartPointer<vtkActor>::New());
    renderers.push_back(vtkSmartPointer<vtkRenderer>::New());
    mappers[i]->SetInputData(uGrids[i]);

    actors[i]->SetMapper(mappers[i]);
    actors[i]->GetProperty()->SetColor(
        colors->GetColor3d("PeachPuff").GetData());

    renderers[i]->AddViewProp(actors[i]);

    textMappers[i]->SetInput(titles[i].c_str());
    textMappers[i]->SetTextProperty(textProperty);

    textActors[i]->SetMapper(textMappers[i]);
    textActors[i]->SetPosition(120, 16);
    renderers[i]->AddViewProp(textActors[i]);

    renWin->AddRenderer(renderers[i]);
  }

  int gridDimensions = 3;
  int rendererSize = 300;

  renWin->SetSize(rendererSize * gridDimensions, rendererSize * gridDimensions);

  for (int row = 0; row < gridDimensions; row++)
  {
    for (int col = 0; col < gridDimensions; col++)
    {
      int index = row * gridDimensions + col;

      // (xmin, ymin, xmax, ymax)
      double viewport[4] = {static_cast<double>(col) * rendererSize /
                                (gridDimensions * rendererSize),
                            static_cast<double>(gridDimensions - (row + 1)) *
                                rendererSize / (gridDimensions * rendererSize),
                            static_cast<double>(col + 1) * rendererSize /
                                (gridDimensions * rendererSize),
                            static_cast<double>(gridDimensions - row) *
                                rendererSize / (gridDimensions * rendererSize)};

      if (index > int(actors.size()) - 1)
      {
        // Add a renderer even if there is no actor.
        // This makes the render window background all the same color.
        vtkSmartPointer<vtkRenderer> ren = vtkSmartPointer<vtkRenderer>::New();
        ren->SetBackground(colors->GetColor3d("BkgColor").GetData());
        ren->SetViewport(viewport);
        renWin->AddRenderer(ren);
        continue;
      }

      renderers[index]->SetViewport(viewport);
      renderers[index]->SetBackground(colors->GetColor3d("BkgColor").GetData());
      renderers[index]->ResetCamera();
      renderers[index]->GetActiveCamera()->Azimuth(30);
      renderers[index]->GetActiveCamera()->Elevation(-30);
      renderers[index]->GetActiveCamera()->Zoom(0.85);
      renderers[index]->ResetCameraClippingRange();
    }
  }

  iRen->Initialize();

  renWin->SetWindowName("Cell3DDemonstration");
  renWin->Render();

  iRen->Start();

  return EXIT_SUCCESS;
}

namespace {
vtkSmartPointer<vtkUnstructuredGrid> MakeHexagonalPrism()
{
  // 3D: hexagonal prism: a wedge with an hexagonal base.
  // Be careful, the base face ordering is different from wedge.

  int numberOfVertices = 12;

  vtkNew<vtkPoints> points;

  points->InsertNextPoint(0.0, 0.0, 1.0);
  points->InsertNextPoint(1.0, 0.0, 1.0);
  points->InsertNextPoint(1.5, 0.5, 1.0);
  points->InsertNextPoint(1.0, 1.0, 1.0);
  points->InsertNextPoint(0.0, 1.0, 1.0);
  points->InsertNextPoint(-0.5, 0.5, 1.0);

  points->InsertNextPoint(0.0, 0.0, 0.0);
  points->InsertNextPoint(1.0, 0.0, 0.0);
  points->InsertNextPoint(1.5, 0.5, 0.0);
  points->InsertNextPoint(1.0, 1.0, 0.0);
  points->InsertNextPoint(0.0, 1.0, 0.0);
  points->InsertNextPoint(-0.5, 0.5, 0.0);

  vtkNew<vtkHexagonalPrism> hexagonalPrism;
  for (int i = 0; i < numberOfVertices; ++i)
  {
    hexagonalPrism->GetPointIds()->SetId(i, i);
  }

  vtkSmartPointer<vtkUnstructuredGrid> ug =
      vtkSmartPointer<vtkUnstructuredGrid>::New();
  ug->InsertNextCell(hexagonalPrism->GetCellType(),
                     hexagonalPrism->GetPointIds());
  ug->SetPoints(points);

  return ug;
}

vtkSmartPointer<vtkUnstructuredGrid> MakeHexahedron()
{
  // A regular hexagon (cube) with all faces square and three squares around
  // each vertex is created below.

  // Setup the coordinates of eight points
  // (the two faces must be in counter clockwise
  // order as viewed from the outside).

  // As an exercise you can modify the coordinates of the points to create
  // seven topologically distinct convex hexahedras.

  int numberOfVertices = 8;

  // Create the points
  vtkNew<vtkPoints> points;
  points->InsertNextPoint(0.0, 0.0, 0.0);
  points->InsertNextPoint(1.0, 0.0, 0.0);
  points->InsertNextPoint(1.0, 1.0, 0.0);
  points->InsertNextPoint(0.0, 1.0, 0.0);
  points->InsertNextPoint(0.0, 0.0, 1.0);
  points->InsertNextPoint(1.0, 0.0, 1.0);
  points->InsertNextPoint(1.0, 1.0, 1.0);
  points->InsertNextPoint(0.0, 1.0, 1.0);

  // Create a hexahedron from the points
  vtkNew<vtkHexahedron> hex;
  for (int i = 0; i < numberOfVertices; ++i)
  {
    hex->GetPointIds()->SetId(i, i);
  }

  // Add the points and hexahedron to an unstructured grid
  vtkSmartPointer<vtkUnstructuredGrid> uGrid =
      vtkSmartPointer<vtkUnstructuredGrid>::New();
  uGrid->SetPoints(points);
  uGrid->InsertNextCell(hex->GetCellType(), hex->GetPointIds());

  return uGrid;
}

vtkSmartPointer<vtkUnstructuredGrid> MakePentagonalPrism()
{

  int numberOfVertices = 10;

  // Create the points
  vtkNew<vtkPoints> points;
  points->InsertNextPoint(11, 10, 10);
  points->InsertNextPoint(13, 10, 10);
  points->InsertNextPoint(14, 12, 10);
  points->InsertNextPoint(12, 14, 10);
  points->InsertNextPoint(10, 12, 10);
  points->InsertNextPoint(11, 10, 14);
  points->InsertNextPoint(13, 10, 14);
  points->InsertNextPoint(14, 12, 14);
  points->InsertNextPoint(12, 14, 14);
  points->InsertNextPoint(10, 12, 14);

  // Pentagonal Prism
  vtkNew<vtkPentagonalPrism> pentagonalPrism;
  for (int i = 0; i < numberOfVertices; ++i)
  {
    pentagonalPrism->GetPointIds()->SetId(i, i);
  }

  // Add the points and hexahedron to an unstructured grid
  vtkSmartPointer<vtkUnstructuredGrid> uGrid =
      vtkSmartPointer<vtkUnstructuredGrid>::New();
  uGrid->SetPoints(points);
  uGrid->InsertNextCell(pentagonalPrism->GetCellType(),
                        pentagonalPrism->GetPointIds());

  return uGrid;
}

vtkSmartPointer<vtkUnstructuredGrid> MakePolyhedron()
{

  // Make a regular dodecahedron. It consists of twelve regular pentagonal
  // faces with three faces meeting at each vertex.
  int numberOfVertices = 20;
  int numberOfFaces = 12;
  int numberOfFaceVertices = 5;

  vtkNew<vtkPoints> points;
  points->InsertNextPoint(1.21412, 0, 1.58931);
  points->InsertNextPoint(0.375185, 1.1547, 1.58931);
  points->InsertNextPoint(-0.982247, 0.713644, 1.58931);
  points->InsertNextPoint(-0.982247, -0.713644, 1.58931);
  points->InsertNextPoint(0.375185, -1.1547, 1.58931);
  points->InsertNextPoint(1.96449, 0, 0.375185);
  points->InsertNextPoint(0.607062, 1.86835, 0.375185);
  points->InsertNextPoint(-1.58931, 1.1547, 0.375185);
  points->InsertNextPoint(-1.58931, -1.1547, 0.375185);
  points->InsertNextPoint(0.607062, -1.86835, 0.375185);
  points->InsertNextPoint(1.58931, 1.1547, -0.375185);
  points->InsertNextPoint(-0.607062, 1.86835, -0.375185);
  points->InsertNextPoint(-1.96449, 0, -0.375185);
  points->InsertNextPoint(-0.607062, -1.86835, -0.375185);
  points->InsertNextPoint(1.58931, -1.1547, -0.375185);
  points->InsertNextPoint(0.982247, 0.713644, -1.58931);
  points->InsertNextPoint(-0.375185, 1.1547, -1.58931);
  points->InsertNextPoint(-1.21412, 0, -1.58931);
  points->InsertNextPoint(-0.375185, -1.1547, -1.58931);
  points->InsertNextPoint(0.982247, -0.713644, -1.58931);

  vtkIdType dodechedronPointsIds[20] = {0,  1,  2,  3,  4,  5,  6,  7,  8,  9,
                                        10, 11, 12, 13, 14, 15, 16, 17, 18, 19};

  vtkIdType dodechedronFace[12][5] = {
      {0, 1, 2, 3, 4},     {0, 5, 10, 6, 1},    {1, 6, 11, 7, 2},
      {2, 7, 12, 8, 3},    {3, 8, 13, 9, 4},    {4, 9, 14, 5, 0},
      {15, 10, 5, 14, 19}, {16, 11, 6, 10, 15}, {17, 12, 7, 11, 16},
      {18, 13, 8, 12, 17}, {19, 14, 9, 13, 18}, {19, 18, 17, 16, 15}};

  vtkNew<vtkIdList> dodechedronFaces;
  for (int i = 0; i < numberOfFaces; i++)
  {
    dodechedronFaces->InsertNextId(numberOfFaceVertices);
    for (int j = 0; j < numberOfFaceVertices; ++j)
    {
      dodechedronFaces->InsertNextId(dodechedronFace[i][j]);
    }
  }

  vtkSmartPointer<vtkUnstructuredGrid> uGrid =
      vtkSmartPointer<vtkUnstructuredGrid>::New();
  uGrid->InsertNextCell(VTK_POLYHEDRON, numberOfVertices, dodechedronPointsIds,
                        numberOfFaces, dodechedronFaces->GetPointer(0));
  uGrid->SetPoints(points);

  return uGrid;
}

vtkSmartPointer<vtkUnstructuredGrid> MakePyramid()
{
  // Make a regular square pyramid.
  int numberOfVertices = 5;

  vtkNew<vtkPoints> points;
  float p0[3] = {1.0, 1.0, 0.0};
  float p1[3] = {-1.0, 1.0, 0.0};
  float p2[3] = {-1.0, -1.0, 0.0};
  float p3[3] = {1.0, -1.0, 0.0};
  float p4[3] = {0.0, 0.0, 1.0};

  points->InsertNextPoint(p0);
  points->InsertNextPoint(p1);
  points->InsertNextPoint(p2);
  points->InsertNextPoint(p3);
  points->InsertNextPoint(p4);

  vtkNew<vtkPyramid> pyramid;
  for (int i = 0; i < numberOfVertices; ++i)
  {
    pyramid->GetPointIds()->SetId(i, i);
  }

  vtkSmartPointer<vtkUnstructuredGrid> ug =
      vtkSmartPointer<vtkUnstructuredGrid>::New();
  ug->SetPoints(points);
  ug->InsertNextCell(pyramid->GetCellType(), pyramid->GetPointIds());

  return ug;
}

vtkSmartPointer<vtkUnstructuredGrid> MakeTetrahedron()
{
  // Make a tetrahedron.
  int numberOfVertices = 4;

  vtkNew<vtkPoints> points;
  points->InsertNextPoint(0, 0, 0);
  points->InsertNextPoint(1, 0, 0);
  points->InsertNextPoint(1, 1, 0);
  points->InsertNextPoint(0, 1, 1);

  vtkSmartPointer<vtkTetra> tetra = vtkSmartPointer<vtkTetra>::New();
  for (int i = 0; i < numberOfVertices; ++i)
  {
    tetra->GetPointIds()->SetId(i, i);
  }

  vtkNew<vtkCellArray> cellArray;
  cellArray->InsertNextCell(tetra);

  vtkSmartPointer<vtkUnstructuredGrid> unstructuredGrid =
      vtkSmartPointer<vtkUnstructuredGrid>::New();
  unstructuredGrid->SetPoints(points);
  unstructuredGrid->SetCells(VTK_TETRA, cellArray);

  return unstructuredGrid;
}

vtkSmartPointer<vtkUnstructuredGrid> MakeVoxel()
{
  // A voxel is a representation of a regular grid in 3-D space.
  int numberOfVertices = 8;

  vtkNew<vtkPoints> points;
  points->InsertNextPoint(0, 0, 0);
  points->InsertNextPoint(1, 0, 0);
  points->InsertNextPoint(0, 1, 0);
  points->InsertNextPoint(1, 1, 0);
  points->InsertNextPoint(0, 0, 1);
  points->InsertNextPoint(1, 0, 1);
  points->InsertNextPoint(0, 1, 1);
  points->InsertNextPoint(1, 1, 1);

  vtkNew<vtkVoxel> voxel;
  for (int i = 0; i < numberOfVertices; ++i)
  {
    voxel->GetPointIds()->SetId(i, i);
  }

  vtkSmartPointer<vtkUnstructuredGrid> ug =
      vtkSmartPointer<vtkUnstructuredGrid>::New();
  ug->SetPoints(points);
  ug->InsertNextCell(voxel->GetCellType(), voxel->GetPointIds());

  return ug;
}

vtkSmartPointer<vtkUnstructuredGrid> MakeWedge()
{

  // A wedge consists of two triangular ends and three rectangular faces.

  int numberOfVertices = 6;

  vtkNew<vtkPoints> points;
  points->InsertNextPoint(0, 1, 0);
  points->InsertNextPoint(0, 0, 0);
  points->InsertNextPoint(0, .5, .5);
  points->InsertNextPoint(1, 1, 0);
  points->InsertNextPoint(1, 0.0, 0.0);
  points->InsertNextPoint(1, .5, .5);

  vtkNew<vtkWedge> wedge;
  for (int i = 0; i < numberOfVertices; ++i)
  {
    wedge->GetPointIds()->SetId(i, i);
  }

  vtkSmartPointer<vtkUnstructuredGrid> ug =
      vtkSmartPointer<vtkUnstructuredGrid>::New();
  ug->SetPoints(points);
  ug->InsertNextCell(wedge->GetCellType(), wedge->GetPointIds());

  return ug;
}
} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(Cell3DDemonstration)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "Cell3DDemonstration: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(Cell3DDemonstration MACOSX_BUNDLE Cell3DDemonstration.cxx )
  target_link_libraries(Cell3DDemonstration PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS Cell3DDemonstration
  MODULES ${VTK_LIBRARIES}
)

Download and Build Cell3DDemonstration

Click here to download Cell3DDemonstration and its CMakeLists.txt file. Once the tarball Cell3DDemonstration.tar has been downloaded and extracted,

cd Cell3DDemonstration/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:

./Cell3DDemonstration

WINDOWS USERS

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