# Cell3DDemonstration

VTKExamples/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

### 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 <vtkPentagonalPrism.h>
#include <vtkPoints.h>
#include <vtkPolyhedron.h>
#include <vtkProperty.h>
#include <vtkPyramid.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.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();
}

int main(int, char *[])
{
vtkSmartPointer<vtkNamedColors> colors =
vtkSmartPointer<vtkNamedColors>::New();

// 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");

vtkSmartPointer<vtkRenderWindow> renWin =
vtkSmartPointer<vtkRenderWindow>::New();
renWin->SetWindowName("Cell3D Demonstration");

vtkSmartPointer<vtkRenderWindowInteractor> iRen =
vtkSmartPointer<vtkRenderWindowInteractor>::New();
iRen->SetRenderWindow(renWin);

// Create one text property for all
vtkSmartPointer<vtkTextProperty> textProperty =
vtkSmartPointer<vtkTextProperty>::New();
textProperty->SetFontSize(16);
textProperty->SetJustificationToCentered();

// 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("Seashell").GetData());

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

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

}

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);
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->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;

vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();

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);

vtkSmartPointer<vtkHexagonalPrism> hexagonalPrism =
vtkSmartPointer<vtkHexagonalPrism>::New();
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
vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();
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
vtkSmartPointer<vtkHexahedron> hex =
vtkSmartPointer<vtkHexahedron>::New();
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
vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();
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
vtkSmartPointer<vtkPentagonalPrism> pentagonalPrism =
vtkSmartPointer<vtkPentagonalPrism>::New();
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;

vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();
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}
};

vtkSmartPointer<vtkCellArray> dodechedronFaces =
vtkSmartPointer<vtkCellArray>::New();
for (int i = 0; i < numberOfFaces; i++)
{
dodechedronFaces->InsertNextCell(numberOfFaceVertices, dodechedronFace[i]);
}

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

return uGrid;
}

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

vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();

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);

vtkSmartPointer<vtkPyramid> pyramid =
vtkSmartPointer<vtkPyramid>::New();
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;

vtkSmartPointer< vtkPoints > points =
vtkSmartPointer< vtkPoints > :: New();
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);
}

vtkSmartPointer<vtkCellArray> cellArray =
vtkSmartPointer<vtkCellArray>::New();
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;

vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();
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);

vtkSmartPointer<vtkVoxel> voxel =
vtkSmartPointer<vtkVoxel>::New();
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;

vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();

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);

vtkSmartPointer<vtkWedge> wedge =
vtkSmartPointer<vtkWedge>::New();
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;
}
}


### CMakeLists.txt¶

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(Cell3DDemonstration)

find_package(VTK COMPONENTS
vtkCommonColor
vtkCommonCore
vtkCommonDataModel
vtkInteractionStyle
vtkRenderingCore
vtkRenderingFreeType
vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
message("Skipping Cell3DDemonstration: ${VTK_NOT_FOUND_MESSAGE}") return () endif() message (STATUS "VTK_VERSION:${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
# old system
include(${VTK_USE_FILE}) add_executable(Cell3DDemonstration MACOSX_BUNDLE Cell3DDemonstration.cxx ) target_link_libraries(Cell3DDemonstration PRIVATE${VTK_LIBRARIES})
else ()
# include all components
target_link_libraries(Cell3DDemonstration PRIVATE ${VTK_LIBRARIES}) # vtk_module_autoinit is needed vtk_module_autoinit( TARGETS Cell3DDemonstration MODULES${VTK_LIBRARIES}
)
endif ()


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.