# Hexahedron

vtk-examples/Cxx/GeometricObjects/Hexahedron

### Description¶

The hexahedron is a primary three-dimensional cell consisting of six quadrilateral faces, twelve edges, and eight vertices. The hexahedron is defined by an ordered list of eight points. The faces and edges must not intersect any other faces and edges, and the hexahedron must be convex.

Other languages

See (Python), (CSharp)

Question

### Code¶

Hexahedron.cxx

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkCellArray.h>
#include <vtkDataSetMapper.h>
#include <vtkHexahedron.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPoints.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkUnstructuredGrid.h>

#include <array>
#include <vector>

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());

// For the hexahedron; setup the coordinates of eight points.
// The two faces must be in counter clockwise order as viewed from the
// outside.
std::vector<std::array<double, 3>> pointCoordinates;
pointCoordinates.push_back({{0.0, 0.0, 0.0}}); // Face 1
pointCoordinates.push_back({{1.0, 0.0, 0.0}});
pointCoordinates.push_back({{1.0, 1.0, 0.0}});
pointCoordinates.push_back({{0.0, 1.0, 0.0}});
pointCoordinates.push_back({{0.0, 0.0, 1.0}}); // Face 2
pointCoordinates.push_back({{1.0, 0.0, 1.0}});
pointCoordinates.push_back({{1.0, 1.0, 1.0}});
pointCoordinates.push_back({{0.0, 1.0, 1.0}});

// Create the points.
vtkNew<vtkPoints> points;

// Create a hexahedron from the points.
vtkNew<vtkHexahedron> hex;

for (auto i = 0; i < pointCoordinates.size(); ++i)
{
points->InsertNextPoint(pointCoordinates[i].data());
hex->GetPointIds()->SetId(i, i);
}

// Add the hexahedron to a cell array.
vtkNew<vtkCellArray> hexs;
hexs->InsertNextCell(hex);

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

// Visualize.
vtkNew<vtkDataSetMapper> mapper;
mapper->SetInputData(uGrid);

vtkNew<vtkActor> actor;
actor->GetProperty()->SetColor(colors->GetColor3d("PeachPuff").GetData());
actor->SetMapper(mapper);

vtkNew<vtkRenderer> renderer;
vtkNew<vtkRenderWindow> renderWindow;
renderWindow->SetWindowName("Hexahedron");
vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
renderWindowInteractor->SetRenderWindow(renderWindow);

renderer->SetBackground(colors->GetColor3d("BkgColor").GetData());
renderer->ResetCamera();
renderer->GetActiveCamera()->Azimuth(30);
renderer->GetActiveCamera()->Elevation(30);

renderWindow->Render();
renderWindowInteractor->Start();

return EXIT_SUCCESS;
}


### CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(Hexahedron)

find_package(VTK COMPONENTS
CommonColor
CommonCore
CommonDataModel
InteractionStyle
RenderingContextOpenGL2
RenderingCore
RenderingFreeType
RenderingGL2PSOpenGL2
RenderingOpenGL2
)

if (NOT VTK_FOUND)
message(FATAL_ERROR "Hexahedron: 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.")
target_link_libraries(Hexahedron PRIVATE ${VTK_LIBRARIES} ) # vtk_module_autoinit is needed vtk_module_autoinit( TARGETS Hexahedron MODULES${VTK_LIBRARIES}
)


cd Hexahedron/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:

./Hexahedron


WINDOWS USERS

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