Hexahedron

VTKExamples/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)

Code

Hexahedron.cxx

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

#include <array>
#include <vector>

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());

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

  // Create a hexahedron from the points.
  vtkSmartPointer<vtkHexahedron> hex =
    vtkSmartPointer<vtkHexahedron>::New();

  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.
  vtkSmartPointer<vtkCellArray> hexs =
    vtkSmartPointer<vtkCellArray>::New();
  hexs->InsertNextCell(hex);

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

  // Visualize.
  vtkSmartPointer<vtkDataSetMapper> mapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  mapper->SetInputData(uGrid);

  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->GetProperty()->SetColor(colors->GetColor3d("Cornsilk").GetData());
  actor->SetMapper(mapper);

  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->SetWindowName("Hexahedron");
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  renderer->AddActor(actor);
  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 3.3 FATAL_ERROR)

project(Hexahedron)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkInteractionStyle
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping Hexahedron: ${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(Hexahedron MACOSX_BUNDLE Hexahedron.cxx )
  target_link_libraries(Hexahedron PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(Hexahedron MACOSX_BUNDLE Hexahedron.cxx )
  target_link_libraries(Hexahedron PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS Hexahedron
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build Hexahedron

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

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.