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EllipticalCylinderDemo

vtk-examples/Cxx/GeometricObjects/EllipticalCylinderDemo

Description

The example shows the vtkPolyLine that forms the base of the elliptical cylinder and an oriented arrow that represents the vector that vtkLinearExtrusionFilter uses to create the cylinder. The example takes an optional triple that defines the vector for the filter. The length of the vector is the height of the cylinder.

Other languages

See (Python)

Question

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

Code

EllipticalCylinderDemo.cxx

#include <vtkActor.h>
#include <vtkArrowSource.h>
#include <vtkCamera.h>
#include <vtkInteractorStyleTrackballCamera.h>
#include <vtkLinearExtrusionFilter.h>
#include <vtkMinimalStandardRandomSequence.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPoints.h>
#include <vtkPolyDataMapper.h>
#include <vtkPolyLine.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkTransform.h>
#include <vtkTransformPolyDataFilter.h>
#include <vtkTubeFilter.h>

int main(int argc, char* argv[])
{
  double nx = 0.0;
  double ny = 0.0;
  double nz = 100.0;

  if (argc > 3)
  {
    nx = atof(argv[1]);
    ny = atof(argv[2]);
    nz = atof(argv[3]);
  }
  vtkNew<vtkNamedColors> colors;

  double angle = 0;
  double r1, r2;
  double centerX, centerY;
  r1 = 50;
  r2 = 30;
  centerX = 10.0;
  centerY = 5.0;

  vtkNew<vtkPoints> points;
  int id = 0;
  while (angle <= 2.0 * vtkMath::Pi() + (vtkMath::Pi() / 60.0))
  {
    points->InsertNextPoint(r1 * cos(angle) + centerX,
                            r2 * sin(angle) + centerY, 0.0);
    angle = angle + (vtkMath::Pi() / 60.0);
    ++id;
  }

  vtkNew<vtkPolyLine> line;
  line->GetPointIds()->SetNumberOfIds(id);
  for (unsigned int i = 0; i < static_cast<unsigned int>(id); ++i)
  {
    line->GetPointIds()->SetId(i, i);
  }

  vtkNew<vtkCellArray> lines;
  lines->InsertNextCell(line);

  vtkNew<vtkPolyData> polyData;
  polyData->SetPoints(points);
  polyData->SetLines(lines);

  vtkNew<vtkLinearExtrusionFilter> extrude;
  extrude->SetInputData(polyData);
  extrude->SetExtrusionTypeToNormalExtrusion();
  extrude->SetVector(nx, ny, nz);
  extrude->Update();

  // Create an oriented arrow
  double startPoint[3], endPoint[3];
  startPoint[0] = centerX;
  startPoint[1] = centerY;
  startPoint[2] = 0.0;
  for (auto i = 0; i < 3; ++i)
  {
    endPoint[i] = startPoint[i] + extrude->GetVector()[i];
  }

  // Compute a basis
  double normalizedX[3];
  double normalizedY[3];
  double normalizedZ[3];

  // The X axis is a vector from start to end
  vtkMath::Subtract(endPoint, startPoint, normalizedX);
  double length = vtkMath::Norm(normalizedX);
  vtkMath::Normalize(normalizedX);

  vtkNew<vtkMinimalStandardRandomSequence> rng;
  rng->SetSeed(8775070);
  auto max_r = 10.0;

  // The Z axis is an arbitrary vector cross X
  double arbitrary[3];
  for (auto i = 0; i < 3; ++i)
  {
    arbitrary[i] = rng->GetRangeValue(-max_r, max_r);
    rng->Next();
  }
  vtkMath::Cross(normalizedX, arbitrary, normalizedZ);
  vtkMath::Normalize(normalizedZ);

  // The Y axis is Z cross X
  vtkMath::Cross(normalizedZ, normalizedX, normalizedY);
  vtkNew<vtkMatrix4x4> matrix;

  // Create the direction cosine matrix
  matrix->Identity();
  for (unsigned int i = 0; i < 3; i++)
  {
    matrix->SetElement(i, 0, normalizedX[i]);
    matrix->SetElement(i, 1, normalizedY[i]);
    matrix->SetElement(i, 2, normalizedZ[i]);
  }

  // Apply the transforms
  vtkNew<vtkTransform> transform;
  transform->Translate(startPoint);
  transform->Concatenate(matrix);
  transform->Scale(length, length, length);

  vtkNew<vtkArrowSource> arrowSource;
  arrowSource->SetTipResolution(31);
  arrowSource->SetShaftResolution(21);

  // Transform the polydata
  vtkNew<vtkTransformPolyDataFilter> transformPD;
  transformPD->SetTransform(transform);
  transformPD->SetInputConnection(arrowSource->GetOutputPort());

  // Create a mapper and actor for the arrow
  vtkNew<vtkPolyDataMapper> arrowMapper;
  arrowMapper->SetInputConnection(transformPD->GetOutputPort());

  vtkNew<vtkActor> arrowActor;
  arrowActor->SetMapper(arrowMapper);
  arrowActor->GetProperty()->SetColor(colors->GetColor3d("Tomato").GetData());

  vtkNew<vtkTubeFilter> tubes;
  tubes->SetInputData(polyData);
  tubes->SetRadius(2.0);
  tubes->SetNumberOfSides(21);

  vtkNew<vtkPolyDataMapper> lineMapper;
  lineMapper->SetInputConnection(tubes->GetOutputPort());

  vtkNew<vtkActor> lineActor;
  lineActor->SetMapper(lineMapper);
  lineActor->GetProperty()->SetColor(colors->GetColor3d("Peacock").GetData());

  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputConnection(extrude->GetOutputPort());

  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);
  actor->GetProperty()->SetColor(colors->GetColor3d("Banana").GetData());
  actor->GetProperty()->SetOpacity(.7);

  vtkNew<vtkRenderer> ren;
  ren->SetBackground(colors->GetColor3d("SlateGray").GetData());
  ren->AddActor(actor);
  ren->AddActor(lineActor);
  ren->AddActor(arrowActor);

  vtkNew<vtkRenderWindow> renWin;
  renWin->SetWindowName("EllipticalCylinderDemo");
  renWin->AddRenderer(ren);
  renWin->SetSize(600, 600);

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

  vtkNew<vtkInteractorStyleTrackballCamera> style;
  iren->SetInteractorStyle(style);

  vtkNew<vtkCamera> camera;
  camera->SetPosition(0, 1, 0);
  camera->SetFocalPoint(0, 0, 0);
  camera->SetViewUp(0, 0, 1);
  camera->Azimuth(30);
  camera->Elevation(30);

  ren->SetActiveCamera(camera);
  ren->ResetCamera();
  ren->ResetCameraClippingRange();

  renWin->Render();
  iren->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(EllipticalCylinderDemo)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkCommonTransforms
  vtkFiltersCore
  vtkFiltersGeneral
  vtkFiltersModeling
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping EllipticalCylinderDemo: ${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(EllipticalCylinderDemo MACOSX_BUNDLE EllipticalCylinderDemo.cxx )
  target_link_libraries(EllipticalCylinderDemo PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(EllipticalCylinderDemo MACOSX_BUNDLE EllipticalCylinderDemo.cxx )
  target_link_libraries(EllipticalCylinderDemo PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS EllipticalCylinderDemo
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build EllipticalCylinderDemo

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

cd EllipticalCylinderDemo/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:

./EllipticalCylinderDemo

WINDOWS USERS

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