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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 3.12 FATAL_ERROR)

project(EllipticalCylinderDemo)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  CommonDataModel
  CommonTransforms
  FiltersCore
  FiltersGeneral
  FiltersModeling
  FiltersSources
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "EllipticalCylinderDemo: 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(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}
)

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.