# EllipticalCylinderDemo

VTKExamples/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 simple question about this example contact us at VTKExamplesProject If your question is more complex and may require extended discussion, 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 <vtkNamedColors.h>
#include <vtkPoints.h>
#include <vtkPolyDataMapper.h>
#include <vtkPolyLine.h>
#include <vtkProperty.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.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]);
}
vtkSmartPointer<vtkNamedColors> colors =
vtkSmartPointer<vtkNamedColors>::New();

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

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

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

vtkSmartPointer<vtkCellArray> lines =
vtkSmartPointer<vtkCellArray>::New();
lines->InsertNextCell(line);

vtkSmartPointer<vtkPolyData> polyData =
vtkSmartPointer<vtkPolyData>::New();
polyData->SetPoints(points);
polyData->SetLines(lines);

vtkSmartPointer<vtkLinearExtrusionFilter> extrude =
vtkSmartPointer<vtkLinearExtrusionFilter>::New();
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;
endPoint[0] = startPoint[0] + extrude->GetVector()[0];
endPoint[1] = startPoint[1] + extrude->GetVector()[1];
endPoint[2] = startPoint[2] + extrude->GetVector()[2];

// 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);

// The Z axis is an arbitrary vector cross X
double arbitrary[3];
arbitrary[0] = vtkMath::Random(-10,10);
arbitrary[1] = vtkMath::Random(-10,10);
arbitrary[2] = vtkMath::Random(-10,10);
vtkMath::Cross(normalizedX, arbitrary, normalizedZ);
vtkMath::Normalize(normalizedZ);

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

// 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
vtkSmartPointer<vtkTransform> transform =
vtkSmartPointer<vtkTransform>::New();
transform->Translate(startPoint);
transform->Concatenate(matrix);
transform->Scale(length, length, length);

vtkSmartPointer<vtkArrowSource> arrowSource =
vtkSmartPointer<vtkArrowSource>::New();
arrowSource->SetTipResolution(31);
arrowSource->SetShaftResolution(21);

// Transform the polydata
vtkSmartPointer<vtkTransformPolyDataFilter> transformPD =
vtkSmartPointer<vtkTransformPolyDataFilter>::New();
transformPD->SetTransform(transform);
transformPD->SetInputConnection(arrowSource->GetOutputPort());

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

vtkSmartPointer<vtkActor> arrowActor =
vtkSmartPointer<vtkActor>::New();
arrowActor->SetMapper(arrowMapper);
arrowActor->GetProperty()->SetColor(colors->GetColor3d("Tomato").GetData());

vtkSmartPointer<vtkTubeFilter> tubes =
vtkSmartPointer<vtkTubeFilter>::New();
tubes->SetInputData(polyData);
tubes->SetNumberOfSides(21);

vtkSmartPointer<vtkPolyDataMapper> lineMapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
lineMapper->SetInputConnection(tubes->GetOutputPort());

vtkSmartPointer<vtkActor> lineActor =
vtkSmartPointer<vtkActor>::New();
lineActor->SetMapper(lineMapper);
lineActor->GetProperty()->SetColor(colors->GetColor3d("Peacock").GetData());

vtkSmartPointer<vtkPolyDataMapper> mapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
mapper->SetInputConnection(extrude->GetOutputPort());

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

vtkSmartPointer<vtkRenderer> ren =
vtkSmartPointer<vtkRenderer>::New();
ren->SetBackground(colors->GetColor3d("SlateGray").GetData());

vtkSmartPointer<vtkRenderWindow> renWin =
vtkSmartPointer<vtkRenderWindow>::New();
renWin->SetWindowName("Elliptical Cylinder Demo");
renWin->SetSize(600, 600);

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

vtkSmartPointer<vtkInteractorStyleTrackballCamera> style =
vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New();
iren->SetInteractorStyle(style);

vtkSmartPointer<vtkCamera> camera =
vtkSmartPointer<vtkCamera>::New();
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
vtkInteractionStyle
vtkRenderingCore
vtkRenderingFreeType
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 ()


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.