< VTK‎ | Examples‎ | Cxx

This example shows how to vary the radius of a tube with one scalar and color the tube with another.

• Contributed by Marcus Thamson

#include <math.h>

#include <vtkVersion.h>
#include <vtkPolyData.h>
#include <vtkPoints.h>
#include <vtkCellArray.h>
#include <vtkDoubleArray.h>
#include <vtkPolyData.h>
#include <vtkPointData.h>

#include <vtkCell.h>
#include <vtkCellData.h>
#include <vtkDataSet.h>
#include <vtkDataSetAttributes.h>
#include <vtkProperty.h>
#include <vtkSmartPointer.h>
#include <vtkTubeFilter.h>

#include <vtkDataSetMapper.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkCamera.h>
#include <vtkInteractorStyleTrackballCamera.h>

#include <vtkMath.h>

int main (int, char *[])
{
// Spiral tube
double vX, vY, vZ;
unsigned int nV = 256;      // No. of vertices
unsigned int nCyc = 5;      // No. of spiral cycles
double rT1 = 0.1, rT2 = 0.5;// Start/end tube radii
double rS = 2;              // Spiral radius
double h = 10;              // Height
unsigned int nTv = 8;       // No. of surface elements for each tube vertex

unsigned int i;

// Create points and cells for the spiral
vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
for(i = 0; i < nV; i++)
{
// Spiral coordinates
vX = rS * cos(2 * vtkMath::Pi() * nCyc * i / (nV - 1));
vY = rS * sin(2 * vtkMath::Pi() * nCyc * i / (nV - 1));
vZ = h * i / nV;
points->InsertPoint(i, vX, vY, vZ);
}

vtkSmartPointer<vtkCellArray> lines =
vtkSmartPointer<vtkCellArray>::New();
lines->InsertNextCell(nV);
for (i = 0; i < nV; i++)
{
lines->InsertCellPoint(i);
}

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

// Varying tube radius using sine-function
vtkSmartPointer<vtkDoubleArray>::New();
for (i=0 ;i<nV ; i++)
{
rT1 + (rT2 - rT1) * sin(vtkMath::Pi() * i / (nV - 1)));
}

// RBG array (could add Alpha channel too I guess...)
// Varying from blue to red
vtkSmartPointer<vtkUnsignedCharArray> colors =
vtkSmartPointer<vtkUnsignedCharArray>::New();
colors->SetName("Colors");
colors->SetNumberOfComponents(3);
colors->SetNumberOfTuples(nV);
for (i = 0; i < nV ;i++)
{
colors->InsertTuple3(i,
int(255 * i/ (nV - 1)),
0,
int(255 * (nV - 1 - i)/(nV - 1)) );
}

vtkSmartPointer<vtkTubeFilter> tube
= vtkSmartPointer<vtkTubeFilter>::New();
#if VTK_MAJOR_VERSION <= 5
tube->SetInput(polyData);
#else
tube->SetInputData(polyData);
#endif
tube->SetNumberOfSides(nTv);

vtkSmartPointer<vtkPolyDataMapper> mapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
mapper->SetInputConnection(tube->GetOutputPort());
mapper->ScalarVisibilityOn();
mapper->SetScalarModeToUsePointFieldData();
mapper->SelectColorArray("Colors");

vtkSmartPointer<vtkActor> actor =
vtkSmartPointer<vtkActor>::New();
actor->SetMapper(mapper);

vtkSmartPointer<vtkRenderer> renderer =
vtkSmartPointer<vtkRenderer>::New();
renderer->SetBackground(.2, .3, .4);

// Make an oblique view
renderer->GetActiveCamera()->Azimuth(30);
renderer->GetActiveCamera()->Elevation(30);
renderer->ResetCamera();

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

iren->SetRenderWindow(renWin);
renWin->SetSize(500, 500);
renWin->Render();

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

iren->Start();

return EXIT_SUCCESS;
}

Please try the new VTKExamples website.

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

find_package(VTK REQUIRED)
include(\${VTK_USE_FILE})

if(VTK_LIBRARIES)
else()
endif()

• 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: