KochanekSpline

VTKExamples/Cxx/PolyData/KochanekSpline


Description

The vtkKochanekSpline provides three parametes to control the shape of the spline:

  1. tension - Changes the length of the tangent vector
  2. bias - Primarily changes the direction of the tangent vector
  3. continuity - Changes the sharpness in change between tangents

Seealso

KochanekSplineDemo provides sliders to change the three parameters.

Seealso

This wikipedia article describes the controlsin detail.

Code

KochanekSpline.cxx

#include <vtkSmartPointer.h>
#include <vtkKochanekSpline.h>
#include <vtkParametricSpline.h>
#include <vtkParametricFunctionSource.h>

#include <vtkPointSource.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>

#include <vtkGlyph3DMapper.h>
#include <vtkSphereSource.h>
#include <vtkNamedColors.h>

int main(int, char *[])
{
  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  int numberOfPoints = 10;
  vtkSmartPointer<vtkPointSource> pointSource = 
    vtkSmartPointer<vtkPointSource>::New();
  pointSource->SetNumberOfPoints(numberOfPoints);
  pointSource->Update();

  vtkPoints* points = pointSource->GetOutput()->GetPoints();

  vtkSmartPointer<vtkKochanekSpline> xSpline = 
    vtkSmartPointer<vtkKochanekSpline>::New();
  vtkSmartPointer<vtkKochanekSpline> ySpline = 
    vtkSmartPointer<vtkKochanekSpline>::New();
  vtkSmartPointer<vtkKochanekSpline> zSpline = 
    vtkSmartPointer<vtkKochanekSpline>::New();

  vtkSmartPointer<vtkParametricSpline> spline = 
    vtkSmartPointer<vtkParametricSpline>::New();
  spline->SetXSpline(xSpline);
  spline->SetYSpline(ySpline);
  spline->SetZSpline(zSpline);
  spline->SetPoints(points);

  vtkSmartPointer<vtkParametricFunctionSource> functionSource = 
      vtkSmartPointer<vtkParametricFunctionSource>::New();
  functionSource->SetParametricFunction(spline);
  functionSource->SetUResolution(50 * numberOfPoints);
  functionSource->SetVResolution(50 * numberOfPoints);
  functionSource->SetWResolution(50 * numberOfPoints);
  functionSource->Update();

  // Setup actor and mapper
  vtkSmartPointer<vtkPolyDataMapper> mapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(functionSource->GetOutputPort());

  vtkSmartPointer<vtkActor> actor = 
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
  actor->GetProperty()->SetColor(colors->GetColor3d("DarkSlateGrey").GetData());
  actor->GetProperty()->SetLineWidth(3.0);

  // Glyph the points
  vtkSmartPointer<vtkSphereSource> sphere =
    vtkSmartPointer<vtkSphereSource>::New();
  sphere->SetPhiResolution(21);
  sphere->SetThetaResolution(21);
  sphere->SetRadius(.02);

  // Create a polydata to store everything in
  vtkSmartPointer<vtkPolyData> polyData =
    vtkSmartPointer<vtkPolyData>::New();
  polyData->SetPoints(points);

  vtkSmartPointer<vtkGlyph3DMapper> pointMapper =
    vtkSmartPointer<vtkGlyph3DMapper>::New();
  pointMapper->SetInputData(polyData);
  pointMapper->SetSourceConnection(sphere->GetOutputPort());

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

  // Setup render window, renderer, and interactor
  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  renderer->AddActor(actor);
  renderer->AddActor(pointActor);;
  renderer->SetBackground(colors->GetColor3d("Silver").GetData());

  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(KochanekSpline)

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

add_executable(KochanekSpline MACOSX_BUNDLE KochanekSpline.cxx )

target_link_libraries(KochanekSpline ${VTK_LIBRARIES})

Download and Build KochanekSpline

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

cd KochanekSpline/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:

./KochanekSpline

WINDOWS USERS

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