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KochanekSpline

Repository source: KochanekSpline

Description

The vtkKochanekSpline provides three parameters 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.

Other languages

See (Java)

Question

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

Code

KochanekSpline.cxx

#include <vtkActor.h>
#include <vtkGlyph3DMapper.h>
#include <vtkKochanekSpline.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkParametricFunctionSource.h>
#include <vtkParametricSpline.h>
#include <vtkPointSource.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSphereSource.h>

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  int numberOfPoints = 10;
  vtkNew<vtkPointSource> pointSource;
  pointSource->SetNumberOfPoints(numberOfPoints);
  pointSource->Update();

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

  vtkNew<vtkKochanekSpline> xSpline;
  vtkNew<vtkKochanekSpline> ySpline;
  vtkNew<vtkKochanekSpline> zSpline;

  vtkNew<vtkParametricSpline> spline;
  spline->SetXSpline(xSpline);
  spline->SetYSpline(ySpline);
  spline->SetZSpline(zSpline);
  spline->SetPoints(points);

  vtkNew<vtkParametricFunctionSource> functionSource;
  functionSource->SetParametricFunction(spline);
  functionSource->SetUResolution(50 * numberOfPoints);
  functionSource->SetVResolution(50 * numberOfPoints);
  functionSource->SetWResolution(50 * numberOfPoints);
  functionSource->Update();

  // Setup actor and mapper
  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputConnection(functionSource->GetOutputPort());

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

  // Glyph the points
  vtkNew<vtkSphereSource> sphere;
  sphere->SetPhiResolution(21);
  sphere->SetThetaResolution(21);
  sphere->SetRadius(.02);

  // Create a polydata to store everything in
  vtkNew<vtkPolyData> polyData;
  polyData->SetPoints(points);

  vtkNew<vtkGlyph3DMapper> pointMapper;
  pointMapper->SetInputData(polyData);
  pointMapper->SetSourceConnection(sphere->GetOutputPort());

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

  // Setup render window, renderer, and interactor
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("KochanekSpline");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  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 3.12 FATAL_ERROR)

project(KochanekSpline)

find_package(VTK COMPONENTS 
  CommonColor
  CommonComputationalGeometry
  CommonCore
  CommonDataModel
  FiltersSources
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "KochanekSpline: 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(KochanekSpline MACOSX_BUNDLE KochanekSpline.cxx )
  target_link_libraries(KochanekSpline PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS KochanekSpline
  MODULES ${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.