TubesFromSplines
VTKExamples/Cxx/VisualizationAlgorithms/TubesFromSplines
Description¶
This example shows how to interpolate a set of points and generate tubes around the resulting polyline. Scalars associated with the points are also interpolated and used to vary the radius of the tube.
Note
This example was inspired by a question asked by ''Adam Sankowski''.
Code¶
TubesFromSplines.cxx
#include <vtkSmartPointer.h> #include <vtkVersion.h> #include <vtkParametricFunctionSource.h> #include <vtkTupleInterpolator.h> #include <vtkTubeFilter.h> #include <vtkParametricSpline.h> #include <vtkDoubleArray.h> #include <vtkPoints.h> #include <vtkPolyData.h> #include <vtkPointData.h> #include <vtkPolyDataMapper.h> #include <vtkActor.h> #include <vtkRenderWindow.h> #include <vtkRenderer.h> #include <vtkRenderWindowInteractor.h> int main(int, char *[]) { vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New(); points->InsertPoint(0,1,0,0); points->InsertPoint(1,2,0,0); points->InsertPoint(2,3,1,0); points->InsertPoint(3,4,1,0); points->InsertPoint(4,5,0,0); points->InsertPoint(5,6,0,0); // Fit a spline to the points vtkSmartPointer<vtkParametricSpline> spline = vtkSmartPointer<vtkParametricSpline>::New(); spline->SetPoints(points); vtkSmartPointer<vtkParametricFunctionSource> functionSource = vtkSmartPointer<vtkParametricFunctionSource>::New(); functionSource->SetParametricFunction(spline); functionSource->SetUResolution(10 * points->GetNumberOfPoints()); functionSource->Update(); // Interpolate the scalars double rad; vtkSmartPointer<vtkTupleInterpolator> interpolatedRadius = vtkSmartPointer<vtkTupleInterpolator> ::New(); interpolatedRadius->SetInterpolationTypeToLinear(); interpolatedRadius->SetNumberOfComponents(1); rad = .2; interpolatedRadius->AddTuple(0,&rad); rad = .2; interpolatedRadius->AddTuple(1,&rad); rad = .2; interpolatedRadius->AddTuple(2,&rad); rad = .1; interpolatedRadius->AddTuple(3,&rad); rad = .1; interpolatedRadius->AddTuple(4,&rad); rad = .1; interpolatedRadius->AddTuple(5,&rad); // Generate the radius scalars vtkSmartPointer<vtkDoubleArray> tubeRadius = vtkSmartPointer<vtkDoubleArray>::New(); unsigned int n = functionSource->GetOutput()->GetNumberOfPoints(); tubeRadius->SetNumberOfTuples(n); tubeRadius->SetName("TubeRadius"); double tMin = interpolatedRadius->GetMinimumT(); double tMax = interpolatedRadius->GetMaximumT(); double r; for (unsigned int i = 0; i < n; ++i) { double t = (tMax - tMin) / (n - 1) * i + tMin; interpolatedRadius->InterpolateTuple(t, &r); tubeRadius->SetTuple1(i, r); } // Add the scalars to the polydata vtkSmartPointer<vtkPolyData> tubePolyData = vtkSmartPointer<vtkPolyData>::New(); tubePolyData = functionSource->GetOutput(); tubePolyData->GetPointData()->AddArray(tubeRadius); tubePolyData->GetPointData()->SetActiveScalars("TubeRadius"); // Create the tubes vtkSmartPointer<vtkTubeFilter> tuber = vtkSmartPointer<vtkTubeFilter>::New(); #if VTK_MAJOR_VERSION <= 5 tuber->SetInput(tubePolyData); #else tuber->SetInputData(tubePolyData); #endif tuber->SetNumberOfSides(20); tuber->SetVaryRadiusToVaryRadiusByAbsoluteScalar(); //-------------- // Setup actors and mappers vtkSmartPointer<vtkPolyDataMapper> lineMapper = vtkSmartPointer<vtkPolyDataMapper>::New(); #if VTK_MAJOR_VERSION <= 5 lineMapper->SetInput(tubePolyData); #else lineMapper->SetInputData(tubePolyData); #endif lineMapper->SetScalarRange(tubePolyData->GetScalarRange()); vtkSmartPointer<vtkPolyDataMapper> tubeMapper = vtkSmartPointer<vtkPolyDataMapper>::New(); tubeMapper->SetInputConnection(tuber->GetOutputPort()); tubeMapper->SetScalarRange(tubePolyData->GetScalarRange()); vtkSmartPointer<vtkActor> lineActor = vtkSmartPointer<vtkActor>::New(); lineActor->SetMapper(lineMapper); vtkSmartPointer<vtkActor> tubeActor = vtkSmartPointer<vtkActor>::New(); tubeActor->SetMapper(tubeMapper); // 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(lineActor); renderer->AddActor(tubeActor); renderer->SetBackground(.4, .5, .6); renderWindow->Render(); renderWindowInteractor->Start(); return EXIT_SUCCESS; }
CMakeLists.txt¶
cmake_minimum_required(VERSION 2.8) PROJECT(TubesFromSplines) find_package(VTK REQUIRED) include(${VTK_USE_FILE}) add_executable(TubesFromSplines MACOSX_BUNDLE TubesFromSplines.cxx) target_link_libraries(TubesFromSplines ${VTK_LIBRARIES})
Download and Build TubesFromSplines¶
Danger
The generation of tar files has not been ported to the new VTKExamples. Some tarballs may be missing or out-of-date.
Click here to download TubesFromSplines and its CMakeLists.txt file. Once the tarball TubesFromSplines.tar has been downloaded and extracted,
cd TubesFromSplines/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:
./TubesFromSplines
WINDOWS USERS PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.