TubesFromSplines
vtk-examples/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.
Question
If you have a question about this example, please use the VTK Discourse Forum
Code¶
TubesFromSplines.cxx
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkProperty.h>
#include <vtkNew.h>
#include <vtkParametricFunctionSource.h>
#include <vtkParametricSpline.h>
#include <vtkTubeFilter.h>
#include <vtkTupleInterpolator.h>
#include <vtkDoubleArray.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkActor.h>
#include <vtkNamedColors.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
int main(int, char*[])
{
vtkNew<vtkPoints> points;
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
vtkNew<vtkParametricSpline> spline;
spline->SetPoints(points);
vtkNew<vtkParametricFunctionSource> functionSource;
functionSource->SetParametricFunction(spline);
functionSource->SetUResolution(10 * points->GetNumberOfPoints());
functionSource->Update();
// Interpolate the scalars
double rad;
vtkNew<vtkTupleInterpolator> interpolatedRadius;
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
vtkNew<vtkDoubleArray> tubeRadius;
unsigned int n = functionSource->GetOutput()->GetNumberOfPoints();
tubeRadius->SetNumberOfTuples(n);
tubeRadius->SetName("TubeRadius");
auto tMin = interpolatedRadius->GetMinimumT();
auto tMax = interpolatedRadius->GetMaximumT();
double r;
for (unsigned int i = 0; i < n; ++i)
{
auto t = (tMax - tMin) / (n - 1) * i + tMin;
interpolatedRadius->InterpolateTuple(t, &r);
tubeRadius->SetTuple1(i, r);
}
// Add the scalars to the polydata
auto tubePolyData = functionSource->GetOutput();
tubePolyData->GetPointData()->AddArray(tubeRadius);
tubePolyData->GetPointData()->SetActiveScalars("TubeRadius");
// Create the tubes
vtkNew<vtkTubeFilter> tuber;
tuber->SetInputData(tubePolyData);
tuber->SetNumberOfSides(20);
tuber->SetVaryRadiusToVaryRadiusByAbsoluteScalar();
//--------------
// Setup actors and mappers
vtkNew<vtkPolyDataMapper> lineMapper;
lineMapper->SetInputData(tubePolyData);
lineMapper->SetScalarRange(tubePolyData->GetScalarRange());
vtkNew<vtkPolyDataMapper> tubeMapper;
tubeMapper->SetInputConnection(tuber->GetOutputPort());
tubeMapper->SetScalarRange(tubePolyData->GetScalarRange());
vtkNew<vtkActor> lineActor;
lineActor->SetMapper(lineMapper);
lineActor->GetProperty()->SetLineWidth(3);
vtkNew<vtkActor> tubeActor;
tubeActor->SetMapper(tubeMapper);
tubeActor->GetProperty()->SetOpacity(0.6);
// Setup render window, renderer, and interactor
vtkNew<vtkNamedColors> colors;
vtkNew<vtkRenderer> renderer;
renderer->UseHiddenLineRemovalOn();
vtkNew<vtkRenderWindow> renderWindow;
renderWindow->AddRenderer(renderer);
renderWindow->SetSize(640, 480);
renderWindow->SetWindowName("TubesFromSplines");
vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
renderWindowInteractor->SetRenderWindow(renderWindow);
renderer->AddActor(lineActor);
renderer->AddActor(tubeActor);
renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());
renderWindow->Render();
renderWindowInteractor->Start();
return EXIT_SUCCESS;
}
CMakeLists.txt¶
cmake_minimum_required(VERSION 3.3 FATAL_ERROR)
project(TubesFromSplines)
find_package(VTK COMPONENTS
vtkCommonColor
vtkCommonComputationalGeometry
vtkCommonCore
vtkCommonDataModel
vtkFiltersCore
vtkFiltersSources
vtkInteractionStyle
vtkRenderingContextOpenGL2
vtkRenderingCore
vtkRenderingFreeType
vtkRenderingGL2PSOpenGL2
vtkRenderingOpenGL2
QUIET
)
if (NOT VTK_FOUND)
message("Skipping TubesFromSplines: ${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(TubesFromSplines MACOSX_BUNDLE TubesFromSplines.cxx )
target_link_libraries(TubesFromSplines PRIVATE ${VTK_LIBRARIES})
else ()
# include all components
add_executable(TubesFromSplines MACOSX_BUNDLE TubesFromSplines.cxx )
target_link_libraries(TubesFromSplines PRIVATE ${VTK_LIBRARIES})
# vtk_module_autoinit is needed
vtk_module_autoinit(
TARGETS TubesFromSplines
MODULES ${VTK_LIBRARIES}
)
endif ()
Download and Build TubesFromSplines¶
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
Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.