FitSplineToCutterOutput
VTKEx/Cxx/PolyData/FitSplineToCutterOutput
Description¶
This examples cuts a vtkPolydata and fits a vtkKochanekSpline to the resulting polylines. The cut lines are passed through vtkStripper to make them into connected polylines. Then, the lines are passed through vtkTubeFilter to improve the visualization.
The examples takes an optional argument that specifies a vtk polydata file (.vtp). If run without an argument, it processes a sphere.
Question
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Code¶
FitSplineToCutterOutput.cxx
#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkCellArray.h>
#ifdef VTK_CELL_ARRAY_V2
#include <vtkCellArrayIterator.h>
#endif // VTK_CELL_ARRAY_V2
#include <vtkCutter.h>
#include <vtkKochanekSpline.h>
#include <vtkPlane.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkSpline.h>
#include <vtkSplineFilter.h>
#include <vtkStripper.h>
#include <vtkTubeFilter.h>
#include <vtkXMLPolyDataReader.h>
#include <vtkNamedColors.h>
int main(int argc, char* argv[])
{
vtkSmartPointer<vtkPolyData> polyData;
if (argc > 1)
{
auto reader = vtkSmartPointer<vtkXMLPolyDataReader>::New();
reader->SetFileName(argv[1]);
reader->Update();
polyData = reader->GetOutput();
}
else
{
auto modelSource = vtkSmartPointer<vtkSphereSource>::New();
modelSource->Update();
polyData = modelSource->GetOutput();
}
double length = polyData->GetLength();
auto plane = vtkSmartPointer<vtkPlane>::New();
plane->SetNormal(0, 1, 1);
plane->SetOrigin(polyData->GetCenter());
auto cutter = vtkSmartPointer<vtkCutter>::New();
cutter->SetInputData(polyData);
cutter->SetCutFunction(plane);
cutter->GenerateValues(1, 0.0, 0.0);
auto colors = vtkSmartPointer<vtkNamedColors>::New();
auto modelMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
modelMapper->SetInputData(polyData);
auto model = vtkSmartPointer<vtkActor>::New();
model->SetMapper(modelMapper);
model->GetProperty()->SetColor(colors->GetColor3d("Tomato").GetData());
model->GetProperty()->SetInterpolationToFlat();
auto stripper = vtkSmartPointer<vtkStripper>::New();
stripper->SetInputConnection(cutter->GetOutputPort());
auto spline = vtkSmartPointer<vtkKochanekSpline>::New();
spline->SetDefaultTension(.5);
auto sf = vtkSmartPointer<vtkSplineFilter>::New();
sf->SetInputConnection(stripper->GetOutputPort());
sf->SetSubdivideToSpecified();
sf->SetNumberOfSubdivisions(50);
sf->SetSpline(spline);
sf->GetSpline()->ClosedOn();
auto tubes = vtkSmartPointer<vtkTubeFilter>::New();
tubes->SetInputConnection(sf->GetOutputPort());
tubes->SetNumberOfSides(8);
tubes->SetRadius(length / 100.0);
auto linesMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
linesMapper->SetInputConnection(tubes->GetOutputPort());
linesMapper->ScalarVisibilityOff();
auto lines = vtkSmartPointer<vtkActor>::New();
lines->SetMapper(linesMapper);
lines->GetProperty()->SetColor(colors->GetColor3d("Banana").GetData());
auto renderer = vtkSmartPointer<vtkRenderer>::New();
renderer->UseHiddenLineRemovalOn();
auto renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
auto interactor = vtkSmartPointer<vtkRenderWindowInteractor>::New();
interactor->SetRenderWindow(renderWindow);
// Add the actors to the renderer
renderer->AddActor(model);
renderer->AddActor(lines);
renderer->ResetCamera();
renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());
renderer->GetActiveCamera()->Azimuth(300);
renderer->GetActiveCamera()->Elevation(30);
renderWindow->AddRenderer(renderer);
renderWindow->SetSize(640, 480);
// This starts the event loop and as a side effect causes an initial
// render.
renderWindow->Render();
interactor->Start();
// Extract the lines from the polydata
vtkIdType numberOfLines = cutter->GetOutput()->GetNumberOfLines();
std::cout << "-----------Lines without using vtkStripper" << std::endl;
if (numberOfLines == 1)
{
std::cout << "There is " << numberOfLines << " line in the polydata"
<< std::endl;
}
else
{
std::cout << "There are " << numberOfLines << " lines in the polydata"
<< std::endl;
}
numberOfLines = stripper->GetOutput()->GetNumberOfLines();
vtkPoints* points = stripper->GetOutput()->GetPoints();
vtkCellArray* cells = stripper->GetOutput()->GetLines();
std::cout << "-----------Lines using vtkStripper" << std::endl;
if (numberOfLines == 1)
{
std::cout << "There is " << numberOfLines << " line in the polydata"
<< std::endl;
}
else
{
std::cout << "There are " << numberOfLines << " lines in the polydata"
<< std::endl;
}
#ifdef VTK_CELL_ARRAY_V2
// Newer versions of vtkCellArray prefer local iterators:
auto cellIter = vtk::TakeSmartPointer(cells->NewIterator());
for (cellIter->GoToFirstCell();
!cellIter->IsDoneWithTraversal();
cellIter->GoToNextCell())
{
std::cout << "Line " << cellIter->GetCurrentCellId() << ":\n";
vtkIdList *cell = cellIter->GetCurrentCell();
for (vtkIdType i = 0; i < cell->GetNumberOfIds(); ++i)
{
double point[3];
points->GetPoint(cell->GetId(i), point);
std::cout << "\t(" << point[0] << ", " << point[1] << ", " << point[2]
<< ")" << std::endl;
}
}
#else // VTK_CELL_ARRAY_V2
// Older implementations of vtkCellArray use internal iterator APIs (not
// thread safe):
vtkIdType* indices;
vtkIdType numberOfPoints;
unsigned int lineCount = 0;
for (cells->InitTraversal(); cells->GetNextCell(numberOfPoints, indices);
lineCount++)
{
std::cout << "Line " << lineCount << ": " << std::endl;
for (vtkIdType i = 0; i < numberOfPoints; i++)
{
double point[3];
points->GetPoint(indices[i], point);
std::cout << "\t(" << point[0] << ", " << point[1] << ", " << point[2]
<< ")" << std::endl;
}
}
#endif // VTK_CELL_ARRAY_V2
return EXIT_SUCCESS;
}
CMakeLists.txt¶
cmake_minimum_required(VERSION 3.3 FATAL_ERROR)
project(FitSplineToCutterOutput)
find_package(VTK COMPONENTS
vtkvtkCommonColor
vtkvtkCommonComputationalGeometry
vtkvtkCommonCore
vtkvtkCommonDataModel
vtkvtkFiltersCore
vtkvtkFiltersGeneral
vtkvtkFiltersSources
vtkvtkIOXML
vtkvtkInteractionStyle
vtkvtkRenderingContextOpenGL2
vtkvtkRenderingCore
vtkvtkRenderingFreeType
vtkvtkRenderingGL2PSOpenGL2
vtkvtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
message("Skipping FitSplineToCutterOutput: ${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(FitSplineToCutterOutput MACOSX_BUNDLE FitSplineToCutterOutput.cxx )
target_link_libraries(FitSplineToCutterOutput PRIVATE ${VTK_LIBRARIES})
else ()
# include all components
add_executable(FitSplineToCutterOutput MACOSX_BUNDLE FitSplineToCutterOutput.cxx )
target_link_libraries(FitSplineToCutterOutput PRIVATE ${VTK_LIBRARIES})
# vtk_module_autoinit is needed
vtk_module_autoinit(
TARGETS FitSplineToCutterOutput
MODULES ${VTK_LIBRARIES}
)
endif ()
Download and Build FitSplineToCutterOutput¶
Click here to download FitSplineToCutterOutput and its CMakeLists.txt file. Once the tarball FitSplineToCutterOutput.tar has been downloaded and extracted,
cd FitSplineToCutterOutput/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:
./FitSplineToCutterOutput
WINDOWS USERS
Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.