ExtractEdges
VTKExamples/Cxx/Meshes/ExtractEdges
Description¶
This example shows how to extract the edges from a PolyData. In this case, we convert a sphere into a wireframe sphere. We demonstrate how to traverse the resulting edges.
Code¶
ExtractEdges.cxx
#include <vtkSmartPointer.h> #include <vtkPolyData.h> #include <vtkExtractEdges.h> #include <vtkSphereSource.h> #include <vtkCellArray.h> #include <vtkPoints.h> #include <vtkPolyDataMapper.h> #include <vtkActor.h> #include <vtkRenderWindow.h> #include <vtkRenderer.h> #include <vtkRenderWindowInteractor.h> #include <vtkLine.h> int main(int, char *[]) { vtkSmartPointer<vtkSphereSource> sphereSource = vtkSmartPointer<vtkSphereSource>::New(); sphereSource->Update(); std::cout << "Sphere" << endl << "----------" << endl; std::cout << "There are " << sphereSource->GetOutput()->GetNumberOfCells() << " cells." << std::endl; std::cout << "There are " << sphereSource->GetOutput()->GetNumberOfPoints() << " points." << std::endl; vtkSmartPointer<vtkExtractEdges> extractEdges = vtkSmartPointer<vtkExtractEdges>::New(); extractEdges->SetInputConnection(sphereSource->GetOutputPort()); extractEdges->Update(); vtkCellArray* lines= extractEdges->GetOutput()->GetLines(); vtkPoints* points = extractEdges->GetOutput()->GetPoints(); std::cout << std::endl << "Edges" << endl << "----------" << std::endl; std::cout << "There are " << lines->GetNumberOfCells() << " cells." << std::endl; std::cout << "There are " << points->GetNumberOfPoints() << " points." << std::endl; // Traverse all of the edges for(vtkIdType i = 0; i < extractEdges->GetOutput()->GetNumberOfCells(); i++) { //std::cout << "Type: " << extractEdges->GetOutput()->GetCell(i)->GetClassName() << std::endl; vtkSmartPointer<vtkLine> line = vtkLine::SafeDownCast(extractEdges->GetOutput()->GetCell(i)); std::cout << "Line " << i << " : " << *line << std::endl; } // Visualize the edges // Create a mapper and actor vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New(); mapper->SetInputConnection(extractEdges->GetOutputPort()); vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New(); actor->SetMapper(mapper); // Create a renderer, render window, 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); // Add the actor to the scene renderer->AddActor(actor); renderer->SetBackground(1,1,1); // Background color white // Render and interact renderWindow->Render(); renderWindowInteractor->Start(); return EXIT_SUCCESS; }
CMakeLists.txt¶
cmake_minimum_required(VERSION 2.8) PROJECT(ExtractEdges) find_package(VTK REQUIRED) include(${VTK_USE_FILE}) add_executable(ExtractEdges MACOSX_BUNDLE ExtractEdges.cxx) target_link_libraries(ExtractEdges ${VTK_LIBRARIES})
Download and Build ExtractEdges¶
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 ExtractEdges and its CMakeLists.txt file. Once the tarball ExtractEdges.tar has been downloaded and extracted,
cd ExtractEdges/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:
./ExtractEdges
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.