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
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.