ThresholdCells
VTKExamples/Cxx/PolyData/ThresholdCells
Code¶
ThresholdCells.cxx
#include <vtkVersion.h> #include <vtkIntArray.h> #include <vtkCellData.h> #include <vtkTriangle.h> #include <vtkCellArray.h> #include <vtkPoints.h> #include <vtkPolyData.h> #include <vtkUnstructuredGrid.h> #include <vtkPointData.h> #include <vtkSmartPointer.h> #include <vtkThreshold.h> int main(int, char *[]) { vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New(); points->InsertNextPoint(0,0,0); points->InsertNextPoint(1,1,1); points->InsertNextPoint(2,2,2); points->InsertNextPoint(3,3,3); points->InsertNextPoint(4,4,4); // Create three triangles vtkSmartPointer<vtkTriangle> triangle0 = vtkSmartPointer<vtkTriangle>::New(); triangle0->GetPointIds()->SetId ( 0, 0 ); triangle0->GetPointIds()->SetId ( 1, 1 ); triangle0->GetPointIds()->SetId ( 2, 2 ); vtkSmartPointer<vtkTriangle> triangle1 = vtkSmartPointer<vtkTriangle>::New(); triangle1->GetPointIds()->SetId ( 0, 1 ); triangle1->GetPointIds()->SetId ( 1, 2 ); triangle1->GetPointIds()->SetId ( 2, 3 ); vtkSmartPointer<vtkTriangle> triangle2 = vtkSmartPointer<vtkTriangle>::New(); triangle2->GetPointIds()->SetId ( 0, 2 ); triangle2->GetPointIds()->SetId ( 1, 3 ); triangle2->GetPointIds()->SetId ( 2, 4 ); // Add the triangles to a cell array vtkSmartPointer<vtkCellArray> triangles = vtkSmartPointer<vtkCellArray>::New(); triangles->InsertNextCell ( triangle0 ); triangles->InsertNextCell ( triangle1 ); triangles->InsertNextCell ( triangle2 ); // Setup index array vtkSmartPointer<vtkIntArray> index = vtkSmartPointer<vtkIntArray>::New(); index->SetNumberOfComponents(1); index->SetName("index"); index->InsertNextValue(0); index->InsertNextValue(1); index->InsertNextValue(2); // Add points, cells and index array to a polydata vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New(); polydata->SetPoints(points); polydata->SetPolys(triangles); polydata->GetCellData()->AddArray(index); std::cout << "There are " << polydata->GetNumberOfCells() << " cells before thresholding." << std::endl; vtkSmartPointer<vtkThreshold> threshold = vtkSmartPointer<vtkThreshold>::New(); #if VTK_MAJOR_VERSION <= 5 threshold->SetInput(polydata); #else threshold->SetInputData(polydata); #endif threshold->ThresholdByLower(1); // doesn't work because the array is not added as SCALARS, i.e. via SetScalars // threshold->SetInputArrayToProcess(0, 0, 0, vtkDataObject::FIELD_ASSOCIATION_CELLS, vtkDataSetAttributes::SCALARS); // use like this: threshold->SetInputArrayToProcess(0, 0, 0, vtkDataObject::FIELD_ASSOCIATION_CELLS, "index"); threshold->Update(); vtkUnstructuredGrid* thresholdedPolydata = threshold->GetOutput(); std::cout << "There are " << thresholdedPolydata->GetNumberOfCells() << " cells after thresholding." << std::endl; return EXIT_SUCCESS; }
CMakeLists.txt¶
cmake_minimum_required(VERSION 2.8) PROJECT(ThresholdCells) find_package(VTK REQUIRED) include(${VTK_USE_FILE}) add_executable(ThresholdCells MACOSX_BUNDLE ThresholdCells.cxx) target_link_libraries(ThresholdCells ${VTK_LIBRARIES})
Download and Build ThresholdCells¶
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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 ThresholdCells and its CMakeLists.txt file. Once the tarball ThresholdCells.tar has been downloaded and extracted,
cd ThresholdCells/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:
./ThresholdCells
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.