CellPicking
VTKExamples/Cxx/Picking/CellPicking
Description¶
This example demonstrates how to get the coordinates of the point on an actor that is clicked with the left mouse button. It also indicates which cell the selected point belongs to by highlighting the edges of that cell.
Code¶
CellPicking.cxx
#include <vtkVersion.h> #include <vtkSmartPointer.h> #include <vtkRendererCollection.h> #include <vtkDataSetMapper.h> #include <vtkUnstructuredGrid.h> #include <vtkIdTypeArray.h> #include <vtkTriangleFilter.h> #include <vtkPolyDataMapper.h> #include <vtkActor.h> #include <vtkCommand.h> #include <vtkRenderWindow.h> #include <vtkRenderer.h> #include <vtkRenderWindowInteractor.h> #include <vtkPolyData.h> #include <vtkPoints.h> #include <vtkCellArray.h> #include <vtkPlaneSource.h> #include <vtkCellPicker.h> #include <vtkInteractorStyleTrackballCamera.h> #include <vtkProperty.h> #include <vtkSelectionNode.h> #include <vtkSelection.h> #include <vtkExtractSelection.h> #include <vtkObjectFactory.h> // Catch mouse events class MouseInteractorStyle : public vtkInteractorStyleTrackballCamera { public: static MouseInteractorStyle* New(); MouseInteractorStyle() { selectedMapper = vtkSmartPointer<vtkDataSetMapper>::New(); selectedActor = vtkSmartPointer<vtkActor>::New(); } virtual void OnLeftButtonDown() { // Get the location of the click (in window coordinates) int* pos = this->GetInteractor()->GetEventPosition(); vtkSmartPointer<vtkCellPicker> picker = vtkSmartPointer<vtkCellPicker>::New(); picker->SetTolerance(0.0005); // Pick from this location. picker->Pick(pos[0], pos[1], 0, this->GetDefaultRenderer()); double* worldPosition = picker->GetPickPosition(); std::cout << "Cell id is: " << picker->GetCellId() << std::endl; if(picker->GetCellId() != -1) { std::cout << "Pick position is: " << worldPosition[0] << " " << worldPosition[1] << " " << worldPosition[2] << endl; vtkSmartPointer<vtkIdTypeArray> ids = vtkSmartPointer<vtkIdTypeArray>::New(); ids->SetNumberOfComponents(1); ids->InsertNextValue(picker->GetCellId()); vtkSmartPointer<vtkSelectionNode> selectionNode = vtkSmartPointer<vtkSelectionNode>::New(); selectionNode->SetFieldType(vtkSelectionNode::CELL); selectionNode->SetContentType(vtkSelectionNode::INDICES); selectionNode->SetSelectionList(ids); vtkSmartPointer<vtkSelection> selection = vtkSmartPointer<vtkSelection>::New(); selection->AddNode(selectionNode); vtkSmartPointer<vtkExtractSelection> extractSelection = vtkSmartPointer<vtkExtractSelection>::New(); #if VTK_MAJOR_VERSION <= 5 extractSelection->SetInput(0, this->Data); extractSelection->SetInput(1, selection); #else extractSelection->SetInputData(0, this->Data); extractSelection->SetInputData(1, selection); #endif extractSelection->Update(); // In selection vtkSmartPointer<vtkUnstructuredGrid> selected = vtkSmartPointer<vtkUnstructuredGrid>::New(); selected->ShallowCopy(extractSelection->GetOutput()); std::cout << "There are " << selected->GetNumberOfPoints() << " points in the selection." << std::endl; std::cout << "There are " << selected->GetNumberOfCells() << " cells in the selection." << std::endl; #if VTK_MAJOR_VERSION <= 5 selectedMapper->SetInputConnection( selected->GetProducerPort()); #else selectedMapper->SetInputData(selected); #endif selectedActor->SetMapper(selectedMapper); selectedActor->GetProperty()->EdgeVisibilityOn(); selectedActor->GetProperty()->SetEdgeColor(1,0,0); selectedActor->GetProperty()->SetLineWidth(3); this->Interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer()->AddActor(selectedActor); } // Forward events vtkInteractorStyleTrackballCamera::OnLeftButtonDown(); } vtkSmartPointer<vtkPolyData> Data; vtkSmartPointer<vtkDataSetMapper> selectedMapper; vtkSmartPointer<vtkActor> selectedActor; }; vtkStandardNewMacro(MouseInteractorStyle); int main (int, char *[]) { vtkSmartPointer<vtkPlaneSource> planeSource = vtkSmartPointer<vtkPlaneSource>::New(); planeSource->Update(); vtkSmartPointer<vtkTriangleFilter> triangleFilter = vtkSmartPointer<vtkTriangleFilter>::New(); triangleFilter->SetInputConnection(planeSource->GetOutputPort()); triangleFilter->Update(); vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New(); mapper->SetInputConnection(triangleFilter->GetOutputPort()); vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New(); actor->GetProperty()->SetColor(0,1,0); //green actor->SetMapper(mapper); vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New(); vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New(); renderWindow->AddRenderer(renderer); vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = vtkSmartPointer<vtkRenderWindowInteractor>::New(); renderWindowInteractor->SetRenderWindow(renderWindow); renderWindowInteractor->Initialize(); // Set the custom stype to use for interaction. vtkSmartPointer<MouseInteractorStyle> style = vtkSmartPointer<MouseInteractorStyle>::New(); style->SetDefaultRenderer(renderer); style->Data = triangleFilter->GetOutput(); renderWindowInteractor->SetInteractorStyle(style); renderer->AddActor(actor); renderer->ResetCamera(); renderer->SetBackground(0,0,1); // Blue renderWindow->Render(); renderWindowInteractor->Start(); return EXIT_SUCCESS; }
CMakeLists.txt¶
cmake_minimum_required(VERSION 2.8) PROJECT(CellPicking) find_package(VTK REQUIRED) include(${VTK_USE_FILE}) add_executable(CellPicking MACOSX_BUNDLE CellPicking.cxx) target_link_libraries(CellPicking ${VTK_LIBRARIES})
Download and Build CellPicking¶
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 CellPicking and its CMakeLists.txt file. Once the tarball CellPicking.tar has been downloaded and extracted,
cd CellPicking/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:
./CellPicking
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.