ContourWidget
VTKExamples/Cxx/Widgets/ContourWidget
Description¶
This example generates a set of points which lie on a circle, and the contour through these points. This contour can be interactively warped/modified by dragging the control points.
Code¶
ContourWidget.cxx
#include <vtkSmartPointer.h> // To setup the ContourWidget and its representation: #include <vtkContourWidget.h> #include <vtkProperty.h> #include <vtkOrientedGlyphContourRepresentation.h> // To create the geometry: #include <vtkPolyData.h> #include <vtkCellArray.h> #include <vtkPoints.h> #include <vtkMath.h> // Usual VTK pipeline elements: #include <vtkRenderer.h> #include <vtkRenderWindow.h> #include <vtkRenderWindowInteractor.h> #include <vtkInteractorStyleTrackballCamera.h> int main( int argc, char *argv[] ) { // Create the contour widget vtkSmartPointer<vtkContourWidget> contourWidget = vtkSmartPointer<vtkContourWidget>::New(); // Override the default representation for the contour widget to customize its look vtkSmartPointer<vtkOrientedGlyphContourRepresentation> contourRepresentation = vtkSmartPointer<vtkOrientedGlyphContourRepresentation>::New(); contourRepresentation->GetLinesProperty()->SetColor(1, 0, 0); // Set color to red contourWidget->SetRepresentation(contourRepresentation); // Generate a set of points arranged in a circle int numPts = 10; vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New(); for (int i = 0; i < numPts; i++) { // Create numPts points evenly spread around a circumference of radius 0.1 const double angle = 2.0*vtkMath::Pi()*i/numPts; points->InsertPoint(static_cast<vtkIdType>(i), 0.1*cos(angle), 0.1*sin(angle), 0.0 ); } // Create a cell array to connect the points into meaningful geometry vtkIdType* vertexIndices = new vtkIdType[numPts+1]; for (int i = 0; i < numPts; i++) { vertexIndices[i] = static_cast<vtkIdType>(i); } // Set the last vertex to 0; this means the last line segment will join the 19th point (vertices[19]) // with the first one (vertices[0]), thus closing the circle. vertexIndices[numPts] = 0; vtkSmartPointer<vtkCellArray> lines = vtkSmartPointer<vtkCellArray>::New(); lines->InsertNextCell(numPts+1, vertexIndices); // Create polydata to hold the geometry just created, and populate it vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New(); polydata->SetPoints(points); polydata->SetLines(lines); // Create the renderer to visualize the scene vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New(); renderer->SetBackground(0.1, 0.2, 0.4); // Set a dark blue background (default is black) // Create the GUI window to hold the rendered scene vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New(); renderWindow->AddRenderer(renderer); // Create the events manager for the renderer window vtkSmartPointer<vtkRenderWindowInteractor> interactor = vtkSmartPointer<vtkRenderWindowInteractor>::New(); interactor->SetRenderWindow(renderWindow); // Use the "trackball camera" interactor style, rather than the default "joystick camera" vtkSmartPointer<vtkInteractorStyleTrackballCamera> style = vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New(); interactor->SetInteractorStyle(style); // Set up the contour widget within the visualization pipeline just assembled contourWidget->SetInteractor(interactor); contourWidget->On(); // Turn on the interactor observer contourWidget->Initialize(polydata); renderer->ResetCamera(); // Reposition camera to fit the scene elements // Start the interaction interactor->Start(); return EXIT_SUCCESS; }
CMakeLists.txt¶
cmake_minimum_required(VERSION 2.8) PROJECT(ContourWidget) find_package(VTK REQUIRED) include(${VTK_USE_FILE}) add_executable(ContourWidget MACOSX_BUNDLE ContourWidget.cxx) target_link_libraries(ContourWidget ${VTK_LIBRARIES})
Download and Build ContourWidget¶
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 ContourWidget and its CMakeLists.txt file. Once the tarball ContourWidget.tar has been downloaded and extracted,
cd ContourWidget/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:
./ContourWidget
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.