VTK/Examples/Cxx/Widgets/ContourWidget

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VTK Examples Baseline Widgets TestContourWidget.png

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.

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;
}

Please try the new VTKExamples website.

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)
 
if(VTK_LIBRARIES)
  target_link_libraries(ContourWidget ${VTK_LIBRARIES})
else()
  target_link_libraries(ContourWidget vtkHybrid vtkWidgets)
endif()

Download and Build ContourWidget

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.