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
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.