ConstrainedDelaunay2D
VTKExamples/Cxx/Filtering/ConstrainedDelaunay2D
Description
Perform a 2D Delaunay triangulation respecting a specified boundary. This examples constructs a 10x10 grid of points. It then defines a polygon that uses the points in the grid. We want to triangulate all of the points except the region inside the boundary of the polygon. We expect a rectangular hole of size 4x3 in the resulting triangulated plane.
Code
ConstrainedDelaunay2D.cxx
#include <vtkVersion.h>
#include <vtkCellArray.h>
#include <vtkProperty.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolygon.h>
#include <vtkSmartPointer.h>
#include <vtkDelaunay2D.h>
#include <vtkMath.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
int main(int, char *[])
{
// Generate a 10 x 10 grid of points
vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();
for(unsigned int x = 0; x < 10; x++)
{
for(unsigned int y = 0; y < 10; y++)
{
points->InsertNextPoint(x + vtkMath::Random(-.25, .25),
y + vtkMath::Random(-.25,.25),
0);
}
}
vtkSmartPointer<vtkPolyData> aPolyData =
vtkSmartPointer<vtkPolyData>::New();
aPolyData->SetPoints(points);
// Create a cell array to store the polygon in
vtkSmartPointer<vtkCellArray> aCellArray =
vtkSmartPointer<vtkCellArray>::New();
// Define a polygonal hole with a clockwise polygon
vtkSmartPointer<vtkPolygon> aPolygon =
vtkSmartPointer<vtkPolygon>::New();
aPolygon->GetPointIds()->InsertNextId(22);
aPolygon->GetPointIds()->InsertNextId(23);
aPolygon->GetPointIds()->InsertNextId(24);
aPolygon->GetPointIds()->InsertNextId(25);
aPolygon->GetPointIds()->InsertNextId(35);
aPolygon->GetPointIds()->InsertNextId(45);
aPolygon->GetPointIds()->InsertNextId(44);
aPolygon->GetPointIds()->InsertNextId(43);
aPolygon->GetPointIds()->InsertNextId(42);
aPolygon->GetPointIds()->InsertNextId(32);
aCellArray->InsertNextCell(aPolygon);
// Create a polydata to store the boundary. The points must be the
// same as the points we will triangulate.
vtkSmartPointer<vtkPolyData> boundary =
vtkSmartPointer<vtkPolyData>::New();
boundary->SetPoints(aPolyData->GetPoints());
boundary->SetPolys(aCellArray);
// Triangulate the grid points
vtkSmartPointer<vtkDelaunay2D> delaunay =
vtkSmartPointer<vtkDelaunay2D>::New();
#if VTK_MAJOR_VERSION <= 5
delaunay->SetInput(aPolyData);
delaunay->SetSource(boundary);
#else
delaunay->SetInputData(aPolyData);
delaunay->SetSourceData(boundary);
#endif
delaunay->Update();
// Visualize
vtkSmartPointer<vtkPolyDataMapper> meshMapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
meshMapper->SetInputConnection(delaunay->GetOutputPort());
vtkSmartPointer<vtkActor> meshActor =
vtkSmartPointer<vtkActor>::New();
meshActor->SetMapper(meshMapper);
//meshActor->GetProperty()->SetEdgeColor(0,0,1); // Why aren't the edges aren't visible unless we set the representation to wireframe?
//meshActor->GetProperty()->SetInterpolationToFlat();
meshActor->GetProperty()->SetRepresentationToWireframe();
vtkSmartPointer<vtkPolyDataMapper> boundaryMapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
#if VTK_MAJOR_VERSION <= 5
boundaryMapper->SetInputConnection(boundary->GetProducerPort());
#else
boundaryMapper->SetInputData(boundary);
#endif
vtkSmartPointer<vtkActor> boundaryActor =
vtkSmartPointer<vtkActor>::New();
boundaryActor->SetMapper(boundaryMapper);
boundaryActor->GetProperty()->SetColor(1,0,0);
// Create a renderer, render window, and interactor
vtkSmartPointer<vtkRenderer> renderer =
vtkSmartPointer<vtkRenderer>::New();
vtkSmartPointer<vtkRenderWindow> renderWindow =
vtkSmartPointer<vtkRenderWindow>::New();
renderWindow->AddRenderer(renderer);
vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
vtkSmartPointer<vtkRenderWindowInteractor>::New();
renderWindowInteractor->SetRenderWindow(renderWindow);
// Add the actor to the scene
renderer->AddActor(meshActor);
renderer->AddActor(boundaryActor);
renderer->SetBackground(.3, .6, .3); // Background color green
// Render and interact
renderWindow->Render();
renderWindowInteractor->Start();
return EXIT_SUCCESS;
}
CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
PROJECT(ConstrainedDelaunay2D)
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})
add_executable(ConstrainedDelaunay2D MACOSX_BUNDLE ConstrainedDelaunay2D.cxx)
target_link_libraries(ConstrainedDelaunay2D ${VTK_LIBRARIES})
Download and Build ConstrainedDelaunay2D
Click here to download ConstrainedDelaunay2D and its CMakeLists.txt file. Once the tarball ConstrainedDelaunay2D.tar has been downloaded and extracted,
cd ConstrainedDelaunay2D/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:
./ConstrainedDelaunay2D
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.