# [vtkusers] A problem with ConstrainedDelaunay2D

zhq 15891495523 at 126.com
Tue Sep 22 10:43:01 EDT 2015

```Dear allI want to construct a delaunay triangulation like:
<http://vtk.1045678.n5.nabble.com/file/n5734051/1.jpg> And I refer to the
example:
http://www.vtk.org/Wiki/VTK/Examples/Cxx/Filtering/ConstrainedDelaunay2DBut
the result I get is: <http://vtk.1045678.n5.nabble.com/file/n5734051/2.png>
How to deal with the triangulation in the inner circle ? Maybe I should set
a good boundary. But I don't know how to set the boundary. It's still not
correct if I set the inner circle as the boundary.My code is :#include
#include #include #include #include #include #include #include #include
#include #include #include #include #include #define PI 3.1415926int
main(int, char *[]){	// Generate a 10 x 10 grid of points	vtkSmartPointer
points =		vtkSmartPointer::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);	}	}*/	for
(int theta = 0;theta<360;theta++)	{		double x = 2*cos(theta*PI/180);		double
y = 2*sin(theta*PI/180);		points->InsertNextPoint(x,y,0);	}	for (int theta =
0;theta<360;theta++)	{		double x = cos(theta*PI/180);		double y =
sin(theta*PI/180);		points->InsertNextPoint(x,y,0);	}	vtkSmartPointer
aPolyData =		vtkSmartPointer::New();	aPolyData->SetPoints(points);	// Create
a cell array to store the polygon in	vtkSmartPointer aCellArray =
vtkSmartPointer::New();	// Define a polygonal hole with a clockwise polygon
vtkSmartPointer aPolygon =		vtkSmartPointer::New();	/*for (int
i=0;i<360;i++)	{		aPolygon->GetPointIds()->InsertNextId(i+360);	}*/	double
x[3];	/*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 boundary =		vtkSmartPointer::New();
boundary->SetPoints(aPolyData->GetPoints());	boundary->SetPolys(aCellArray);
boundary->GetPoint(1,x);	int n = boundary->GetPoints()->GetNumberOfPoints();
for (int i=0;i<n;i++)	{		boundary->GetPoint(i,x);	}	// Triangulate the grid
points	vtkSmartPointer delaunay =		vtkSmartPointer::New();#if
VTK_MAJOR_VERSION <= 5	delaunay->SetInput(aPolyData);
delaunay->SetSource(boundary);#else	delaunay->SetInputData(aPolyData);
delaunay->SetSourceData(boundary);#endif	delaunay->Update();	// Visualize
vtkSmartPointer meshMapper =		vtkSmartPointer::New();
meshMapper->SetInputConnection(delaunay->GetOutputPort());	vtkSmartPointer
meshActor =		vtkSmartPointer::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
boundaryMapper =		vtkSmartPointer::New();#if VTK_MAJOR_VERSION <= 5
boundaryMapper->SetInputConnection(boundary->GetProducerPort());#else
boundaryMapper->SetInputData(boundary);#endif	vtkSmartPointer boundaryActor
=		vtkSmartPointer::New();	boundaryActor->SetMapper(boundaryMapper);
boundaryActor->GetProperty()->SetColor(1,0,0);	// Create a renderer, render
window, and interactor	vtkSmartPointer renderer =		vtkSmartPointer::New();
vtkSmartPointer renderWindow =		vtkSmartPointer::New();
=		vtkSmartPointer::New();
renderWindowInteractor->SetRenderWindow(renderWindow);	// Add the actor to
renderer->SetBackground(.3, .6, .3); // Background color green	// Render and
interact	renderWindow->Render();	renderWindowInteractor->Start();	return