Dear all

I want to construct a delaunay triangulation like:
<img src="http://vtk.1045678.n5.nabble.com/file/n5734051/1.jpg" border="0"/>

And I refer to the example: http://www.vtk.org/Wiki/VTK/Examples/Cxx/Filtering/ConstrainedDelaunay2D

But the result I get is:
<img src="http://vtk.1045678.n5.nabble.com/file/n5734051/2.png" border="0"/>

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 <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>

#define PI 3.1415926

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);
        }
        }*/
        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<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();

        /*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<vtkPolyData> boundary =
                vtkSmartPointer<vtkPolyData>::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<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;
}

   Thanks in advance !

ZhangQiang

        
        
        
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