[vtkusers] vtkDelauany2D triangulation--But where are the triangles????

[Dhaniram Kshirsagar]

Hi Sylvain,
 That worked for me... thanks :)
 One change is required in following code:
change:
*vtkPolyData* outMesh = delaunay2D->GetOutPut( );*
*delaunay2D*->GetPolys()->InitTraversal();

while ( d*elaunay2D*->GetPolys()->GetNextCell( npts, pts ) )
{
cout << "points in the triangle: " << pts[0] << " " << pts[1] << " "
<< pts[2] << "\n";
}
 Instead of delaunay2D ptr here the ptr of polydata which is output from
triangulation should be used.
 thanks
dhani
 2005/11/7, Sylvain Jaume <sylvain.jaume at kitware.com>:
>
> Hi Dhaniram Kshirsagar,
>
> vtkDelaunay2D takes points at its input, and gives triangles at its ouput.
> Read http://www.vtk.org/doc/nightly/html/classvtkDelaunay2D.html
> More information in the VTK book:
> http://www.kitware.com/products/vtktextbook.html
>
> You may find this code snippet useful:
>
> vtkPoints *newPoints = vtkPoints::New();
> newPoints->InsertNextPoint( 0, 0, 0 );
> newPoints->InsertNextPoint( 1, 0, 0 );
> // create more points
>
> vtkPolyData *polyData = vtkPolyData::New();
> polyData->SetPoints( newPoints );
> newPoints->Delete();
>
> vtkDelaunay2D *delaunay2D = vtkDelaunay2D::New();
> delaunay2D->SetInput( polyData );
> polyData->Delete();
> delaunay2D->Update();
>
> int npts, *pts;
>
> delaunay2D->GetPolys()->InitTraversal();
>
> while ( delaunay2D->GetPolys()->GetNextCell( npts, pts ) )
> {
> cout << "points in the triangle: " << pts[0] << " " << pts[1] << " "
> << pts[2] << "\n";
> }
>
> Cheers,
> Sylvain
>
> Dhaniram Kshirsagar wrote:
>
> > Hi Sylvain,
> >
> > ---->>>>>Do you mean that you get the input triangles at the output?
> > Yes I made some sequential polys like this...
> >
> > int numPts = Points->GetNumberOfPoints();
> > for( int idx=0; idx< numPts; )
> > {
> > int nPoly[3];
> > nPoly[0] = idx;
> > nPoly[1] = ++idx;
> > nPoly[2] = ++idx;
> > *vtkPolys*->InsertNextCell( 3, nPoly );
> > }
> >
> > *vtkPolys --> input to vtkPolyData which already contains the
> vtkPoints.*
> > **
> > ---->>>>>You do not need to set the polys.
> >
> > You mean to say I need to input *only points*
> > (vtkPoints->vtkPolyData->vtkDelaunay2D)?
> > and i will get the triangles at output? no cellarray for polys?
> >
> > If yes please let me know the code snippet for the same which will
> > take points and will result in polys(triangles).
> >
> > Thanks for the reply.
> >
> > Thankx
> >
> >
> > 2005/11/5, Sylvain Jaume <sylvain.jaume at kitware.com
> > <mailto:sylvain.jaume at kitware.com>>:
> >
> > Hi Dhaniram Kshirsagar,
> >
> > Do you mean that you get the input triangles at the output?
> > You do not need to set the polys.
> >
> > Cheers,
> > Sylvain
> >
> > Dhaniram Kshirsagar wrote:
> >
> > > Hi Sylvain,
> > >
> > > After setting the vtkcellarray(for polys) in vtkpolydata (which is
> > > input to the delaunay2d), Now I am able to get the triangles.
> > >
> > > Thankx
> > >
> > >
> > > 2005/11/4, Sylvain Jaume <sylvain.jaume at kitware.com
> > <mailto:sylvain.jaume at kitware.com>
> > > <mailto:sylvain.jaume at kitware.com
> > <mailto:sylvain.jaume at kitware.com>>>:
> > >
> > > Hi Dhaniram Kshirsagar,
> > >
> > > You don't need to use delaunay->SetSource().
> > > Use it only if you want constrained Delaunay.
> > >
> > > Cheers,
> > > Sylvain
> > >
> > > Dhaniram Kshirsagar wrote:
> > >
> > > > Hi,
> > > >
> > > > I searched the entire mail archive for answer to my
> > problem, but
> > > found
> > > > only problems no solutions to them.
> > > >
> > > > My problem is, I have input points in the form of x, y and
> > z (large
> > > > numbers(double type)) and i want the output as the set of
> > triangles,
> > > > however i am getting only the
> > > > vertics.
> > > >
> > > > Here is the code snippet that i am using to get the output
> > as set of
> > > > triangles.
> > > >
> > > > vtkDelaunay2D* pDelny = vtkDelaunay2D::New( );
> > > > vtkPolyData* pPointSet = vtkPolyData::New( );
> > > > vtkPoints* pPoints = vtkPoints::New( );
> > > >
> > > > //collects the points i.e. x , y, and z
> > > > GetPoints( pPoints );
> > > >
> > > > pPointSet->SetPoints( pPoints );
> > > >
> > > > //now generate the vtk file
> > > > vtkPolyDataWriter* writer = vtkPolyDataWriter::New();
> > > > writer->SetFileName( "c:\\earth.vtk");
> > > > writer->SetInput( pPointSet );
> > > > writer->Write(); //throws an exception
> > > > writer->Update();
> > > > * /***the generated vtk file contains the
> > only one
> > > fixed
> > > > value***/
> > > > ///However i am not usig this file
> > > > *
> > > > pDelny->SetTolerance( 0.001 );
> > > > //pDelny->SetBoundingTriangulation(1);
> > > > pDelny->SetAlpha( 1 );
> > > > //pDelny->BoundingTriangulationOff();
> > > > //pDelny->SetOffset( 1000 );
> > > >
> > > > pDelny->SetInput(pPointSet);
> > > > pDelny->SetSource( pPointSet );
> > > > pDelny->Update();
> > > >
> > > >
> > > > vtkPolyData* pVtkData = pDelny->GetOutput( );
> > > > int nsize = pVtkData->GetNumberOfCells(); //returned the
> > same
> > > number
> > > > as the number of points
> > > > vtkCellArray* cellPol = pVtkData->GetPolys(); //zero returned
> > > > int numpol = cellPol->GetNumberOfCells();
> > > > vtkCellArray* cellVert = pVtkData->GetVerts();
> > > > int numver = cellVert->GetNumberOfCells(); //returned the
> > same
> > > number
> > > > as the number of points
> > > >
> > > > nCells = pVtkData->GetNumberOfPolys();
> > > > nCnt3 = pVtkData->GetNumberOfVerts(); //returned the same
> > number as
> > > > the number of points
> > > >
> > > > But where are the triangles????
> > > >
> > > > Now through pDelny->GetOutput I am expecting set of
> > triangles in
> > > > vtkPolyData object.
> > > > Am I right?
> > > >
> > > > Thanks
> > > >
> > >
> >
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