[vtkusers] Creating a polygon from a closed polyline !

[Sebastien Auclair]

Thanks !
My problem was that i was trying to tessalate from vtkPolyLine instead of
vtkPolygon !

And the vtkPoints that are used can contain holes (i.e. Multiple polylines)
For that, i currently use vtkGLUTesselatorTriangleFilter.

It works fine now !

Thanks all !
________________________________________
Seb


----- Original Message -----
From: "Goodwin Lawlor" <goodwin.lawlor at ucd.ie>
To: "'Sebastien Auclair'" <sxa at fluent.com>; <vtkusers at public.kitware.com>
Sent: Thursday, February 13, 2003 11:38 AM
Subject: RE: [vtkusers] Creating a polygon from a closed polyline !


>
> Here's an example of how to do it from /Graphics/testing/tcl/capCow.tcl
>
> # Create polygons outlining clipped areas and triangulate them to
> generate cut surface
> vtkCutter cutEdges; #Generate cut lines
>   cutEdges SetInput [cowNormals GetOutput]
>   cutEdges SetCutFunction plane
>   cutEdges GenerateCutScalarsOn
>   cutEdges SetValue 0 0.5
> vtkStripper cutStrips; #Forms loops (closed polylines) from cutter
>   cutStrips SetInput [cutEdges GetOutput]
>   cutStrips Update
> vtkPolyData cutPoly; #This trick defines polygons as polyline loop
>   cutPoly SetPoints [[cutStrips GetOutput] GetPoints]
>   cutPoly SetPolys [[cutStrips GetOutput] GetLines]
> vtkTriangleFilter cutTriangles; #Triangulates the polygons to create cut
> surface
>   cutTriangles SetInput cutPoly
> vtkPolyDataMapper cutMapper
>   cutMapper SetInput cutPoly
>   cutMapper SetInput [cutTriangles GetOutput]
> vtkActor cutActor
>   cutActor SetMapper cutMapper
>   eval [cutActor GetProperty] SetColor $peacock
> -----Original Message-----
> From: vtkusers-admin at public.kitware.com
> [mailto:vtkusers-admin at public.kitware.com] On Behalf Of Sébastien MARAUX
> Sent: 12 February 2003 10:46
> To: Sebastien Auclair; vtkusers at public.kitware.com
> Subject: Re: [vtkusers] Creating a polygon from a closed polyline !
>
>
> Hello,
>
> it is possible to do it via creation of new polygon cells in place of
> polylines ones, and calling tesselate on it.
>
> pseudo code :
>
> new vtkPolydata,
> new temp cell (contains polygon)
> newpolydata SetPoints(yourpolydata GetPoints)
> for all polyline cells{
>     reset temp Cell
>     for all points of this poly {
>         if first, store
>         add point id to cell
>     }
>     add first stored id (to close polygon)
>     add cell to your poly
> }
> newpolydata Tesselate
>
> I don't have the time to tell you more, sorry
>
> good luck
>
> Seb
>
> ----- Original Message -----
> From: "Sebastien Auclair" <sxa at fluent.com>
> To: <vtkusers at public.kitware.com>
> Sent: Tuesday, February 11, 2003 10:55 PM
> Subject: [vtkusers] Creating a polygon from a closed polyline !
>
>
> > Greetings !
> >
> > We need to generate a surface out of 2D closed polylines. Like if we
> > have a circle as a polyline and all the points have z = 0 (i.e. 2D
> > polyline), we need to generate a surface for this circle to be
> displayed
> > as a disk !
> > Of course, some of our polylines do not form easy convex polygones.
> > But
> they
> > are always composed with points with z = 0.
> >
> >
> > So far we've tried this without success :
> >
> > (the code before the next line was trivial so not pasted...)
> > ................................................
> >  int pointCount = points->GetNumberOfPoints ();  //  points is a valid
>
> > vtkPoints  int i;
> >
> >  vtkPolyLine* aPolyline = vtkPolyLine::New();
> > aPolyline->GetPointIds()->SetNumberOfIds(pointCount);
> >  for (i = 0; i <  pointCount; i++){
> >         aPolyline->GetPointIds()->SetId( i, i);
> >  }
> >
> >  vtkUnstructuredGrid* aGrid = vtkUnstructuredGrid::New();
> > aGrid->Allocate(1,1 );  aGrid->InsertNextCell
> > (aPolyline->GetCellType(),
> > aPolyline->GetPointIds());
> >  aGrid->SetPoints( points->m_points);
> >  aGrid->Update();
> >
> >  vtkGeometryFilter* filter = vtkGeometryFilter::New();
> > filter->SetInput(aGrid);  filter->Update();
> >
> >
> >  vtkTriangleFilter* tri = vtkTriangleFilter::New();
> > tri->SetInput(filter->GetOutput());
> >  tri->Update();
> >  vtkStripper* strip = vtkStripper::New();
> > strip->SetInput(tri->GetOutput());
> >  strip->Update();
> > ...........................................................
> > The rest of the code is trivial !
> >
> >
> > Any suggestions ?
> >
> > Thanks
> >
> > _______________________________________________
> > Seb
> >
> > _______________________________________________
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> > Please keep messages on-topic. Check the FAQ at:
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> >
>
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