[vtkusers] Removing internal cells !

[Sebastien Auclair]

This is the code :

######################################################################
/*
    THE CODE USUALLY PRESENT BEFORE THIS LINE IS NOT RELEVANT FOR THIS
MAILLED CODE SAMBLE
*/
 int h, i, pointCount, oldPointCount, polylineCount;
 vtkPolyData* aGrid = vtkPolyData::New();


 polylineCount = m_AllPolylines.count();

 QDictIterator<TK3DPointList> it( m_AllPolylines ); // See QDictIterator
 it.toFirst () ;
 aGrid->Allocate(polylineCount, polylineCount );
 oldPointCount = 0;

 vtkPoints* allPoints = vtkPoints::New();
 allPoints = getAllPolylinesPoints();
// This will put in allPoints the following points describing a square:
/*
 (0, 0.0 ,0.0, 0.0);
 (1,  20.0 ,0.0, 0.0);
 (2,  20.0 ,20.0, 0.0);
 (3,  0.0 ,20.0, 0.0);
 (4,  0.0 ,0.0, 0.0);

*/
 vtkIdList* array = vtkIdList::New();

 for (h = 0; h < polylineCount; h++){
      pointCount = (it.current())->m_points->GetNumberOfPoints ();

      array->SetNumberOfIds(pointCount);
      for (i = 0; i <  pointCount; i++){
           array->SetId(i, i + oldPointCount);
      }
      aGrid->InsertNextCell (VTK_POLYGON,  array);
      array->Reset();
      oldPointCount += pointCount;
      ++it ;
 }

 aGrid->SetPoints( allPoints);
 aGrid->Update();

 vtkGLUTesselatorTriangleFilter* tri =
vtkGLUTesselatorTriangleFilter::New();
 tri->SetInput(aGrid);
 tri->PassVertsOff ();
 tri->PassLinesOff ();
 tri->Update();

 vtkReverseSense* reverser = vtkReverseSense::New();
 reverser->SetInput(tri->GetOutput());
 reverser->ReverseCellsOn ();
 reverser->ReverseNormalsOff ();
 reverser->Update();

 vtkPolyDataNormals* normalA = vtkPolyDataNormals::New();
 normalA->SetInput(reverser->GetOutput());
 normalA->Update();


 vtkLinearExtrusionFilter* extruder= vtkLinearExtrusionFilter::New();
 extruder->SetInput(normalA->GetOutput());
 extruder->SetExtrusionTypeToNormalExtrusion ();
 extruder->CappingOn ();
 extruder->SetScaleFactor (-m_thickness);
 extruder->Update();

 vtkPolyDataNormals* normal = vtkPolyDataNormals::New();
 normal->SetInput(extruder->GetOutput());
 normal->Update();

/*
    THE CODE USUALLY HERE IS NOT RELEVANT FOR THIS MAILLED CODE SAMBLE
*/


 aGrid->Delete();
 array->Delete();
 tri->Delete();
 reverser->Delete();
 normalA->Delete();
 normal->Delete();
 extruder->Delete();
 allPoints->Delete();
##################################################################3


Thanks !
__________________________________
Seb





----- Original Message -----
From: "Berk Geveci" <berklist at nycap.rr.com>
To: "Sebastien Auclair" <sxa at fluent.com>
Sent: Thursday, April 17, 2003 4:11 PM
Subject: Re: [vtkusers] Removing internal cells !


> > Yes i'am using vtkLinearExtrusionFilter.
> > The polygons are complex and often non-convex so before being extruded,
they
> > are passed through vtkGLUTesselatorTriangleFilter.
> >
> > When displayed with transparency, we can see the internal facets !
>
> hmm. I wonder if this has something to do with the way
> tesselation is done (duplicate points, edges etc.). Can you
> reproduce this with one simple polygon (and if you can,
> can you write it to a file and send it to me) ?
>
> -Berk
>
>
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