[vtkusers] trying to clip a polyData with an other

[David.Pont at ForestResearch.co.nz]

Hi Laurent,
   There is no way in vtk to clip one polydata with another.
vtkClipPolyData evaluates an implicit function at each point position in
the polydata and then clips each cell according to the implicit function
value at its points. So you can only clip with implicit surfaces. (Actually
you can also clip using scalar values associated with the polydata.) So
clipping and cutting in vtk is only done with implicit surfaces. Check the
class doc for vtkImplicitFunction and see its descendants for the list of
possible 'shapes' you can clip with.
GetOutput and SetThetaResolution belong to vtkSuperquadricSource which
produces a polygonal surface, good to look at, but no use for clipping.
vtkSuperquadric is an implicit surface, difficult to look at, but just
right for clipping.

  hope that clarifies...
    Dave P



                                                                                                               
                      Laurent Mundeleer                                                                        
                      <lmundele at ulb.ac.        To:       David.Pont at ForestResearch.co.nz                       
                      be>                      cc:       vtk <vtkusers at vtk.org>                                
                      Sent by:                 Subject:  Re: [vtkusers] trying to clip a polyData with an      
                      vtkusers-admin at vt         other                                                          
                      k.org                                                                                    
                                                                                                               
                                                                                                               
                      09/03/2004 22:11                                                                         
                                                                                                               
                                                                                                               




Hi David,

thanks for your answer, the problem with vtkSuperquadric is that there's
no GetOutput(), SetThetaResolution(),...

Is there another way to do that?

Thanks

Laurent

David.Pont at ForestResearch.co.nz wrote:

>Laurent,
>   vtkImplicitDataSet uses the data set scalars to perform clipping, I am
>not sure what scalars (if any) are produced by vtkSuperqadricSource. But I
>see there is vtkSuperquadric which can be passed directly to
>vtkClipPolydata->SetClipFunction.
>
>   Dave P
>
>
>
>

>                      Laurent Mundeleer

>                      <lmundele at ulb.ac.        To:       vtk
<vtkusers at vtk.org>
>                      be>                      cc:

>                      Sent by:                 Subject:  [vtkusers] trying
to clip a polyData with an other
>                      vtkusers-admin at vt

>                      k.org

>

>

>                      08/03/2004 22:56

>

>

>
>
>
>
>Hi All,
>
>I'dl like to clip a vtkPolyData with another one.
>Here's my code, based on the examples:
>
>---------------------
>
>vtkImplicitDataSet *v = vtkImplicitDataSet::New();
>v->SetDataSet(ovoideSample->GetInput()); // ovoideSample has on input a
>vtkSuperquadricSource
>
>vtkClipPolyData *clipper = vtkClipPolyData::New();
>clipper->SetInput(tumorSample->GetInput()); // tumorSample has on input
>a vtkSphereSource
>
>clipper->SetClipFunction(v);
>clipper->GenerateClipScalarsOn();
>clipper->Update();
>
>tumorSample->SetInput(clipper->GetOutput());
>aff->ChargerModel3D(tumorSample);
>
>---------------------
>
>but after that my tumorSample is empty.
>What do i wrong?
>
>Thanks in advance,
>Regards
>
>Laurent
>
>
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--
********************************************
Laurent Mundeleer
Université Libre de Bruxelles (ULB)
Service des Systèmes Logiques et Numériques (SLN) CP165/57
50, Av. F.Roosevelt
1050 Bruxelles
Belgium
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