[vtkusers] Problem with color after using vtkClipPolyData

[David Gobbi]

Clipping a data set adds scalars to the data set. By default, if a
data set has scalars, then VTK mapper uses the scalars to color
the data.  Just do the following:

mapper->ScalarVisibilityOff();

Then VTK will ignore the scalars and use the vtkProperty color
instead.

 - David


On Fri, Dec 14, 2012 at 6:28 AM, Gerrick Bivins
<Gerrick.Bivins at halliburton.com> wrote:
> I had a similar issue and ended up abandoning vtkClipPolyData and instead clipping the source with vtkClipDataSet.
> http://www.vtk.org/pipermail/vtkusers/2008-July/096200.html
>
> This was a while ago and I seem to remember digging through vtkClipPolyData source to find the problem but to no avail.
> I think there is a bug but having made things work with vtkClipDataSet, I moved on.
> Gerrick
>
> -----Original Message-----
> From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On Behalf Of Alex Malyushytskyy
> Sent: Thursday, December 13, 2012 7:50 PM
> To: vtkusers
> Subject: Re: [vtkusers] Problem with color after using vtkClipPolyData
>
> It is difficult to say without looking in the data and code.
> Normal  for example can change color significant due to possible change which side of polygon is counted as inner surface.
>
> But it might be hundred of other reasons and I am not sure I can list all.
>
> Alex
>
> On Wed, Dec 12, 2012 at 5:54 PM, gongweixue <gongweixue at sina.com> wrote:
>> Thanks for your answer.
>> Yes, I also have tried to clip polydata, not normals.
>> But the result's color is just not same as the original model.
>> So I think maybe it is my model's problem,because the model is
>> converted from a vrml model.
>> I used vtkTableBasedClipDataSet, and the color is right. I was confused.
>> And when treat it as a DataSet with normals, the color is right.
>> Do you know the reason?
>>
>> Thank you very much!
>> 2012/12/13
>> gongweixue at sina.com
>>
>> ----- Original Message -----
>> From: Alex Malyushytskyy
>> To: vtkusers
>> Date: 2012-12-13, 07:34:12
>> Subject: Re: [vtkusers] Problem with color after using vtkClipPolyData
>>
>> Self-sufficient example would help.
>> As is I can only guess that you probably did not want to clip normal
>> as you currently do and wanted to clip read polydata:
>>
>>  clipper->SetInput(reader->GetOutput());
>>
>> Alex
>>
>> On Tue, Dec 11, 2012 at 10:18 PM, gongweixue <gongweixue at sina.com> wrote:
>>> hi guys,
>>> I used a vtkClipPolyData to clip polydata, and I found that the color
>>> of surfaces after clipping is changed.
>>> So,dose anybody know the reason?
>>> here is my code.
>>>
>>> //////////////////////code/////////////////////////////
>>> vtkPolyDataReader *reader=vtkPolyDataReader::New();
>>> reader->SetFileName(FILENAME);
>>> reader->Update();
>>>
>>> vtkClipPolyData * clipper=vtkClipPolyData::New();
>>> clipper->SetInput(normals->GetOutput());
>>> vtkPlane * plane = vtkPlane::New();
>>> plane->SetOrigin(0.5,0,0);
>>> plane->SetNormal(1,1,1);
>>> clipper->SetClipFunction(plane);
>>> clipper->SetValue(0.5);
>>> clipper->SetInsideOut(1);
>>> clipper->Update();
>>>
>>> vtkPolyDataMapper *mapper=vtkPolyDataMapper::New();
>>> mapper->SetInput(clipper->GetOutput());
>>> vtkActor *actor=vtkActor::New();
>>> actor->SetMapper(mapper);
>>> vtkRenderer *ren1= vtkRenderer::New();
>>> ren1->AddActor( actor );
>>> ren1->SetBackground( 0.1, 0.2, 0.4 );
>>> vtkRenderWindow *renWin = vtkRenderWindow::New();
>>> renWin->AddRenderer( ren1 );
>>> renWin->SetSize( 600, 600 );
>>> vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
>>> iren->SetRenderWindow(renWin);
>>> vtkInteractorStyleTrackballCamera *style =
>>> vtkInteractorStyleTrackballCamera::New();
>>> iren->SetInteractorStyle(style);
>>> iren->Initialize();
>>> iren->Start();
>>> ///////////////////////////////////////////////
>>> And here is the pic:
>>> http://p13.freep.cn/p.aspx?u=v20_p13_photo_1212121410379520_0.jpg
>>>
>>> I will appreciate any suggestion very much!
>>>
>>>
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> _______________________________________________
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>
> Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ
>
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> Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html
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