[vtkusers] How to construct polygon?

[rakesh patil]

Hi,

Well, I would like to know how polygon loop being non-planar leads to such
output. Because, the image shown in expectedOutput is also built of similar
polygon loop. Its just that for few curved surfaces are rendered properly
and few don't. I just want to know why is there such inconsistent behavior
and how do I overcome this?

Thanks

On Sat, Apr 15, 2017 at 10:56 AM, kenichiro yoshimi <rccm.kyoshimi at gmail.com
> wrote:

> Hi,
>
> Your polygon loop is non-planar.
>
> ​
> Howerver, the triangulate method used by vtkPolygon assumes that polygon
> points lie in a plane. I recommend to use vtkCylinderSource or
> vtkStructuredGrid to represent the side of surface of a cylinder.
>
> Thanks,
> yoshimi
>
> 2017-04-14 0:38 GMT+09:00 Rakesh Patil <rakesh.p at tataelxsi.co.in>:
>
>> Hi,
>>
>>
>> This question seems to be simple, but I am not able to get any output for
>> this. I am not able to understand what is happening in this case:
>>
>>
>> vtkSmartPointer<vtkPoints> tpoints = vtkSmartPointer<vtkPoints>::New();
>>
>> vtkSmartPointer<vtkPolygon> poly = vtkSmartPointer<vtkPolygon>::New();
>>
>> vtkSmartPointer<vtkCellArray> carr = vtkSmartPointer<vtkCellArray>::New();
>>
>> vtkSmartPointer<vtkPolyData> polyData = vtkSmartPointer<vtkPolyData>::New();
>>
>>
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( 4.39116, -2.39117, 4.5));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( 4.39116, -2.39117, 3));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( 4.39116, -2.39117, 1.5));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( 4.39116, -2.39117, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( 4.08748, -2.87967, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( 3.05391, -3.95899, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( 1.74755, -4.68466, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( 0.28509, -4.99187, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -1.20284, -4.85316, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -2.58332, -4.28094, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -3.73305, -3.32631, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -4.54931, -2.07456, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -4.95919, -0.637487, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -4.92609, 0.856528, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -4.45295, 2.27403, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -3.58205, 3.4884, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -2.39117, 4.39116, 0));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -2.39117, 4.39116, 1.5));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -2.39117, 4.39116, 3));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -2.39117, 4.39116, 4.5));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -2.39117, 4.39116, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -3.58205, 3.4884, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -4.45295, 2.27403, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint( -4.92609, 0.856528, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint(-4.95919, -0.637487, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint(-4.54931, -2.07456, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint(-3.73305, -3.32631, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint(-2.58332, -4.28094, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint(-1.20284, -4.85316, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint(0.28509, -4.99187, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint(1.74755, -4.68466, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint(3.05391, -3.95899, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint(4.08748, -2.87967, 6));
>>
>> poly->GetPointIds()->InsertNextId(tpoints->InsertNextPoint(4.39116, -2.39117, 6));
>>
>> carr->InsertNextCell(poly);
>>
>>
>>     polyData->SetPoints(tpoints);
>>
>>     polyData->SetPolys(carr);
>>
>>
>>     vtkSmartPointer<vtkTriangleFilter> tfilter = vtkSmartPointer<vtkTriangleFilter>::New();
>>
>>     tfilter->SetInputData(polyData);
>>
>>     tfilter->Update();
>>
>>
>>
>>     vtkSmartPointer<vtkPolyDataMapper> pmapper = vtkSmartPointer<vtkPolyDataMapper>::New();
>>
>>     pmapper->SetInputConnection(tfilter->GetOutputPort());
>>
>>
>>     vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
>>
>>     actor->SetMapper(pmapper);
>>
>>     actor->GetProperty()->SetRepresentationToSurface();
>>
>>     actor->GetProperty()->EdgeVisibilityOn();
>>
>>     actor->GetProperty()->SetEdgeColor(1.0, 0.0, 0.0);
>>
>>
>>     renderer->AddActor(actor);
>>
>>     renderer->ResetCamera();
>>
>>
>>
>> I am not able to view the output if I use vtkTriangleFilter. I have
>> attached two screenshots. One is to show how the expected output should
>> come. Another is the vtk's output without applying vtkTriangleFilter. How
>> do I get the curved surfaces based on the above geometry (points)?
>>
>>
>> Am I missing anything there?
>>
>>
>>
>> Thanks & Regards
>>
>> Rakesh Patil
>>
>>
>>
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> 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
>>
>> Search the list archives at: http://markmail.org/search/?q=vtkusers
>>
>> Follow this link to subscribe/unsubscribe:
>> http://public.kitware.com/mailman/listinfo/vtkusers
>>
>>
>
> _______________________________________________
> Powered by www.kitware.com
>
> 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
>
> Search the list archives at: http://markmail.org/search/?q=vtkusers
>
> Follow this link to subscribe/unsubscribe:
> http://public.kitware.com/mailman/listinfo/vtkusers
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20170417/7949133f/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: non_planar_polygon.png
Type: image/png
Size: 92659 bytes
Desc: not available
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20170417/7949133f/attachment.png>