[vtkusers] How to construct polygon?

Wed Apr 19 22:26:08 EDT 2017

Hi Rakesh,

No, it will not work. It is difficult for my way to be extended to the
generic cases. I'm afraid I have no idea in VTK.

Thanks,
yoshimi

2017-04-19 22:06 GMT+09:00 rakesh patil <prakeshofficial at gmail.com>:

> Hi Yoshimi,
>
> I tried your sample code. It works for that set of input. Is it possible
> to make it a generic algorithm? Like for any given set of inputs, will it
> work?
>
> Thanks & Regards
>
> On Tue, Apr 18, 2017 at 12:07 PM, rakesh patil <prakeshofficial at gmail.com>
> wrote:
>
>> Hi Andrew,
>>
>> I am trying to visualise a BRep object using VTK. I get the lines that
>> forms a closed face. I create a vtkPolyData of each face and append it
>> using vtkAppendPolyData. So the purpose is to visualise this BRep object as
>> a wireframe as well as a surface. Seems that polygon rendering is not
>> happening properly.
>>
>> I am able to connect those lines in sequence, to form a connected closed
>> polygon. I face this problem only for the curved surface. For planar
>> surfaces I don't see any issue. The data set shown in my sample code, is
>> just one particular case. And for that case, Yoshimi's logic gives good
>> surface representation. But I am not sure how far it will work for all the
>> cases, I am in process to make it a generic one.
>>
>> Your inputs are welcome.
>>
>> Thanks & Regards
>> Rakesh Patil
>>
>> On Tue, Apr 18, 2017 at 11:56 AM, Andrew Maclean <
>> andrew.amaclean at gmail.com> wrote:
>>
>>> Hi Rakesh,
>>>    I don't know what you intend to use it for. However if it is just a
>>> one-off construction another suggestion would be to manually triangulate
>>> the surface yourself.
>>>
>>> This is what is done for the VTK Parametric Functions.
>>>
>>> See void vtkParametricFunctionSource::MakeTriangles() and void
>>> AddTriCells() in vtkParametricFunctionSource.cxx.
>>>
>>> Andrew
>>>
>>>
>>>
>>>> ---------- Forwarded message ----------
>>>> From: rakesh patil <prakeshofficial at gmail.com>
>>>> To: kenichiro yoshimi <rccm.kyoshimi at gmail.com>
>>>> Cc: "vtkusers at vtk.org" <vtkusers at vtk.org>
>>>> Bcc:
>>>> Date: Mon, 17 Apr 2017 09:58:08 +0530
>>>> Subject: Re: [vtkusers] How to construct polygon?
>>>> Hi,
>>>>
>>>> I thought that vtkTriangleFilter does the tessellation of polygon by
>>>> triangulating. Correct me if I am wrong. Let me try your suggestion and
>>>> come back.
>>>>
>>>> Thanks
>>>>
>>>> On Mon, Apr 17, 2017 at 7:34 AM, kenichiro yoshimi <
>>>> rccm.kyoshimi at gmail.com> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> It looks like the issue of rendering concave polygons by OpenGL
>>>>> included in the past mailing list, and it is concluded that OpenGL doesn't
>>>>> render concave polygons properly and needs tessellation:
>>>>> http://public.kitware.com/pipermail/vtkusers/2010-May/059784.html
>>>>> http://vtk.1045678.n5.nabble.com/problems-rendering-concave-
>>>>> polygon-td5007789.html
>>>>> (I'm sorry I don't know the details of this problem.)
>>>>>
>>>>> I suggest using vtkDelaunay3D for tessellating and then using
>>>>> vtkGeometryFilter that extracts the external faces.
>>>>>
>>>>> Thanks,
>>>>> yoshimi
>>>>>
>>>>> 2017-04-17 3:30 GMT+09:00 rakesh patil <prakeshofficial at gmail.com>:
>>>>>
>>>>>> 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
>>>>>>>>
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>>>>>>>>
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>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> 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
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>>
>>> --
>>> ___________________________________________
>>> Andrew J. P. Maclean
>>>
>>> ___________________________________________
>>>
>>
>>
>
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