[vtkusers] some queries with vtkcellarrays

[Chiranjib Sur]

Hi Sankesh,
Thanks for the pointers. If I change this to the following



   for (vtkIdType i= 0; i < count; i++)
   {
       cell->InsertNextCell( i );
cell->InsertCellPoint(i);
   }
will this mean the same what you are suggesting? In that case how the
points are getting distributed ? I have been learning VTK by going through
the examples. Indeed they are useful.

I would really appreciate, if you can point me towards some "description"
of VTK cells / normals /Tcoords etc that will be very helpful to understand
the underlying concepts easily.

Thanks,
Chiranjib

On Tue, Jul 21, 2015 at 8:27 PM, Sankhesh Jhaveri <
sankhesh.jhaveri at kitware.com> wrote:

> Hi Chiranjib,
>
> Your code calls InsertNextCell once and adds all points to that cell using
> InsertCellPoint. Thats why you just end up with one cell.
>
> You can add more cells by calling InsertNextCell as many times as the
> number of cells you want. You will have to distribute the points in the
> resultant cells accordingly.
>
> Take a look at examples here: http://www.vtk.org/Wiki/VTK/Examples/Cxx
>
>
>
> Warm Regards,
>
> Sankhesh Jhaveri
> Research & Development Engineer
> Kitware, Inc.
> *Phone*: (518) 881 4417
> *Fax*: (518) 371 4573
>
>
>
> On Mon, Jul 20, 2015 at 5:48 AM, Chiranjib Sur <sur.chiranjib at gmail.com>
> wrote:
>
>> Hi VTK experts,
>> I am not an expert vtk programmers like many others in the forum. I have
>> a confusion.
>>
>> I am creating a set of vtk points (and eventually a vtkpolydata) and want
>> to create vtkcells for the associated points. I was looking at the examples
>> and trying to implement this way (
>> http://www.vtk.org/gitweb?p=VTK.git;a=blob;f=Examples/VisualizationAlgorithms/Cxx/TubesWithVaryingRadiusAndColors.cxx
>> )
>>
>> What I am observing is that when I create vtkcells, I only create ONE
>> cell. What is going wrong here and why not all vtkcells are created?
>>
>> Any suggestions ?
>>
>> Thanks in advance,
>> Chiranjib
>>
>> Here is my code snippet
>>
>>
>>
>> // VTK points are defined here
>>
>>     vtkSmartPointer<vtkPoints> newPoints =
>> vtkSmartPointer<vtkPoints>::New();
>>
>> // Set precision for the vtk points
>>    newPoints->SetDataType( VTK_DOUBLE );
>>
>>     unsigned int count = 0;
>>     double resolution = 0.1;
>>
>> // Create the points for the entire volume
>>       for (unsigned int j = 0; j<10; j++)
>>       {
>>          for (unsigned int i = 0; i<10; i++)
>>          {
>>             for (unsigned int k = 0; k<10; k++)
>>             {
>>                newPoints->InsertNextPoint( x0[0]+ resolution*i, x0[1]+
>> resolution*j, x0[2]+ resolution*k );
>>                count++;
>>             }
>>          }
>>       }
>>
>> std::cout << "length of mycube = " << xl << ","<<yl<<","<<zl << std::endl;
>> std::cout << "Number of points = " << count << std::endl;
>>
>>
>>
>>    // Insert vtk cell arrays
>>    vtkSmartPointer<vtkCellArray> cell =
>> vtkSmartPointer<vtkCellArray>::New();
>>
>>    cell->InsertNextCell( count);
>>
>>    for (vtkIdType i= 0; i < count; i++)
>>    {
>>    cell->InsertCellPoint(i);
>>    }
>>
>> // Define the polydata for the cube
>>       vtkSmartPointer<vtkPolyData> np =
>> vtkSmartPointer<vtkPolyData>::New();
>>       np->SetPoints( newPoints );
>>       np->SetLines( cell);
>>
>>    std::cout << "Number of cells "<< np->GetNumberOfCells() << ":" <<
>> count << std::endl;
>>
>>
>> _______________________________________________
>> 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/20150721/d2994e8f/attachment.html>