[vtkusers] Get/Set values Vector Data

[Chiranjib Sur]

Hi Allen,
Thanks for your reply. I now understand the philosophy behind the insert
tuple thing.
One the other hand, to reply your questions (if I understood it correctly),
I can do the get/set operation with scalars (single component) easily and
correctly, which means my polydata points are created properly. What
exactly you mean by "down stream".

I am new to this field and may be I am missing the terminologies. To
reiterate, my problem is to assign same vector properties to my poly points
but with different values (separated by offset).

Thanks again in advance for your help.

Chiranjib

On Wed, Mar 18, 2015 at 9:49 PM, Allen Sanderson <allen at sci.utah.edu> wrote:

> You do not need to do an insert next tuple as memory has already been
> allocated with the call to SetNumberOfTuples.
>
> Right off I do see anything wrong with your approach. I would check the
> obvious does your polydata have points?? What happens to it down stream??
>
>
> Cheers,
>
> Allen
>
>
>
>
> On Mar 18, 2015, at 12:55 PM, Chiranjib Sur <sur.chiranjib at gmail.com>
> wrote:
>
> HI Allen,
> Thanks for the pointer. I am having some issues with this. before
> explaining the issues let me state the problem I am trying to solve in bit
> more dtails.
>
> I have a poly data which corresponds to to different set, i.e. the
> combined poly data I am dealing with correspond to two different section of
> the geometrical object. And I know the offset of the data set which
> differentiates object A from Object B from the polydata.
>
> Now when I am trying to set value like velocity with 3 component, I am
> facing the issues. Although I do the following, the properties are getting
> assigned randomly. Here is the snippet of my code :
>
>
> vtkSmartPointer<vtkDoubleArray> velocity =
> vtkSmartPointer<vtkDoubleArray>::New();
> velocity->SetName ("Velocity");
> velocity->SetNumberOfComponents(3);
>
> velocity->SetNumberOfTuples( polydata->GetNumberOfPoints());
>
> polydata->GetPointData()->AddArray( velocity );
>
>    for (long long i = offset; i < polydata->GetNumberOfPoints(); ++i)
>  // offset determines the position of the polydata I want to start with
> instead of starting at == 0)
>    {
>    velocity->SetTuple3( i,  _Vx, _Vy, _Vz );            //_Vx,_Vy,_Vz are
> double and declared elsewhere
>    //      velocity->InsertNextTuple3(  _Vx, _Vy, _Vz );       // Instead
> of using SetTuple3, I can use InsertNextTuple3 or InsertTuple3 too.
>    }
>
>
> Am I doing anything wrong here ?
>
> Thanks much,
> Chiranjib
>
> On Tue, Mar 17, 2015 at 6:55 PM, Allen Sanderson <allen at sci.utah.edu>
> wrote:
>
>> Here is some sample code:
>>
>> vtkDoubleArray *velocityArray = vtkDoubleArray::New();
>> velocityArray->SetName(var.c_str());
>> // NOTE: you want to set the number of components BEFORE setting the
>> number of Tuples so memory is correctly allocated.
>>
>> velocityArray->SetNumberOfComponents(3);
>> velocityArray->SetNumberOfTuples(nTuples);
>>
>> polydata->GetPointData()->AddArray(velocityArray);
>>
>> double dx, dy, dz;
>>
>> Loop: velocityArray->SetTuple3(index, dx, dy, dz);
>> Where : 0<= index < nTuples
>>
>> velocityArray->Delete();
>>
>>
>> The get would be:
>>
>> double *velocity = velocityArray->GetTuple3(l);
>>
>>
>> Cheers,
>>
>> Allen
>>
>>
>> Allen Sanderson
>> SCI Institute
>> University of Utah
>> www.sci.utah.edu
>>
>>
>>
>> On Mar 17, 2015, at 1:03 PM, Chiranjib Sur <sur.chiranjib at gmail.com>
>> wrote:
>>
>> Hi All,
>> I want to assign values (3 component vector) to all in a polydata set.
>> I found the email thread where the solution for a one component scalar
>> data is explained (
>> http://vtk.1045678.n5.nabble.com/Get-Set-values-in-scalar-data-td3259506.html
>> )
>>
>> Anybody can help explaining how to do this for a 3-component vector data
>> type.
>>
>> Thanks in advance.
>>
>> Chiranjib Sur
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