[vtkusers] Get/Set values Vector Data

[Allen Sanderson]

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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