[vtkusers] update scalars of vtkPoints

[Barth, Sebastian]

Hi Hagen,

did you also try scalars->Modified() instead?

With Modified() you tell the pipeline that the data object has to be updated (also everything coming after this object in pipeline). You might forgot to run Update() on your mapper the vtkUnstructedGrid is attached to (or any other object that has Update() and is connected after the grid in pipeline row). You might also forgot to call the Render() method to update the renderer?

Hope this helps!

Sebastian Barth

-----Ursprüngliche Nachricht-----
Von: Hagen Mölle [mailto:h.moelle at googlemail.com] 
Gesendet: Donnerstag, 1. Juli 2010 14:16
An: Barth, Sebastian
Cc: John Drescher; vtkusers at vtk.org; sebastien.jourdain at kitware.com
Betreff: Re: AW: [vtkusers] update scalars of vtkPoints

Hi Sebastian,

Thanks for your help. I got it working with vtkPolyData in my 2D 
visualization.

In my 3D visualization of measured points I still have the problem that 
the scalars do not change. There I use vtkUnstructuredGrid instead of 
vtkPolyData. Right now the update routine of the scalars looks like this 
(pseudo code):

scalars = vtkDataSet->GetPointData()->GetScalars()
for(number of scalars)
{
     update each scalar
}
vtkDataSet->Modified()

The code is compiling for vtkUnstructuredGrid and vtkPolyData. But it 
seems I have to do something additional to update the scalars of the 
vtkUnstructuredGrid.

Any idea?

Hagen


> Hello Hagen,
>
> did you forget to call Modified() of the vtkPolyData after altering the points? Otherwise the vtkPolyData does not know that their points, scalars or cells were changed.
>
> Sebastian Barth
>
> -----Ursprüngliche Nachricht-----
> Von: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] Im Auftrag von Hagen Mölle
> Gesendet: Donnerstag, 1. Juli 2010 08:26
> An: John Drescher; vtkusers at vtk.org; sebastien.jourdain at kitware.com
> Betreff: Re: [vtkusers] update scalars of vtkPoints
>
> On 06/30/2010 06:14 PM, John Drescher wrote:
>    
>> 2010/6/30 Sebastien Jourdain<sebastien.jourdain at kitware.com>:
>>
>>      
>>> Hi Hagen,
>>>
>>> As you said, you can start by simply change the data on the fly and
>>> call Render() once the change has been done. By change I mean point
>>> location, scalar data and even point number.
>>> But be aware that only one thread should be used in VTK otherwise they
>>> have to be synchronized.
>>>
>>>
>>>        
>> I think vtkPolyData->GetPointData->GetScalars()
>>
>> is where to start
>>
>> John
>>
>>      
> Hi Sebastien and John,
>
> Thanks for pointing out how to change the scalars of the points on the
> fly. So I need to alter the vtkDataArray which I get by
> vtkPolyData->GetPointData->GetScalars(). Hopefully this will work.
>
> Yesterday I tried to set new scalars by using the following method:
> vtkPolyData->GetPointData->SetScalars(vtkDoubleArray). So I did not
> generate a new dataset. But the visualization did not change during
> update. It seemed the old scalars where used during update.
>
> Hagen
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