[Paraview-developers] How to implement an identity filter ?
Joachim Pouderoux
joachim.pouderoux at kitware.com
Sun Jul 19 15:25:51 EDT 2015
Franck,
What do you do in RequestData()? You are supposed to shallow copy input to
the output, right?
Joachim
*Joachim Pouderoux*
*PhD, Technical Expert*
*Kitware SAS <http://www.kitware.fr>*
2015-07-19 19:53 GMT+02:00 houssen <houssen at ipgp.fr>:
> Still get the zero filter ?!... Don't understand !? If somebody has an
> idea ?... Something to check ? Verify ? Track ? Something missing ? Add tag
> in xml ? Missing rendering call ?
>
> Now, I derive from vtkDataObjectAlgorithm, I re-implement only
> RequestDataObject. I tried without success to create a new instance (from
> pInputObj) to pass to pOutputInfo (with and without using DeepCopy) :
> finally I tried to pass directly pInputObj. In the GUI, in the information
> tab, I get the expected type but zero point / cell. When I delete the
> filter, the initial data are still here (tab info indicates non zero number
> of points / cells) but the 3D viewpoint is empty : can this be a clue of
> some problem ?
>
> Franck
>
> int myFilter::RequestDataObject ( vtkInformation * ipRequest,
> vtkInformationVector ** ipInputVector, vtkInformationVector *
> opOutputVector )
> {
> if ( !ipRequest ) return 0;
>
> vtkInformation * pInputInfo = ( ipInputVector ) ? ipInputVector[0] ->
> GetInformationObject ( 0 ) : NULL;
> vtkDataObject * pInputObj = ( pInputInfo ) ? pInputInfo ->
> Get ( vtkDataObject::DATA_OBJECT () ) : NULL;
> if ( pInputObj )
> {
> vtkInformation * pOutputInfo = ( opOutputVector ) ? opOutputVector ->
> GetInformationObject ( 0 ) : NULL;
> vtkDataObject * pOutputObj = ( pOutputInfo ) ? pOutputInfo ->
> Get ( vtkDataObject::DATA_OBJECT () ) : NULL;
> if ( !pOutputObj )
> {
> _OutputDataType = pInputObj -> GetClassName (); // For later call to
> FillOutputPortInformation
> pOutputInfo -> Set ( vtkDataObject::DATA_OBJECT (), pInputObj );
> return 1;
> }
> }
> return 0;
> }
>
> int myFilter::FillOutputPortInformation ( int iPort, vtkInformation *
> ipInfo )
> {
> if ( ipInfo ) ipInfo -> Set ( vtkDataObject::DATA_TYPE_NAME (),
> _OutputDataType.c_str () ); // Output data type to create (called after
> ProcessRequest)
> return 1;
> }
>
> Le 2015-07-15 23:49, houssen a écrit :
>
>> Shawn, Joachim, thanks.
>> After a quick look at the code, if I got you right, on a
>> REQUEST_DATA_OBJECT request, I still need to create a new instance of
>> the input and to set it as the DATA_OBJECT of the vtkInfo of the
>> output. I still have to test this, but, I got the idea !
>>
>> Franck
>>
>> Le 2015-07-15 15:47, Shawn Waldon a écrit :
>>
>>> You might want to take a look at inheriting from
>>> vtkPassInputTypeAlgorithm[1] if you want the output type to be the
>>> same as the input type. It already implements RequestDataObject the
>>> way that I think Joachim is suggesting.
>>>
>>> HTH,
>>> Shawn
>>>
>>> [1]:
>>>
>>> http://www.vtk.org/doc/nightly/html/classvtkPassInputTypeAlgorithm.html
>>> [14]
>>>
>>> On Wed, Jul 15, 2015 at 7:27 AM, Joachim Pouderoux
>>> <joachim.pouderoux at kitware.com [15]> wrote:
>>>
>>> Franck,
>>>>
>>>> You will have to override the RequestDataObject() method in order
>>>> to make your filter generic. This method is the one called to
>>>> generate the output data object.
>>>> Take a look at vtkGenerateIndexArray.cxx for instance, I think you
>>>> can just copy it in your class (which should be derivated from
>>>> vtkDataObjectAlgorithm).
>>>>
>>>> Best,
>>>>
>>>> JOACHIM POUDEROUX
>>>>
>>>> _PhD, Technical Expert_
>>>>>
>>>>
>>>> 2015-07-15 11:57 GMT+02:00 houssen <houssen at ipgp.fr [9]>:
>>>>
>>>> Seems that it is not possible to filter on vtkDataObject type.
>>>>> But with less generic types (like vtkUnstrucutredGrid for
>>>>> instance), the myFilter works : no error occur, but, viewpoint
>>>>> ends up to be empty. I get "zero" instead of "identity" : why ?!
>>>>>
>>>>> Franck
>>>>>
>>>>> Le 2015-07-14 23:38, houssen a écrit :
>>>>>
>>>>> How to write an identity filter ? (1 input port, 1 output port,
>>>>>> output = input whatever input may be)
>>>>>>
>>>>>> I need to write a custom filter. I am used to VTK "from
>>>>>> outside"
>>>>>> (creating/handling vtk pipelines/scene/object from a main
>>>>>> program)
>>>>>> that is basically without the need to understand all internal
>>>>>> VTK
>>>>>> mechanics (except the SetInputConnection concept). I am not
>>>>>> yet used
>>>>>> to VTK internal mechanics that is necessary for writing a
>>>>>> ParaView
>>>>>> plugin.
>>>>>>
>>>>>> I need my filter to do "complex" stuffs. As I couldn't make it
>>>>>> work,
>>>>>> I simplified as much as possible to obtain finally an identity
>>>>>> filter
>>>>>> (!) : this is still not working. I feel I still miss something
>>>>>> from
>>>>>> VTK internal mechanics.
>>>>>>
>>>>>> As far as I understand, in the constructor, I need :
>>>>>> myFilter::myFilter () { SetNumberOfInputPorts ( 1 );
>>>>>> SetNumberOfOutputPorts ( 1 ); }
>>>>>>
>>>>>> So then I need to implement the FillXXXPortInformation :
>>>>>> int myFilter::FillInputPortInformation ( int vtkNotUsed (
>>>>>> iPort ),
>>>>>> vtkInformation * ipInfo )
>>>>>> {
>>>>>> if ( ipInfo ) ipInfo -> Set (
>>>>>> vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE (), "vtkDataObject" );
>>>>>> //
>>>>>> Filter allowed data types
>>>>>> return 1;
>>>>>> }
>>>>>> int myFilter::FillOutputPortInformation ( int vtkNotUsed (
>>>>>> iPort ),
>>>>>> vtkInformation * ipInfo )
>>>>>> {
>>>>>> if ( ipInfo ) ipInfo -> Set ( vtkDataObject::DATA_TYPE_NAME
>>>>>> (),
>>>>>> "vtkDataObject" ); // Output data type to be created
>>>>>> return 1;
>>>>>> }
>>>>>>
>>>>>> So, now I only need to implement the ProcessRequest gateway:
>>>>>> int myFilter::ProcessRequest ( vtkInformation * ipRequest,
>>>>>> vtkInformationVector ** ipInputVector, vtkInformationVector *
>>>>>> opOutputVector )
>>>>>> {
>>>>>> if ( ipRequest && ipRequest -> Has (
>>>>>> vtkDemandDrivenPipeline::REQUEST_DATA () ) )
>>>>>> if ( ipInputVector && opOutputVector ) opOutputVector =
>>>>>> ipInputVector[0];
>>>>>> return Superclass::ProcessRequest ( ipRequest,
>>>>>> ipInputVector,
>>>>>> opOutputVector );
>>>>>> }
>>>>>>
>>>>>> I believed that I would be the only steps to proceed to get an
>>>>>> identity filter. When I use my identity filter in Paraview, I
>>>>>> get
>>>>>> errors like :
>>>>>> ERROR: In
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>> /.../ParaView-v4.3.1-source/VTK/Common/ExecutionModel/vtkDemandDrivenPipeline.cxx,
>>>
>>>> line 810
>>>>>> vtkPVPostFilterExecutive : Input for connection index 0 on
>>>>>> input port
>>>>>> index 0 for algorithm vtkPVPostFilter(0x16d0ec0) is of type
>>>>>> vtkDataObject, but a vtkPolyData is required.
>>>>>>
>>>>>> Some logic is still missing here : could somebody explain me
>>>>>> what and why ?
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Franck
>>>>>>
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>>>>>
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>>>>
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>>> [14]
>>> http://www.vtk.org/doc/nightly/html/classvtkPassInputTypeAlgorithm.html
>>> [15] mailto:joachim.pouderoux at kitware.com
>>>
>>
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