[Paraview] Adding/writing paraview filters

Thu Oct 22 09:23:22 EDT 2009

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-berk

On Wed, Oct 21, 2009 at 3:41 PM, pat marion <pat.marion at kitware.com> wrote:
> Hi David,
>
> The paraview devel list is paraview-developers at paraview.org.  It used
> to be private but now it is public.  I was subscribed internally by
> Kitware, I'm not sure where the public sign up is located.
>
>
>>   <SourceProxy name="TransformFilter" class="vtkTransformFilter"
>>    label="Transform">
>>
>> 1) What is a source proxy? This filter will use the vtkTransformFilter
>> filter, and it will be called "Transform" in the paraview menu.
>
> There is a method vtkSMProxy* vtkSMProxyManager::NewProxy (const char
> * groupName, const char* proxyName).  Calling this with group=sources
> and name=TransformFilter will create a new vtkSMSourceProxy.  So
> basically "vtkSM" is prepended to the xml element name to create a
> class name.  vtkSMSourceProxy is the base class for all sources such
> as readers and filters.  For most cases vtkSMSourceProxy is
> sufficient, you can control the vtk filter completely through
> Properties defined on the source proxy.  But if you look in
> rendering.xml you'll see a lot of xml elements that are just plain old
> <Proxy/> (corresponding to vtkSMProxy) or more fancy ones like
> <RenderViewProxy/> (corresponding to vtkSMRenderViewProxy).  In cases
> of things like vtkSMRenderViewProxy, the class is created to handle
> extra logic that is not handled simply through Properties.
>
> When you create the transform filter in the paraview gui, only the
> vtkSMSourceProxy is created on your machine, the vtkTransformFilter
> might be living on a server somewhere else (unless you are in builtin
> mode of course).  Setting a property on the source proxy causes a
> method to be called on the vtkTransformFilter on the server.
>
> Sorry I can't answer all your questions right now, but it's a start.
>
> Pat
>
> On Wed, Oct 21, 2009 at 3:13 PM, David Doria <daviddoria at gmail.com> wrote:
>> First, just curious - why is there not a separate -devel list for
>> Paraview as there is for vtk/itk?
>>
>> I have some time this week and I was hoping to try to implement these:
>> http://public.kitware.com/Bug/view.php?id=8999
>> http://public.kitware.com/Bug/view.php?id=8998
>>
>> For the ICP interface, all that needs to be selected is two items in
>> the pipeline and have a few text boxes to specify some parameters.
>> For the Landmark Transform interface, two sets of N points need to be
>> selected, one from each of the two selected items in the pipeline.
>>
>> This seems like it should be relatively easy to do, but the
>> plugin/servermanager/module/proxy terminology is quite confusing to
>> me.
>>
>> Is this the guide I should be following?
>> http://www.itk.org/Wiki/Extending_ParaView_at_Compile_Time
>>
>> That example shows how to add a source, but I imagine it is very
>> similar to add a filter? I looked at the paraview user guide and the
>> rest of the links on the wiki, but I didn't see anything like the
>> following analysis/descriptions - did I miss something major here?
>>
>> I looked at the TransformFilter in filters.xml as a starting point -
>> here are some line by line comments/questions about it:
>>
>>   <SourceProxy name="TransformFilter" class="vtkTransformFilter"
>>    label="Transform">
>>
>> 1) What is a source proxy? This filter will use the vtkTransformFilter
>> filter, and it will be called "Transform" in the paraview menu.
>>
>>    <Documentation
>>       long_help="This filter applies transformation to the polygons."
>>       short_help="Transform polygonal data.">
>>      The Transform filter allows you to specify the position, size,
>> and orientation of polygonal, unstructured grid, and curvilinear data
>> sets.
>>    </Documentation>
>>
>> 2) Where does this help text get displayed?
>>
>>    <InputProperty
>>       name="Input"
>>       command="SetInputConnection">
>>
>> 3) We want to call SetInputConnection() on the input, which is called
>> Input. Is Input taken to be the selected item in the pipeline you are
>> attempting to apply the filter to?
>>
>>          <ProxyGroupDomain name="groups">
>>            <Group name="sources"/>
>>            <Group name="filters"/>
>>          </ProxyGroupDomain>
>>
>> 4) I'm assuming "Group name" means to add this to the "Filters" menu
>> in paraview? Why is "sources" also a "group name"?
>>
>>          <DataTypeDomain name="input_type">
>>            <DataType value="vtkPointSet"/>
>>          </DataTypeDomain>
>>
>> 5) What is "DataTypeDomain"? I understand that vtkPointSet is the
>> input type to vtkTransformFilter.
>>
>>          <Documentation>
>>            This property specifies the input to the Transform filter.
>>          </Documentation>
>>     </InputProperty>
>>
>> 6) Where does this documentation get displayed/placed?
>>
>>     <ProxyProperty name="Transform" command="SetTransform">
>>
>> 7) What is a ProxyProperty vs an InputProperty?
>>
>>           <ProxyGroupDomain name="groups">
>>              <Group name="transforms"/>
>>           </ProxyGroupDomain>
>>
>> 8) Where does this "group" called "transforms" appear?
>>
>>           <ProxyListDomain name="proxy_list">
>>              <Proxy group="extended_sources" name="Transform3" />
>>           </ProxyListDomain>
>>
>> 9) What is "extended_sources" and "Transform3"?
>>
>>           <Documentation>
>>             The values in this property allow you to specify the
>> transform (translation, rotation, and scaling) to apply to the input
>> dataset.
>>           </Documentation>
>>
>> 10) I see that this string gets displayed if you hover over any of the
>> items in the transform GUI.
>>
>>
>> Even though they are similar, the two things I am trying to implement
>> could be quite different because with the Transform filter, you simply
>> choose an object in the pipeline and apply that filter to the object -
>> with my things you have to select TWO things in the pipeline (the
>> source and destination objects, in the case of ICP). Is there an easy
>> way to do this? Can you simply ctrl+click items in the pipeline to
>> select them and then sort out the inputs in the filter?
>>
>> Where is the code that creates the GUI (to take user input of the
>> transformation) for this filter?
>>
>> Can someone please help get me started? I think this will be a useful
>> exercise - I intend to document the process of adding a filter and
>> constructing the interface GUI and add it to the wiki so that future
>> users can hopefully contribute to the project with less of a learning
>> curve.
>>
>> Thanks!
>>
>> David
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