[Paraview] Programmable sphere source - update position each timestep from csv file

[James Avery]

Hi Cory,

Thanks for your help. Sorry if the message was rambling, but I had a 
script which made the spheres is called from the python shell as you 
suggest. However, I was looking for a solution that was automatically 
updated when changing the timestep in the GUI - I was not clear on this, 
apologies. So I thought I had to use a programmable source or 
programmable filter.

The spheres are designed to indicate locations inside a larger dataset, 
so I compromised by having a spherical clip which updates its centre. 
The code for the programmable filter to do this is:

import vtk
import csv
csvfilename = '../../resources/vtk/testpos.csv'
input = self.GetInputDataObject(0, 0)
output = self.GetOutputDataObject(0)

t = 
self.GetInputDataObject(0,0).GetInformation().Get(vtk.vtkDataObject.DATA_TIME_STEP())
TimePoint  = int(t)
     # read the specific line from the csv file
Centre = [0.0, 0.0, 0.0]
count = 0

with open(csvfilename) as f:
     r = csv.reader(f)
     for row in r:
         if count == TimePoint:
             Centre = [float(i) for i in row]
             break
         count += 1

s = vtk.vtkSphere()
s.SetCenter(Centre)
s.SetRadius(10)

clip = vtk.vtkClipDataSet()
clip.SetInputDataObject(input)
clip.SetClipFunction(s)
clip.SetValue(0.0)
clip.InsideOutOn()
clip.Update()
print clip

output.ShallowCopy(clip.GetOutputDataObject(0))

Probably not the most elegant solution, but it seems to be doing the job!

Kind regards,

James

On 14/07/2016 21:38, Cory Quammen wrote:
> Hi James,
>
> Instead of the Programmable Source, you should be able to use the
> paraview.simple module to do this in a Python script. Here's code to
> create and show a Sphere source:
>
> s = Sphere()
> Show(s)
>
> You can update the sphere position with
>
> s.Center = [1, 2, 3]
>
> Obviously, you can use the above line in your loop over the positions
> from the CSV file. After each Center update, you should re-render with
>
> RenderAllViews()
>
> You can run Python script files through the Python console by clicking
> the "Run Script" button and navigating to your script file.
>
> HTH,
> Cory
>
> On Wed, Jul 13, 2016 at 4:59 AM, James Avery <j.avery at ucl.ac.uk> wrote:
>> Hi all,
>>
>> I am trying to create a programmable source to create a sphere, the location
>> of which updates per time step based on coordinates in a csv file. However,
>> I have sort of got my head around the python library (thanks to tracing what
>> I do in the GUI!), but I think one needs to use the vtk library instead? I
>> have written a python script which does the job when called from the python
>> shell, but this is not updating when the timestep changes. I have tried
>> adapting this code to work as a programmable source, but to no avail.
>>
>> Here is the code for the programmable source I have so far:
>>
>> import vtk
>> import os
>> import csv
>>
>> csvfilename = '../../resources/vtk/testpos.csv'
>> csvfilename= os.path.abspath(csvfilename)
>>
>> animationScene1 = GetAnimationScene()
>> target = int(animationScene1.AnimationTime)
>> print "Target value is: " + str(target)
>>
>> pos = [0.0, 0.0, 0.0]
>> count=0
>> with open(csvfilename) as f:
>>      r = csv.reader(f)
>>      for row in r:
>>          print "Current row :" + str(row)
>>          if count == target:
>>              print "found it"
>>              pos = [float(i) for i in row]
>>              break
>>          count += 1
>> print "Pos is now : " + str(pos)
>>
>> s=vtk.vtkSphereSource()
>> s.SetCenter(pos)
>> s.SetRadius(10)
>> s.Update()
>>
>>
>> The csv stuff works as far as I can tell, but it gives an error because
>> GetAnimationScene is not defined. However, there is another problem, even if
>> I ignore all of the time dependent things and just try to create a sphere in
>> this manner:
>>
>> import vtk
>> s=vtk.vtkSphereSource()
>> s.SetCenter([0,0,0])
>> s.SetRadius(10)
>> s.Update()
>>
>> there are no errors, but no sphere either! So I guess I am missing something
>> fundamental about the difference between python scripting and programmable
>> sources. Further, I wonder if it would be easier to change the position of
>> an already created sphere source with a programmable filter instead?
>>
>> Has anybody solved a similar problem and can point me in the correct
>> direction? Any help would be greatly appreciated.
>>
>> Kind regards,
>>
>> James
>>
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