Great! I just experimented with your plugin, I have to say that's pretty
cool!
On 05/31/2014 04:47 PM, Andrew Maclean wrote:
Burlen,
Thankyou so much for your quick response. The script works fine. I
am a bit of a ParaView novice when it comes to scripting so thanks for
the help!
This problem arose because I was looking at the VTK Parametric
Functions and wondering why they looked so terrible in ParaView and
yet there were no issues displaying them in VTK.
So I wrote an XML plugin and discovered that I couldn't access the
scalars or normals. In the case of normals, for non-orientable
surfaces the normals become really important and they are generated
with the surface, so you need access the data. Paraview can do this if
it knows the name of the dataset.
It turns out that when I wrote vtkParametricFunctionSource (way back
in 2003 I think!) I never named the normal or scalar arrays. So I will
fix this, modernise the code and update the documentation in this
coming week.
If you are interested, here is a first attempt at the xml plugin. With
your script we get some beautiful results in Paraview. Of course I
need to add in the parameters for all the other surfaces. I have only
done ParametricConicSpiral and ParametricMobius.
First: Use Manage Plugins to import the xml script.
Then:
1) Find ParametricSource in Sources and select a function e.g Mobius,
(Minimum V = -0.2, Maximum V = 0.2) specify a scalar mode and you will
get a very ordinary mobius strip.
2) Apply your script as a programmable filter and select the coloring
to be scalars and you get a beautifully shaded surface.
3) Then apply the Glyph filter using the Normals as vectors and you
get a nice display of the vectors on the surface. Use a scale of
(-1,-1,-1) if you want to invert the normals.
You get some beautiful images.
Regards
Andrew
On Sun, Jun 1, 2014 at 3:03 AM, Burlen Loring <[email protected]
<mailto:[email protected]>> wrote:
Hi Andrew,
I see a couple of things in your script. First is normals and
scalars are data set attributes. so you need to access them
through one of those classes, ex vtkPointData.
Correct me if I'm wrong but, although in VTK 6 you generally don't
need to shallow copy the input to filters I think it's still
probably a bad practice to modify the arrays in the input dataset.
I think what you want to do is copy the geometric structure of the
input and then make a deep copy of normals and scalars arrays, and
rename the copys. Copy structure rather than shallow copy since
with a shallow copy you'd still end up modifying the arrays in the
input dataset.
Finally scalars and normals may not be present. I know you'd
probably handle that in your final script, ;-)
given all that, here's what I came up with:
def copyAndNameArray(da, name):
if da is not None:
outda = da.NewInstance()
outda.DeepCopy(da)
outda.SetName(name)
return outda
else:
return None
pdi = self.GetPolyDataInput()
pdo = self.GetPolyDataOutput()
pdo.CopyStructure(pdi)
pdo.GetPointData().SetNormals( \
copyAndNameArray(pdi.GetPointData().GetNormals(), 'Normals'))
pdo.GetPointData().SetScalars( \
copyAndNameArray(pdi.GetPointData().GetScalars(), 'Scalars'))
print 'Normals=%s'%(str(pdo.GetPointData().GetNormals()))
print 'Scalars=%s'%(str(pdo.GetPointData().GetScalars()))
Curious to hear from other developers as to if I'm on target about
not modifying arrays in the input or if this is overkill given the
new VTK 6 pipeline.
Burlen
On 05/30/2014 07:29 PM, Andrew Maclean wrote:
I have a source object that produces a polydata object.
Unfortunately the normals and scalars are unnamed. How do I
access these and name them in ParaView.
I thought something like this may work in a Programmable Filter:
pdi = self.GetPolyDataInput()
pdo = self.GetPolyDataOutput()
pdi.GetNormals().SetName('Normals')
pdi.GetScalars().SetName('Scalars')
pdo = pdi
However, I can't see the array names.
This sort of thing works Ok in a Python Script:
# Name the arrays
randomHillsSource.GetOutput().GetPointData().GetNormals().SetName('Normals')
randomHillsSource.GetOutput().GetPointData().GetScalars().SetName('Scalars')
# pd = randomHillsSource.GetOutput().GetPointData()
# print pd
Is it possible to do this on ParaView?
Thanks in advance for any help.
Andrew
--
___________________________________________
Andrew J. P. Maclean
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Andrew J. P. Maclean
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