[vtkusers] Re: problem viewing merged PolyData sets using AppendPolyData

[Goodwin Lawlor]

Hi Denis,

At a guess, I would say your vtkPolyData's have points (geometry) but no
vertices (topology). vtkGlyph3D needs both to work, although in theory it
should only need the points.

Here's a trick to get it to work:

...
...
apd = vtk.vtkAppendPolyData()
apd.AddInput(somePolyData)
apd.AddInput(someMorePolyData)

verts = vtk.vtkMaskPoints()
verts.SetInput(apd.GetOutput())
verts.GenerateVerticesOn()
verts.SetOnRatio(1)

aSphere = vtk.vtkSphereSource()
aSphere.SetRadius(1.0)

spheres = vtk.vtkGlyph3D()
spheres.SetInput(verts.GetOutput())
spheres.SetSource(aSphere.GetOutput())

...
...


hth

Goodwin
"Denis Saussus" <dsaussus at fugro-jason.com> wrote in message
news:F42290EAAE100A4A99A3A9BE2059504FBDB11C at MAIL.fugro-jason.local...
I am plotting a vtkPolyData set containing 3d points so that
they display as spheres.  I can get this to work very easily.

Now I have two vtkPolyData sets, each containing 3d points.
I want to plot them using a single mapper/actor.  I am doing this
simply by using vtkAppendPolyData to merge the two sets into
one.  My problem is that now nothing shows up.

Below is the script I am using.  Help greatly aprpeciated...




##########################
# Why does this not work?
##########################

somePolyData = vtk.vtkPolyData()
# assume this contains some valid 3d points

apd = vtk.vtkAppendPolyData()
apd.AddInput(somePolyData)
apd.AddInput(someMorePolyData)

aSphere = vtk.vtkSphereSource()
aSphere.SetRadius(1.0)

spheres = vtk.vtkGlyph3D()
spheres.SetInput(apd.GetOutput())
spheres.SetSource(aSphere.GetOutput())

mapSpheres = vtk.vtkPolyDataMapper()
mapSpheres.SetInput(spheres.GetOutput())

spheresActor = vtk.vtkActor()
spheresActor.SetMapper(mapSpheres)

ren = vtk.vtkRenderer()
ren.AddActor(spheresActor)
renWin = vtk.vtkRenderWindow()
renWin.AddRenderer(ren)
iren = vtk.vtkRenderWindowInteractor()
iren.SetRenderWindow(renWin)
iren.Initialize()
renWin.Render()
iren.Start()

Denis Saussus

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