[Paraview] Disabling polygon offset (z-fighting prevention) in Paraview

[Paul Edwards]

I get the following error when calling "from libvtkRendering.so import
vtkMapper":

     ImportError: dynamic modules does not define init function

Can anyone see what I am doing wrong?

I'm on linux with an up-to-date development version.

Thanks in advance,
Paul

PS I'm having problems with contour lines showing through the surface.
 Commenting out the lines (199 & 200) in vtkProcessModule.cxx but this is
for a user who has an existing version...

On 30 October 2009 12:04, Utkarsh Ayachit <utkarsh.ayachit at kitware.com>wrote:

> Oluminde,
>
> It makes sense to provide an option in the "Settings" dialog to
> tweak/disable offsetting for resolving z-fighting. I've added a
> feature request to the bug tracker:
> http://paraview.org/Bug/view.php?id=9801
>
> To fix this without recompiling, here's a crazy hack to overcome this
> issue in builtin mode (i.e. when not connected to server):
> Before loading any datasets
> * open python shell
> * Run the following commands:
>  > import os
>  > if os.name == "posix":
>  >      from libvtkRendering.so import vtkMapper
>  > else:
>  >      from vtkRenderingPython import vtkMapper
>  > vtkMapper.SetResolveCoincidentTopologyToOff()
>
> If connected to a server, you can run the same python commands as part
> of the python script for a programmable source or filter.
>
> Utkarsh
>
>
> On Fri, Oct 30, 2009 at 6:48 AM, Utkarsh Ayachit
> <utkarsh.ayachit at kitware.com> wrote:
> > Ken,
> >
> > Offsetting the points/lines handles the cases when people try to
> > render two overlapping datasets: one as surface and other as
> > wireframe, and they don't necessarily want to show surface with edges
> > (say they want scalar coloring for both surface and the wireframe). I
> > believe Jean Favre has several such use cases.
> >
> > Utkarsh
> >
> > On Mon, Oct 26, 2009 at 1:18 PM, Moreland, Kenneth <kmorel at sandia.gov>
> wrote:
> >> Utkarsh,
> >>
> >> After reading this question from Olumide, I noticed that ParaView now
> turns
> >> on ZShift for lines and points (vtkProcessModule.cxx, 198-199).  I don’t
> >> know why this is.  This effect is turned off when drawing surface+edges
> >> (vtkOpenGLCoincidentTopologyResolutionPainter.cxx, 56-58) because it
> >> automatically switches to offsetting the polygons the polygons back
> >> (vtkOpenGLRepresentationPainter.cxx, 79-85).  Should we remove those two
> >> lines from vtkProcessModule.cxx?
> >>
> >> -Ken
> >>
> >>
> >> On 10/26/09 12:53 AM, "Olumide" <50295 at web.de> wrote:
> >>
> >> Hi -
> >>
> >> I use Paraview not for visualizing datasets, but for inspecting
> >> polygonal meshes and the operations I perform on them. My work involves
> >> computing various points and line segments on meshes, and I use
> >> VTK/Paraview to see if the points and line segments are where they ought
> >> to be (if not, I conclude that there's a bug in my code and then proceed
> >> to hunt it down).
> >>
> >> <Digression>
> >> Why I use VTK for this task: VTK is the the only publicly available 3d
> >> graphics file format I'm aware of that explicitly supports and points,
> >> lines, and meshes, and has a viewer for viewing these entities. Most
> >> other 3d graphics file formats either support surfaces alone or have no
> >> ready-made viewers.
> >> </Digression>
> >>
> >> Lately however, upon closer inspection, I've noticed that many of the
> >> points and line segments that I compute appear to hover above the mesh
> >> they are computed from and never quite touch it, and points never seem
> >> to lie on the line segments they are supposed to. For example, see:
> >> http://i17.photobucket.com/albums/b52/videohead/SurfaceError.png
> >> (note that the yellow line segment hover above the blue surface in the
> >> horizon)
> >>
> >> After much experimentation, debugging and consultation, I now suspect
> >> that this is caused by polygon offset in Paraview, designed to prevent
> >> z-fighting. I would therefore like to know:
> >>
> >> (i.) if my suspicion is correct i.e. Paraview implement polygon offset
> >> for preventing z-fighting in this case
> >>
> >> (ii.) if the above is true, how polygon offset can be disabled without
> >> recompiling the source
> >>
> >> Thanks,
> >>
> >> - Olumide
> >>
> >> _______________________________________________
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> >>
> >>
> >>
> >>    ****      Kenneth Moreland
> >>     ***      Sandia National Laboratories
> >> ***********
> >> *** *** ***  email: kmorel at sandia.gov
> >> **  ***  **  phone: (505) 844-8919
> >>     ***      web:   http://www.cs.unm.edu/~kmorel
> >>
> >>
> >
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