[vtkusers] Re: Bug in depth ordering whilst rendering

[Mönch, Tobias]

Hi Peter,

for me it looks like a problem I had 2 years ago but discontinued fixing it. 

Here is the link to my example of the problem:

http://public.kitware.com/pipermail/vtkusers/attachments/20050922/06f2d81a/surface_inside_out-0001.bin


...and here the original thread:

http://public.kitware.com/pipermail/vtkusers/2005-September/081864.html


Finally, I tried vtkDepthSortPolyData as proposed by someone. It seemed to fix the problem, but slowed the surface rendering extremely so that it became unusable.

I tested it 2 years ago with vtk4.x nightly via C++ and currently vtk5.x nightly with Java from within Matlab but still get the same problem (also on different machines).

Best wishes,
Tobias



>
> hrm.. That is weird... looks almost like your Depth Buffer is working
> entirely backward, like glDepthFunc(GL_GREATER).  I'm not familiar with
> MayaVI or scipy so I can't offer much in the way of help.
>
> Have you tried recompiling ipython?
>
> On Nov 29, 2007 12:52 PM, Peter Clifton <pcjc2 at cam.ac.uk> wrote:
>
> > On Thu, 2007-11-29 at 09:21 -0600, Randall Hand wrote:
> > > Whether or not the Depth Buffer exists is typically a function of the
> > > arguments used to create the GL context.  You can create contexts
> > > without a Depth Buffer, but it's unusual.
> > >
> > > other things to look into:
> > > * Near-Far clipping Plane values .. have you tried calling
> > > renderer->ResetCameraClippingRange() ?  if your near plane is too
> > > close to 0, you'll lose alot of resolution, causing artifacts.
> > > * Are you creating your own GL contexts? Or using the built-in VTK
> > > stuff?
> >
> > VTK stuff... I'm attaching the info here. I'm really new to VTK, so am
> > not entirely familiar with its correct usage.
> >
> > When I run a simple test program:
> >
> > ipython -wthread vtk_test.py
> >
> > Where vtk_test.py is from the first example here:
> > http://scipy.org/Cookbook/MayaVi/mlab
> >
> > I get the attached screenshot from some camera angles. A correct example
> > is at the above website.
> >
> > Thanks for helping!
> >
> > Best wishes,
> >
> > Peter C.
> >
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