[vtk-developers] OSMesa depth buffer issues

[Jeff Lee]

I am surprised it doesn't honor

 MESA_GLX_DEPTH_BITS=24
 export MESA_GLX_DEPTH_BITS

- this seems to work fine for me.
-Jeff

On Thu, Jan 28, 2010 at 4:30 PM, Francois Bertel <
francois.bertel at kitware.com> wrote:

> Hi Burlen,
>
> I just looked at vtkWindow/vtkRenderWindow and too bad, there is no
> API to let the user specify the render window settings regarding the
> depth in bit of each type of buffer (color buffer, depth buffer,
> stencil buffer, accumulation buffers) in the framebuffer.
> That would have be better than hardcoding the values in
> vtkXOpenGLRenderWindow.
>
> Anyway the typical values for on-screen are 24 bits for depth buffer,
> 8 bits for stencil buffer, 16 bits per channel for accumulation
> buffer.
> What happen in your case if you use these values instead the one you
> provided in your patch?
>
> On Thu, Jan 28, 2010 at 4:14 PM, burlen <burlen.loring at gmail.com<https://mail.google.com/a/cdnorthamerica.com/?view=cm&tf=0&to=burlen.loring@gmail.com>>
> wrote:
> > Hi Guys,
> >
> > I'm having some issues in ParaView that relate back to VTK's OSMesa
> > rendering context. Specifically VTK asks OSMesa for the default RGBA
> > context, which only has a 16 bit depth buffer. That's causing some
> artifacts
> > and compositing issues in certain situations. for example:
> >
> >
> >
> http://nashi-submaster.ucsd.edu/movies/PV/tube-filter-artifact/mesa-artifacts.png
> >
> >
> http://nashi-submaster.ucsd.edu/movies/PV/tube-filter-artifact/mesa-artifacts-decomp.png
> >
> > Explicitly requesting a 32 bit depth buffer solves the problems.
> >
> > I attached a small patch that makes this change in VTK. It replaces the
> call
> > to OSMesaCreateContext with one to OSMesaCreateContextExt specifying a 32
> > bit depth buffer and carries forward the current default values for
> > accumulation and stencil buffers. I guess this function was The
> > OSMesaCreateContextExt was added to in mesa release 3.5, the current
> release
> > is 7.7.
> >
> > Is this the right fix? Or is something more sophisticated necessary? e.g.
> > run time configurable. And while we're on the subject, are OSMesa's other
> > buffer defaults reasonable? accum (8 bits per channel) and stencil
> buffers
> > (16 bits).
> >
> > Thanks
> > Burlen
> >
> >
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>
>
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