[vtkusers] Bug in depth ordering whilst rendering

[Randall Hand]

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?

Can you post  ascreenshot of what's going wrong?

On Nov 28, 2007 8:51 AM, Peter Clifton <pcjc2 at cam.ac.uk> wrote:

>
> On Wed, 2007-11-28 at 09:40 -0500, Jeff Lee wrote:
> > If these artifact are independent of whether you have opacity set or
> > not, it is probably a depth-buffering issue.  What happens when you
> > setenv GL_DEPTH_BITS 32 and relaunch your app?
> > -J
>
> Converting to bash...
>
> GL_DEPTH_BITS=32 ipython -wthread vtk_test.py
>
> (Where vtk_test.py is the very short "Simple Example" at:
> http://scipy.org/Cookbook/MayaVi/mlab
>
> Its still bad from certain camera angles.
>
> AHA... turning on MESA_DEBUG=1..
>
> Mesa warning: glEnable(GL_DEPTH_TEST) but no depth buffer
>
> It does seem like we have a guilty suspect. I'll bug the Intel driver
> guys to see if there _should_ be a depth buffer.
>
> Thanks for the help... I'm sure I didn't see that message last time I
> tried with MESA_DEBUG=1, perhaps the distro version wasn't built with
> all debugging enabled. I've since built it myself from git HEAD.
>
> Is a depth buffer expected on GL Hardware??
>
> Best wishes,
>
> --
> Peter Clifton
>
> Electrical Engineering Division,
> Engineering Department,
> University of Cambridge,
> 9, JJ Thomson Avenue,
> Cambridge
> CB3 0FA
>
> Tel: +44 (0)7729 980173 - (No signal in the lab!)
>
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-- 
----------------------------------------
Randall Hand
Visualization Scientist
ERDC MSRC-ITL
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