[vtkusers] Transparent NaN color with OpenGL2

[Ken Martin]

This should be fixed in master now. I added methods to force an actor to
treat itself as Opaque or Translucent regardless of other factors. So in
your example even though you have some less than 1.0 alpha values in your
LUT you could call yourActor->ForceOpaqueOn() to force it to be treated as
Opaque.

Thanks
Ken

Ken Martin PhD
Chairman & CFO
Kitware Inc.
28 Corporate Drive
Clifton Park NY 12065
ken.martin at kitware.com
919 869-8871 (w)


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-----Original Message-----
From: vtkusers [mailto:vtkusers-bounces at vtk.org] On Behalf Of Karsten
Tausche
Sent: Thursday, September 17, 2015 4:15 AM
To: vtkusers at vtk.org
Subject: [vtkusers] Transparent NaN color with OpenGL2

Hi,

I'm using vtkLookupTable::SetNanColor to hide cells with NaN scalar values
in my data sets (alpha value set to zero). This worked fine with the old
OpenGL backend, but seems to break the depth test with OpenGL2.

See the attached images: the red/blue quad is always rendered in the
foreground, no matter how you rotate the camera. This happens when you set
the alpha value for NaN-values to something different to 1 for both planes.

I tested this with today's nightly branch, but it seems to be broken in the
OpenGL2 backend since a while. (On Nvidia, Windows 8.1x64, MSVC2015)

Is this a bug in the new backend, or is there some parameter that I have to
configure for this setup?

Thanks,
Karsten