[vtkusers] VTK error dialog due to OpenGL problem

[Aashish Chaudhary]

On Wed, Apr 2, 2014 at 6:55 AM, Richard Whitehead <
richard.whitehead at vivosight.com> wrote:

> Since moving to VTK 6.1 I'm having a problem where VTK pops up an error
> box saying
>   ERROR: In
> E:\VTK\VTK-6.1.0\Rendering\OpenGL\vtkOpenGLExtensionManager.cxx, line 757
>   vtkOpenGLExtensionManager (0000000003A83120): Extension GL_VERSION_1_2
> could not be loaded.
>
> I think this problem was happening in 6.0 but only as a warning, and since
> my app worked I didn't worry about it: now I can't ignore it.
>
> VTK 6.1 source and a simple test app were both built on the same machine,
> using CMake and then Visual Studio 2012 in both cases.  I'm trying to run
> the app on the same machine it was built on.  It is a new Dell running
> Windows 7 64 bit, the graphics is an integrated Intel HD Graphics 4600.
>
> I have updated my graphics drivers to the latest Intel drivers to no
> effect and I think I must conclude that this deprecated interface is no
> longer supported.
>
> I have checked the relevant code in VTK GIT but there have been no recent
> fixes.
>
> I've investigated why VTK is trying to load these deprecated functions,
> which I explain below, but I don't know what to do about it.
>

I believe it was querying for 1_2 to make sure that features needed for
rendering are supported. As the 1_2 is quite old and
newer drivers don't event list it any more and that's why you are getting
these errors. I will have a look at the code.


> Options would seem to include:
>   Changing vtkOpenGLVolumeTextureMapper3D::Initialize to load a newer
> version
>   Removing the explicit load of the deprecated version in
> vtkOpenGLExtensionManager::SafeLoadExtension
>   Not failing if the main version loads but the deprecated version fails
> to load
>   Changing the build system to not include the deprecated version
>   Loading just the latest version at runtime
> But I don't know anything about OpenGL or the details of how it is used in
> VTK so I can't decide.
>
> Please can someone advise what should be changed.
>
>
> vtkOpenGLVolumeTextureMapper3D::Initialize explicitly loads
> GL_VERSION_1_2, and when you load that,
> vtkOpenGLExtensionManager::SafeLoadExtension explicitly also loads the
> DEPRECATED version, and this fails because none of the entry points are
> found.
>
> The reason it thinks 1.2 is supported is that during the
> build, ParseOGLExt.cxx writes a file called vtkgl.cxx that includes a
> string vtkgl::GLVersionExtensionsString which in my case
> includes "GL_VERSION_1_2 GL_VERSION_1_2_DEPRECATED ....."
> It did this because of the contents of a text string it was given to
> parse... and here I gave up.
>

I see. Let me send you a patch for you to try.

- Aashish


>
> Many thanks,
>
> Richard
>
>
>
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-- 
| Aashish Chaudhary
| R&D Engineer
| Kitware Inc.
| www.kitware.com
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