<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Wed, Apr 2, 2014 at 6:55 AM, Richard Whitehead <span dir="ltr"><<a href="mailto:richard.whitehead@vivosight.com" target="_blank">richard.whitehead@vivosight.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Since moving to VTK 6.1 I'm having a problem where VTK pops up an error box saying</div><div><div>
ERROR: In E:\VTK\VTK-6.1.0\Rendering\OpenGL\vtkOpenGLExtensionManager.cxx, line 757</div><div> vtkOpenGLExtensionManager (0000000003A83120): Extension GL_VERSION_1_2 could not be loaded.</div>
</div><div><br></div><div>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.</div><div><br></div><div>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.</div>
<div><br></div><div>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.</div><div><br></div><div>I have checked the relevant code in VTK GIT but there have been no recent fixes.</div>
<div><br></div><div>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.</div></div></blockquote><div><br></div><div>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 </div>
<div>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. </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr"><div>Options would seem to include:</div><div> Changing vtkOpenGLVolumeTextureMapper3D::Initialize to load a newer version</div>
<div> Removing the explicit load of the deprecated version in vtkOpenGLExtensionManager::SafeLoadExtension</div><div> Not failing if the main version loads but the deprecated version fails to load</div><div> Changing the build system to not include the deprecated version</div>
<div> Loading just the latest version at runtime</div><div>But I don't know anything about OpenGL or the details of how it is used in VTK so I can't decide.</div><div><br></div><div>Please can someone advise what should be changed.</div>
<div><br></div><div><br></div><div>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.</div>
<div><br></div><div>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 ....."</div>
<div>It did this because of the contents of a text string it was given to parse... and here I gave up.</div></div></blockquote><div><br></div><div>I see. Let me send you a patch for you to try. </div><div><br></div><div>
- Aashish</div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><br></div><br clear="all"><div>Many thanks,</div><div><br></div><div>
Richard</div><div><br></div><div><br></div>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br>| Aashish Chaudhary <br>| R&D Engineer <br>| Kitware Inc. <br>| <a href="http://www.kitware.com">www.kitware.com</a>
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