[vtk-developers] vtkgl::LoadExtension not exported

[Kathleen S. Biagas]

We want to be able to provide OSMesa support even if vtk was not built
with Mesa.

To accomplish this, we are currently trying:
1) overriding vtkXOpenGLRenderWindow with our own OSMesaRenderWindow
class
2) overriding vtkOpenGLExtensionManager class with an 'osmesa' one,
which allows us to use OSMesaGetProcAddress without
VTK_OPENGL_HAS_OSMESA being defined.

We need  vtkgl::LoadExtension to be exported, so that VTK will use the
mesa extensions when using our window.


Kathleen



On Wed, 2013-04-17 at 14:24 -0700, Burlen Loring wrote:
> Hi Kathleen,
> 
> Have you tried to use the vtkOpenGLExtensionManager? It has these 
> functions. If you initialized it with an vtkOSOpenGLRenderWindow it 
> should be able to load the extensions. You probably have a good reason 
> not to, but I'm curious to know why that doesn't work.
> 
> Burlen
> 
> On 4/17/2013 2:01 PM, Kathleen S. Biagas wrote:
> > In our attempts to support OSMesa at runtime, we've run into a snag in
> > that vtkgl::LoadExtension and vtkgl::GLVersionExtensionsString are not
> > exported, and thus not accessible in our implementation.
> >
> > Are there any objections or unforseen-on-my-part consequences to
> > modifying ParseOGLExt.cxx to export those symbols?
> >
> > Something along the lines of:
> >
> > Left file: /VTK-Unmodified/Utilities/ParseOGLExt/ParseOGLExt.cxx
> > Right file: /VTK-Modified/Utilities/ParseOGLExt/ParseOGLExt.cxx
> > 693c693
> > <   hfile << endl << "  int LoadExtension(const char *name, "
> > ---
> >>    hfile << endl << "  extern int VTKRENDERINGOPENGL_EXPORT
> > LoadExtension(const char *name, "
> > 696c696
> > <   hfile << endl << "  const char *GLVersionExtensionsString();" <<
> > endl;
> > ---
> >>    hfile << endl << "  extern VTKRENDERINGOPENGL_EXPORT const char
> > *GLVersionExtensionsString();" << endl;
> >
> >
> > Kathleen
> >
> >
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