[vtkusers] Offscreen rendering bug

[John Norris]

Hi,

I've compiled VTK (from CVS) using Mesa-7.0.3 (including OSMesa) on a
x86_64 linux system.  I've called
vtkGraphicsFactory::SetOffScreenOnlyMode(1)
before creating any of the rendering classes.  I've also called
OffScreenRenderingOn() from my render window before doing anything else
with it.  Still, VTK tries to contact the X server, causing a crash.  It
seems to be happening after line 496 in vtkOpenGLExtensionManager, in
the #ifdef VTK_USE_X block.  The call to
this->RenderWindow->GetGenericDisplayId() leads to a call to
XOpenDisplay(); XOpenDisplay() is explicitly called just a few lines
later, but my program doesn't get that far.

Perhaps the return value of vtkGraphicsFactory::GetOffScreenOnlyMode()
or this->RenderWindow->GetOffScreenRendering() should be checked first.

Thanks,
John
-- 
John Norris
Scientific Visualization Developer
Center for Astrophysical Thermonuclear Flashes