From Colin McDonald, "Add test for GL_EXT_framebuffer_object extension : osg uses osg::FBOExtensions to check if Frame Buffer Objects are

available.  But this just checks if the fbo functions can be called.
It doesn't check if the OpenGL renderer supports fbos.  For indirect
rendering on linux the client side capability may be different from
the display server, which can lead to mipmapped textures failing to
render.  I've added a fbo extension check.
"

src/osg/FrameBufferObject.cpp

@@ -105,7 +105,8 @@ FBOExtensions::FBOExtensions(unsigned int contextID)
 #if !defined(OSG_GLES1_AVAILABLE) && !defined(OSG_GLES2_AVAILABLE)
     _supported = _supported &&
         glFramebufferTexture1D != 0 &&
-        glFramebufferTexture3D != 0;
+        glFramebufferTexture3D != 0 &&
+        isGLExtensionOrVersionSupported(contextID, "GL_EXT_framebuffer_object",3.0f);
 #endif
 
     LOAD_FBO_EXT(glBlitFramebuffer);