On Fri, Nov 03, 2000 at 10:19:37AM -0800, Ron Bielaski wrote:
> Can someone help refresh my memory about what happens when an
> extension function exists in the library and is called but is
> not supported by the device?
If you mean specifically WRT the Linux ABI, the correct answer at
this point is "whatever Brian's implementation in XFree86 4 does". There
was some contentious discussion on this ca. Nov. 5 1999 on the mailing
list, in the context of "if I get a pointer back from
glXGetProcAddressARB and call it with a context current that doesn't
support that extension, what should happen?"
In the abstract spec sense, behavior when calling an unsupported
extension is undefined by the GL and GLX Specifications.
> Is this a noop or error?
It's an application error; making such an invalid call doesn't even
necessarily fall under the "will not terminate the GL" caveat in the
Specification IMO. More benign failure modes, such as returning
GL_UNSUPPORTED_OPERATION or generating a GLX error, are probably
desirable when possible - but they aren't always possible.
> I didn't notice a description in the spec or an issue and wasn't
> able to determine the outcome in the mail archive.
I don't believe we had resolution, or if we did, it wasn't
documented. This needs to be pinned down in the ABI and the
glXGetProcAddressARB specifications.
Jon Leech
SGI
