Re: [PyOpenGL-Users] "Attempt to retrieve context when no valid context" when calling glVertexAttribPointer in GL ES 2

[JP L. <jpl...@gm...>]

I've now tried a few other things, like setting
OpenGL.CONTEXT_CHECKING=True and forcing an ES 2.0 context specifically,
and experimenting with SDL_GL_CONTEXT_FLAGS, but nothing seems to work.
Debug contexts don't seem supported, they're only core as of 4.3.

Searching this mailing list for "raspberry" returns only this thread so it
seems reasonable to assume that PyOpenGL has never worked on the Pi without
significant modifications; guess I should have searched this list before I
started.

On Wed, Jan 3, 2018 at 12:00 AM, Ian Mallett <ia...@ge...> wrote:

> On Tue, Jan 2, 2018 at 10:44 PM, JP LeBreton <jpl...@gm...> wrote:
>
>> PySDL2 and PyOpenGL have been working fine together for this application
>> on x86[_64] Linux, macOS, and Windows, on Intel and Nvidia GPUs, but I
>> realize the Pi is a fairly different environment and drivers play a large
>> role.
>>
> It is distressingly common (less so, today, but still) to get an
> application that works perfectly on a variety of (arch/PCI, GPU, OS,
> driver) tuples, but is actually incorrect. It is also possible to have
> bugs, usually in the driver (I have, for example, several outstanding ones
> reported on various Linux graphics drivers) making perfect programs break.
>
>
>> I'll read up on debugging with glGetError...
>>
> ​Shortly after I sent my email, I remembered that PyOpenGL does some
> amount of its own checking, which IIRC includes implicit `glGetError(...)`.
> Perhaps creating a debug context
> <https://www.khronos.org/opengl/wiki/Debug_Output> would enable more
> checks, assuming the Pi supports it (which IDR offhand). I might also
> suggest some kind of graphics debugger, like RenderDoc.
>
> Although . . . the error does seem to indicate at least the basic nature
> of the problem rather clearly. Perhaps the context exists, but is invalid
> for some reason (Unsupported flags? Invalid version? Invalid size?).
>
> Ian
>