Re: [PyOpenGL-Users] No valid context

[Ian M. <ia...@ge...>]

On Sun, Apr 19, 2020 at 8:20 AM physkets via PyOpenGL-Users <
pyo...@li...> wrote:

> Hi!
>
> I'm trying to use pyGLFW to make a simple coloured quad, but I fail with
> the following error message:
>
> Traceback (most recent call last):  File "first.py", line 121, in
> <module>    gl.glVertexAttribPointer(LOCATION, 2, gl.GL_FLOAT, False,
> STRIDE, OFFSET)  File
> "/usr/lib/python3.8/site-packages/OpenGL/latebind.py", line 63, in
> __call__    return self.wrapperFunction( self.baseFunction, *args, **named
> )  File "/usr/lib/python3.8/site-packages/OpenGL/GL/VERSION/GL_2_0.py",
> line 469, in glVertexAttribPointer    contextdata.setValue( key, array )
> File "/usr/lib/python3.8/site-packages/OpenGL/contextdata.py", line 58, in
> setValue    context = getContext( context )  File
> "/usr/lib/python3.8/site-packages/OpenGL/contextdata.py", line 40, in
> getContext    raise error.Error(OpenGL.error.Error: Attempt to retrieve
> context when no valid context
> I am attaching the program that gives me that error along with the shaders.
>
> Am I doing something wrong?
>

FWIW I can't reproduce the issue here, although I note that line 121
mentioned in the traceback does not correspond to that line in the attached
code, so I don't know if the difference matters. Anyway, the code works as
I would expect (Win x64 Py3.7.3, PyOpenGL 3.1.5).

Offhand, I am surprised that `glVertexAttribPointer(...)` would be the call
to fail; there are plenty of other GL calls that should have failed
beforehand, if indeed they didn't fail. GLFW creates a context, and it
looks like you're setting it as current. If that code does what it looks
like, correctly, then the error especially wouldn't make sense. I would
suggest to try validating the context, perhaps creating a debug context.

What happens if you just try drawing an empty window without the
problematic setup code? Also, why did you comment the context creation
hints?

Ian