[PyQt] Expose QOpenGLContext::getProcAddress?

[Georg Brandl]

Am 13. April 2019 14:00:39 MESZ schrieb Phil Thompson <phil at riverbankcomputing.com>:
>On 13 Apr 2019, at 3:33 pm, Georg Brandl <g.brandl at fz-juelich.de>
>wrote:
>
>> On 12.04.19 22:55, Phil Thompson wrote:
>> On 12 Apr 2019, at 10:49 pm, Georg Brandl <g.brandl at fz-juelich.de>
>> wrote:en thou
>>
>> Hi,
>>
>> for integrating a PyQt application with OpenGL drawing in an
>> extension module written in another language, it would be useful to
>> have this method exposed in the QOpenGLContext class.
>>
>> It is already exposed in the legacy QGLContext class, and I can use
>> that for now, but from the docs it sounds like the QGL classes
>> should not be used anymore.
>> Just because it is exposed doesn't mean it is useful. As I understand
>> it it returns the address of a C function wrapped as a sip.voidptr.
>> Is that useful?
> Yes, that's what it does.  It seems that the OpenGL library is usually
>loaded at runtime by some helper library, and individual functions are
>resolved with dlsym.  That way, applications can react to various
>functions and extensions being available or not.
>
>Qt has it in the QOpenGLContext class, and for example, PyOpenGL
>does it via ctypes.  Other GL helper libraries like GLFW have them
>as well:
>https://www.glfw.org/docs/latest/group__context.html#ga35f1837e6f666781842483937612f163
>
>My drawing code, being written in Rust, also depends on a function
>that resolves the functions at runtime.  Since I'd like to make sure
>that the functions are resolved in the same way that Qt already does
>for the calls it makes internally for the widget, I'd like to pass
>QOpenGLContext::getProcAddress to it, via a Python callback function.
>
>I understand how it is supposed to work but PyQt doesn't support the
>calling of arbitrary addresses even though the inclusion of
>getProcAddress() might suggest otherwise.

That doesn't matter for my case, I don't need to call the function pointer from Python. Just need to pass it down to the Rust code, which knows how to use it. As I said, it works fine with the equivalent method on the legacy class.

Best,
Georg

--
Dipl.-Phys. Georg Brandl
Forschungszentrum Jülich - JCNS
Lichtenbergstraße 1
D-85748 Garching
Tel: +49 89 289 12131
Fax: +49 89 289 10799


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