#41 Improve core support extension check.

[Christophe Riccio]

It would be great to improve the glewGetExtension implementation to support OpenGL 3 core profile as it is really simple.

if OpenGL version < 3.0
use old implementation
else using the new method:
GLint n, i;
glGetIntegerv(GL_NUM_EXTENSIONS, &n);
for (i = 0; i < n; i++)
printf("%s\n", glGetStringi(GL_EXTENSIONS, i);

Thanks!

[Nigel Stewart]

See also ID: 2835552 (Feature Request)

Is it still useful for Core context purposes to take this first step?
Or is it just going to annoy people to not go the whole mile?

[Christophe Riccio]

The first step? If you say first step for the current glewGetExtension implementation then its not what I meant.

The idea is that there are 2 ways to check extensions : glGetString(GL_EXTENSIONS); for OpenGL 2.1 and glGetStringi(GL_EXTENSIONS, i) for OpenGL 3 >

glGetString has some issues that lead the ARB to deprecated it when use with GL_EXTENSIONS. There is no alternative ways with OpenGL 2.1 so that it has to be used.

With OpenGL 3.0 we now have glGetStringi(GL_EXTENSIONS, i) which is the only valid function for OpenGL core profile and I think it's quite wise to use it for all OpenGL 3 > versions.

Checking the OpenGL version is quite easy:
glGetIntegerv(GL_MAJOR_VERSION, &MajorVersionContext);
glGetIntegerv(GL_MINOR_VERSION, &MinorVersionContext);

But GL_MAJOR_VERSION and GL_MINOR_VERSION are only OpenGL 3.0 values I think.

Checking if glDrawElementsInstanced is null should be a reliable way to check if the OpenGL context is an OpenGL 3.0 > context.

For people is make no change, they will still use glewGetExtension the same way except that is will work we core profile unlike currently.

[Nobody/Anonymous]

Yeah fixing that INVALID_ENUM error would be cool :)

[Nigel Stewart]

See also:
https://github.com/nigels-com/glew/pull/24

[Nigel Stewart]

Fixed in the upcoming 2.0.0 release of GLEW,