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#41 Improve core support extension check.

open
nobody
None
5
2012-09-15
2011-01-07
No

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!

Discussion

  • Nigel Stewart
    Nigel Stewart
    2011-01-07

    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?

     
  • 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.

     


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