[osg-users] GL3: non-GL3 version number: 1.0

[Robert Osfield]

Hi Maxim,

On 13 October 2017 at 15:36, Maxim Stere <osgforum at tevs.eu> wrote:

> Ah, interesting...I did not know that GL3 Profile in OSG was only for MAC
> compatibility. That is good to know.
>

It's not purely for MacOS compatibility, building the OSG with cmake .
-DOPENGL=GLCORE can be used on all platforms, and is used where you don't
want any of the fixed function capabilities of old GL


>
> Default Windows GL headers are of the old 1.1 version. So the advanced
> later versions might be handled by the graphics card.
>

The OSG queries all extensions at runtime and provides fallbacks from
elements missing from header so even if you compile against a GL 1.1 header
it'll be able to use later features.



> So in GL2 profile, will OSG be able to use GLSL 4.5 Core version?
>

 If you explicitly want to exclude compatibility profile then you'll want
to build the OSG with GLCORE, but otherwise the OSG will treat GL as both
forward and backwards compatibility - as long as the driver supports it.
In the case of GL3 under OSX they drop all compatibility profile
functionality so you have no choice.

Robert.
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