Re: OpenGL context without AppKit

[Niels Grewe]

Am 01.02.2012 19:52, schrieb Ivan Vučica:
> 
> 
> On Sat, Jan 28, 2012 at 22:06, Niels Grewe <address@hidden
> <mailto:address@hidden>> wrote:
> 
>     > Hi,
>     >
>     > definitely. I'm counting on supporting GLES. I'm not sure it's
>     sensible
>     > to target solely GLES. Most (if not all) of CoreAnimation code will be
>     > shared between GL and GLES, and creation of the context is platform
>     > specific, anyway, isn't it?
>     >
>     > GLES support on desktops will be flaky at best, missing at worst (see
>     > Win32). Targeting both GL and GLES is not difficult.
>     >
>     > Am I wrong? :-)
> 
>     No, you're quite right :-) The point about EGL is that it's not tied to
>     OpenGL-ES or any specific windowing system.
> 
> 
> Unfortunately, upon further examination, it seems that this is not
> correct: EGL is solely for creating OpenGL ES contexts, not for creating
> OpenGL contexts. See, for example:
>  
> http://stackoverflow.com/questions/7017239/what-are-the-relations-between-egl-and-opengl

That's not quite correct. Since v1.4 EGL also specifies how to support
plain old OpenGL. Whether it's actually supported is up to the
implementation though. But the mesa implementation of EGL supports it
and that's probably what we care about on the desktop. Check out the
examples at:

http://cgit.freedesktop.org/mesa/demos/tree/src/egl/opengl

Also, you don't create Open(GL|GLES|VG) contexts explicitly with EGL.
You bind the client APIs you want to EGL and create an EGLContext that
you'll use instead.

Cheers,

Niels