Re: [Glsdk-devel] GLE progress update

[Jason M. <ko...@gm...>]

StApostol wrote:
> > Windows defines its function entrypoints for the
> > stuff in gl.h, not as function pointers, but as live functions. I doubt
> > that wglGetExtension will work for them. So I'm not entirely sure how to
> > go about handling this part. Any suggestions?
>
> You are right regarding wglGetExtension not working with these 
> functions (or at least not consistently). To make matters worse, 
> different platforms expose different subsets dynamically, making 
> things tricky.
>
> Solution:
>
> 0. Define all signatures. Define static imports for all core functions 
> (i.e. versions 1.0-3.0). These are not exposed to the user.
>
> 1. Define all functions as function pointers. This is the public API.
>
> 2. Load each function dynamically (wgl/glx/aglGetAddress). If the 
> function pointer is *not* -1, 0, 1, 2 or 3 use it. If it is and the 
> function is core, use the relevant static export instead. Otherwise 
> "arm" the pointer with NULL.
>
> I am using this method in Tao/OpenTK with success. It works on all 
> platforms and is reliable.
>
Sounds good. I'll do that once I get the platform-specific stuff working.

BTW, I didn't get this e-mail until today. Something strange with the 
mailing-list server, perhaps?
>
> Notes:
>
> a. Some nvidia drivers return invalid function pointers (-1, 1, 2, 3), 
> so you have to take this into account.
>
> b. On windows, different contexts may return different function 
> pointers. This is normally not an issue, as it only happens between 
> different renderers (e.g. microsoft GDI and an accelerated context). 
> Still, I prefer to provide a "reload" function to the user in case 
> it's needed.
>
The load function already starts by clearing all of the function pointers.