Re: [AD] OpenGL

[Jerry <crashfourit@xxxxxxxxxx>]

I like this idea better:

   display = al_create_display(..., AL_ACCELERATED, ...);
   bmp = al_get_buffer(display);
   al_clear_bitmap(bmp, 0,0,1,1); // or whatever colour format
    al_flip_display(display);


I would rather have a clean implementation of the drivers than a bunch 
of hacks all over the place. The first line could be like

   display = al_create_display(..., AL_ACCELERATED_GL, ...);

Or...

   display = al_create_display(..., AL_ACCELERATED_DX, ...);

for specific accelerated drivers.

I would also recommend to abstract what 3D functions that allegro offers 
and add them to the driver table so they could be accelerated too.

Robert Ohannessian wrote:
> >  I would hide any refence to OpenGL and use a dummy `bitmap':
> >     
>
> AGL already provides you with this ability (well, to the limited extent
> of the vtable entries we implemented).
>
>
>   
> > -----Original Message-----
> > From: alleg-developers-bounces@xxxxxxxxxx [mailto:alleg-
> > developers-bounces@xxxxxxxxxx] On Behalf Of Evert Glebbeek
> > Sent: Tuesday, July 25, 2006 7:03 AM
> > To: Coordination of admins/developers of the game programming library
> > Allegro
> > Subject: Re: [AD] OpenGL
> >
> > On Tuesday 25 July 2006 13:44, Elias Pschernig wrote:
> >     
> > > Does it seam feasible to somehow merge in all of AllegroGL, just so
> > >       
> we
>   
> > > have working OpenGL again in 4.3, and then worry about refining this
> > >       
> to
>   
> > > a new graphics driver structure later?
> > >
> > > Or is it maybe better to start a clean OpenGL driver from scratch?
> > >
> > > The former probably would be rather messy, but once it compiles,
> > >       
> would
>   
> > > mean we get all the features already in AllegroGL. The latter means,
> > > we'd initially start with only a minimal implementation, and then
> > >       
> would
>   
> > > need to add the required features again step by step (probably
> > >       
> peeking
>   
> > > at the AllegroGL code).
> > >       
> > What I would prefer in terms of the graphics drivers is to change the
> > existing
> > vtables now and adapt the code to use the new drivers.
> > The real problem I had with that (which I brought up before and was
> > discussed,
> > without reaching some final consensus) is that right now, changing the
> > graphics drivers will break all other drivers on all other platforms.
> >     
> Now
>   
> > maybe we should just Not Care and allow things to break and then fix
> >     
> them
>   
> > later.
> >
> >     
> > > What I expect in the end is, that I simply can do:
> > >
> > > display = al_create_display(640, 480, AL_AUTODETECT, AL_OPENGL);
> > > glClearColor(0, 0, 1, 1);
> > > glClear();
> > > al_flip_display(display);
> > >       
> > I would hide any refence to OpenGL and use a dummy `bitmap':
> >
> > display = al_create_display(..., AL_ACCELERATED, ...);
> > bmp = al_get_buffer(display);
> > al_clear_bitmap(bmp, 0,0,1,1); // or whatever colour format
> > al_flip_display(display);
> >
> > that way, code can be written with complete ignorance of the
> >     
> underlying
>   
> > driver
> > and work properly. Sure, one can still use the normal OpenGL commands
> >     
> (and
>   
> > we
> > must make sure that this does work), but the second example should
> >     
> work
>   
> > too.
> >
> > In case of OpenGL, the returned bitmap from al_get_buffer could just
> >     
> have
>   
> > a
> > flag set to say `use OpenGL commands instead of drawing to me', or
> >     
> better
>   
> > yet, the drawing operations in the vtable could be directly mapped to
> > OpenGL
> > commands:
> >
> > al_clear_bitmap(bmp, ...) gets translated to
> > bmp->vtable->clear(bmp, ...);
> > which is a reference to
> > al_opengl_clear_bmp(BITMAP *dummy, ...)
> > {
> >    glClearColor(...);
> >    glClear();
> > }
> >
> >     
> > > Each graphics driver would have a capability flag telling if it can
> > > provide an OpenGL context or not. And graphics drivers would see in
> > > their initialization function if OpenGL is requested, and initialize
> > >       
> an
>   
> > > OpenGL context if so.
> > >       
> > I think a generic AL_ACCELERATED flag would be better. Internally it
> >     
> would
>   
> > work as you describe anyway.
> >
> > Evert
> >
> >
> >     
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