Re: Re: [Linux-fbdev-devel] Redesign of kernel graphics interface

["Ville Syrjälä" <syrjala@sci.fi>]

On Fri, May 14, 2004 at 11:40:04AM -0700, Jon Smirl wrote:
> --- Ville Syrjälä <syrjala@sci.fi> wrote:
> > > I said OpenGL is the only accelerated API available on Linux. Can you name
> > > another?
> > 
> > DirectFB.
> 
> Does DirectFB work on anything beside Matrox now?

It works on any card with a working fbdev driver (vga16fb excluded). 
Hardware acceleration is available on quite a few chips these days.

ati128  cyber5k  mach64  neomagic  nvidia  savage  tdfx
cle266  i810     matrox  nsc       radeon  sis315

That's the list of drivers in DirectFB cvs. Plus there is at least one 
driver outside the DirectFB tree.

I use matrox and mach64 drivers daily. It's been a few years since I 
seriously used XFree86.

> > > There is a little acceleration in framebuffer, but I don't know of any
> > > others. Also, software mesa works just fine to provide OpenGL on dumb 2D
> > cards.
> > 
> > Using unaccelerated OpenGL for 2D rendering doesn't sound exatly useful. 
> 
> There is much more to 2D rendering in things like the Mac UI and Longhorn than
> can be accomplished with BitBlt. You need transforms, filters and alpha
> blending. Hardware texturing is much faster than doing it in software. Some of
> the effects are achieved with pixel shaders. xserver features a fully composited
> window manager, it needs these features to have a fast response time.
> 
> OpenGL to me seems like the best pick for these reasons:
> 1) with have a good open source version, mesa
> 2) mesa supports a broad number of cards, basically everything there is doc for

Just about as broad as DirectFB.

> 3) OpenGL is a well published API, it is taught in universities and many books
> are available
> 4) It is likely that Nvidia and ATI will support standalone OpenGL stacks for
> their high end hardware on Linux
> 5) OpenGL is cross-platform. For example Cairo is being written with an OpenGL
> back end. OpenGL Cairo will run on Window and the Mac too. This will make Linux
> apps more portable.
> 6) The embedded market has OpenGL-ES which can run in less than 100K.
> 
> What would be reasons for picking another API?

DirectFB is good for a few reasons:
- Input handling
- Easy access to hardware overlays
- YUV formats
- Ease of porting DirectX applications
- Good acceleration
- Easy API / personal preference

I'm not suggesting that everyone start using DirectFB. Everyong should be 
able to use any API they want. The kernel should provide just enough to 
allow these APIs to be implemented.

-- 
Ville Syrjälä
syrjala@sci.fi
http://www.sci.fi/~syrjala/


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