[alpha blending in hardware]

Hello!

I think that SDL support alpha blending in hardware surfaces but… I
testing in Windows 2000 with GeForce4 4200, Ati Radeon 7500 and Matrox G200
and not support alpha blending in hardware, if video surface is in video
memory the alpha blending is VERY SLOWLY (it is by download surface from
video memory to system memory and CPU do alpha blending and upload again to
video memory).
But I think that DirectX Draw have support to alpha blending in hardware…
why SDL not support it? it’s Windows2000? or video cards than I testing?
And the real question is… how to do alpha blending when surfaces is in
video memory?, I think in write a function than download using MMX and do
alpha blending with MMX too but… SDL can do it auto?

Sorry by my bad english… and thanks you!

Robert_________________________________________________________________
Charla con tus amigos en l?nea mediante MSN Messenger:
http://messenger.microsoft.com/es

Roberto Prieto wrote:

But I think that DirectX Draw have support to alpha blending in
hardware… why SDL not support it?

Because you’re wrong… DirectDraw never implemented hardware alpha
blending in 2D as far as I am aware, up to and including DX7. This is
because most video cards don’t support it for 2D graphics. There is a
flag for it in DirectDraw but it does nothing. Sorry. :)–
Kylotan
http://pages.eidosnet.co.uk/kylotan

Ok! thanks you :), I never used DirectDraw only read a bit of documentation.

And now… as it is the best way(and fastest) to do alpha blending with
surfaces in video memory? Do you know it?

I go to see your web…

good bye!

Robert

Roberto Prieto wrote:
But I think that DirectX Draw have support to alpha blending in
hardware… why SDL not support it?

Because you’re wrong… DirectDraw never implemented hardware alpha
blending in 2D as far as I am aware, up to and including DX7. This is
because most video cards don’t support it for 2D graphics. There is a
flag for it in DirectDraw but it does nothing. Sorry. :)_________________________________________________________________
?nete al mayor servicio mundial de correo electr?nico:
http://www.hotmail.com

Roberto Prieto wrote:

And now… as it is the best way(and fastest) to do alpha blending with
surfaces in video memory? Do you know it?

OpenGL… (or Direct3D, if you’re not bothered about portability).–
Kylotan
http://pages.eidosnet.co.uk/kylotan

Roberto Prieto wrote:

And now… as it is the best way(and fastest) to do alpha
blending with

surfaces in video memory? Do you know it?

OpenGL… (or Direct3D, if you’re not bothered about portability).

Call SDL_GetVideoInfo to see whether hardware alpha is accelerated.
If it is, good for you. If it is not, do alpha blending on a
software surface and blit that surface to the screen instead.–
Matthijs Hollemans
All Your Software
www.allyoursoftware.com

Ok, then I do alpha blending in system memory and blit to screen :).
Is the first time than I use this mail list and I can’t is more happy!! :),
thanks you to all by reply to question and Sam for the best multiplatform
library!!

See you! good by_________________________________________________________________
MSN. M?s ?til Cada D?a http://www.msn.es/intmap/