[AD] alpha blending in new GFX API

[Milan Mimica <milan.mimica@xxxxxxxxxx>]

The short question: Will alpha blending will available in color depth
lower then 32-bit?


How I see it in http://allegro.dotsrc.org/future/gfx-api.txt, the
programmer won't be able to create a RGBA bitmap in 16-bit color depth
(or any other lower then 32-bit mode). The only assumption I'm making is
that al_create_display_bitmap() will fail with other then desktop's 
color depths on platforms that not allow changing color depth on the 
fly, like X11.

Bitmaps created with al_create_bitmap() inherit color format from the
parent. Hence, you can only create video bitmaps with the same color
format as the display bitmap. You see the problem? No way to create a 
RGBA video bitmap. No way to do hardware accelerated blending in 16-bit 
mode. OpenGL does allow that.

Allegro 4.2.1 + AllegroGL suffers from the same design problem. I was
looking if I could implement alpha blending in AGL, but couldn't because 
I cannot run my X server in 32-bit color depth.


--
Milan Mimica
http://sparklet.sf.net