On Mon, 04 Aug 2008 13:02:00 -0700, David O'Toole <[EMAIL PROTECTED]> wrote:

> Hi Luke,
>
> Upgrading to the latest svn fixed my problem. Thank you.
>
> Note that sdl-image:load-image accepts a :surface-alpha parameter,
> not :channel-alpha, so I could not fully try your suggestion below when
> making surfaces from PNG files. (Supplying :surface-alpha t did not help
> with the old version---only upgrading to svn seems to have fixed it.)
> Also in some spots the docs say that a function will accept
> sdl-src-alpha as a flag, but then the corresponding function doesn't
> accept flags (for example set-alpha), and the docs don't quite seem in
> sync with the situation.

I need to type up a description of how lispbuilder-sdl handles surfaces.  
Here is a short description of the :SURFACE-ALPHA, :CHANNEL-ALPHA and  
:ALPHA flags.

:ALPHA - Deprecated. Don't use anymore.

:SURFACE-ALPHA - Sets SDL_SRCALPHA as well as the SDL_Surface alpha value.

:CHANNEL-ALPHA - Sets the alpha mask for the pixels of a SURFACE (the A of  
RGBA).

However reading through SDL_SetAlpha it seems that we should allow setting  
the SDL_Surface alpha value, without mandating that SDL_SRCALPHA is also  
set.

I need to figure out how to do this without breaking everything. I'll  
probably add a :SRCALPHA keyword which will default to T if :SURFACE-ALPHA  
is set, but can also be explicitely set to NIL.

- Luke
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