[SDL] Alpha revisit

Joel Chen jchen at interval.com
Tue Jul 9 15:28:01 PDT 2002


hmmm...., I guess it's pushing it to ask about combining surf and pixel
alpha (ie. apply surf alpha, and then pixel alpha) then.  

Basically I've got my hands tie here because I need to display a RGBA
surface at 50% and I am trying to see if there's any hoops I can jump
through with what current SDL has to achieve it.  I can't transfer it to RGB
surf because I would lose the pixel alpha, which is important.

OpenGL is out of the question.

<sigh> so far, the only way I've came up with is to lock the surface and
modify the alpha values myself and then reload my data after I am done.


> -----Original Message-----
> From: DrEvil [mailto:drevil at warpcore.org] 
> Sent: Tuesday, July 09, 2002 2:21 PM
> To: sdl at libsdl.org
> Subject: Re: [SDL] Alpha revisit
> 
> 
> On Tue, 2002-07-09 at 15:51, Joel Chen wrote:
> > The more I work with SDL the more I realize how limited the 
> way SDL handles
> > alpha is.  It would've been nice if I can explicitly 
> specify alpha off, surf
> > alpha, or channel alpha.  Couple with limited or 
> differently behaving
> > hardware, this can get very frustrated and sometimes 
> helpless at achieving a
> > certain effects.  
> > 
> > Bottom line, was there some sort of technical reason, like 
> too difficult to
> > implement, for this?
> 
> I think portability. Many platforms do not feature some of the alpha
> capabilities you're asking for to my knowledge. Would someone more
> knowledgeable comment / correct me?
> 
> 




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