[SDL] CVS Update (alpha blending)

Sam Lantinga slouken at devolution.com
Tue Apr 4 22:20:41 PDT 2000


> The reason i would like to see DisplayFormat working fine with alpha
> channeled images, is not speed (anyway,i am using 32bit images on 32bit
> display :-) It's just that it's kind of awkward to keep a list of images
> with alpha channels and of those with no alpha and loading them using
> different ways (sometimes calling DisplayFormat and sometimes not).

I could return the same image in the case that no conversion is necessary,
but that would break a lot of code that does the following:

	converted = SDL_DisplayFormat(image);
	SDL_FreeSurface(image);
	...

SDL_DisplayFormat() performs the conversion by simply blitting the source
surface to a newly created surface that has the display pixel format.
The display format doesn't have an alpha channel, so the resulting
surface doesn't have an alpha channel.  In addition, the conversion blit
uses alpha blending.

Suggestions?

	-Sam Lantinga, Lead Programmer, Loki Entertainment Software



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