Alpha blit question

[Sam Lantinga <slouken@devolution.com>]

When implementing a source alpha blit, is it better in general to use
a separate alpha surface (faster in software) or extract the alpha 
information from each pixel (faster in hardware) ?

Hardware accelerated 2-D alpha blending is very rare at the moment.

Also, the semantics of the source alpha value are:

	As alpha goes up, the amount of the source blended goes down.

right?
(I thought real alpha was a measure of opacity, not transparency)

See ya!
	-Sam Lantinga				(slouken@devolution.com)

--
Author of Simple DirectMedia Layer -
	http://www.devolution.com/~slouken/SDL/
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