I've asked this question on the SDL mailing list and got the following:
- This info from Sean Ridenour:
What happens in professional compositing
programs when using the standard over operation is this:
1. If the foreground image is premultiplied, go to step 3
2. Multiply the foreground image against its own alpha channel
3. Invert the foreground image's alpha channel
4. Multiply the background image (all channels) by the foreground image's newly inverted alpha channel.
5. Revert the foreground image's alpha channel to its original state
6. Add the foreground image to the background image (all channels)
- The pygame source code contains an alpha blit function.clicky
(Thanks Pete Shinners)
EDIT: Sabbac: I've tried to send you an email, but it didn't work
Just trying to be helpful.
Just some student from Germanyhttp://mitglied.lycos.de/xplosiff [edited by - randomZ on October 9, 2003 3:10:07 PM]