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Bug 848 - SDL_SetAlpha broken with alpha 128
Summary: SDL_SetAlpha broken with alpha 128
Status: RESOLVED FIXED
Alias: None
Product: SDL
Classification: Unclassified
Component: video (show other bugs)
Version: 1.2.13
Hardware: x86 Linux
: P2 minor
Assignee: Ryan C. Gordon
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2009-10-15 14:45 UTC by Ivo Danihelka
Modified: 2009-10-16 07:28 UTC (History)
0 users

See Also:

Attachments
Screenshot with alpha 128. (342.35 KB, image/png)
2009-10-15 14:45 UTC, Ivo Danihelka 		Details
Screenshot with alpha 129. (316.09 KB, image/png)
2009-10-15 14:46 UTC, Ivo Danihelka 		Details
View All Add an attachment (proposed patch, testcase, etc.)

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Description Ivo Danihelka 2009-10-15 14:45:04 UTC 
Created attachment 418 [details]
Screenshot with alpha 128.

SDL_SetAlpha works fine with alpha 127 or 129.
It produces strange colors with alpha 128.
The problem started after upgrading to Ubuntu Jaunty (libsdl1.2debian
1.2.13-4ubuntu3).

The produced colors are not stable. It seems like if they are taken from an
uninitialized variable or something like that.
See the attached a screenshot with alpha 128 and alpha 129.

I noticed that another developer also met it:
http://lists.libsdl.org/pipermail/sdl-libsdl.org/2009-August/071819.html


What info would be helpful to provide?
Thanks.
Comment 1 Ivo Danihelka 2009-10-15 14:46:11 UTC 
Created attachment 419 [details]
Screenshot with alpha 129.
Comment 2 Sam Lantinga 2009-10-15 20:31:56 UTC 
I believe this has been fixed with the current SDL snapshot:
http://www.libsdl.org/tmp/SDL-1.2.zip

Can you try it out?

Thanks!
Comment 3 Ivo Danihelka 2009-10-16 02:25:39 UTC 
The tried SDL-1.2.14 does not the problem.
Thanks.
Comment 4 Sam Lantinga 2009-10-16 07:28:39 UTC 
Great, thanks!