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A&A palette bug

Posted: Wed 19 Jul, 2017 9:04 pm
by leilei
In Amulets & Armor (any version) the brighter colors of the palette get malformed into being even brighter and oversaturated as if it were posterized to a lower bpp. There's occasional blips of intact frames during screen changes where the palette is intact. The game's built-in gamma correction (Alt-F10) and fading routines also affects these new malformed colors.

Seems to happen on anything with VGA. Occurs on interpreter too.

Re: A&A palette bug

Posted: Thu 03 Aug, 2017 6:39 pm
by omarsis81
Is this how it looks to you?
Rather than oversaturated, it looks as if it was EGA, but of course a game from 1996 it doesn't even support that card

DOSbox vs PCem latest commit
dosbox.png
dosbox.png (213.82 KiB) Viewed 7740 times
aa_pcem.png
aa_pcem.png (129.04 KiB) Viewed 7740 times

Re: A&A palette bug

Posted: Thu 03 Aug, 2017 8:04 pm
by leilei
Yep.

And since the game's been open sourced, this file might provide a clue.

Re: A&A palette bug

Posted: Fri 04 Aug, 2017 1:23 pm
by Battler
Looks to me like the palette indexes might be off by 1 - look at the red blocky cursor under "Character Name".

Re: A&A palette bug

Posted: Fri 04 Aug, 2017 1:25 pm
by omarsis81
Battler wrote:Looks to me like the palette indexes might be off by 1 - look at the red blocky cursor under "Character Name".
The big question would be: why only happens in this game?

Re: A&A palette bug

Posted: Fri 04 Aug, 2017 1:41 pm
by Battler
I remember that on the MAME forum, someone once wrote a (S)VGA sequencer test, that on real hardware, would under some conditions, sequence the colors off by one. I tested it in PCem, and it didn't do that. If this game sets up the sequencer mode that way, it could explain why this happens.

Re: A&A palette bug

Posted: Fri 04 Aug, 2017 9:21 pm
by SarahWalker
Fixed in rev 831.

Re: A&A palette bug

Posted: Fri 04 Aug, 2017 11:29 pm
by omarsis81
leilei: you owe me one for resurrecting this thread ;)

Re: A&A palette bug

Posted: Mon 14 Aug, 2017 8:24 pm
by StefanDD
Hello all, I just joined the forum today to post about the subsequent issue, and it may, by coincidence, be related to the one discussed here. In both Weltenschmiede text adventures "Die Kathedrale" and "Hexuma", the palette looks corrupt. This does not at all depend on the choice of main board, CPU speed, video bus speed, or video card. Here it is shown for a more modern configuration but also happens on an old IBM AT with VGA adapter.
VGA palette bug.png
VGA palette bug.png (215.25 KiB) Viewed 7497 times

Re: A&A palette bug

Posted: Mon 14 Aug, 2017 10:04 pm
by omarsis81
StefanDD wrote:Hello all, I just joined the forum today to post about the subsequent issue, and it may, by coincidence, be related to the one discussed here. In both Weltenschmiede text adventures "Die Kathedrale" and "Hexuma", the palette looks corrupt. This does not at all depend on the choice of main board, CPU speed, video bus speed, or video card. Here it is shown for a more modern configuration but also happens on an old IBM AT with VGA adapter.

VGA palette bug.png
Did you test PCem with the latest commit? or stock version 12?

Re: A&A palette bug

Posted: Mon 14 Aug, 2017 10:06 pm
by StefanDD
omarsis81 wrote:Did you test PCem with the latest commit? or stock version 12?
I have unfortunately not set up a build system for the Windows version, so I am just using the v12 stock from February.

Re: A&A palette bug

Posted: Mon 14 Aug, 2017 10:10 pm
by omarsis81
StefanDD wrote:
omarsis81 wrote:Did you test PCem with the latest commit? or stock version 12?
I have unfortunately not set up a build system for the Windows version, so I am just using the v12 stock from February.
Because the bu from A&A was fixed, but of course was much after February. I test the game with the latest commit if the recent fix also applies to these games

Re: A&A palette bug

Posted: Mon 14 Aug, 2017 10:31 pm
by StefanDD
omarsis81 wrote:Because the bu from A&A was fixed, but of course was much after February. I test the game with the latest commit if the recent fix also applies to these games
I'd appreciate that!

Re: A&A palette bug

Posted: Mon 14 Aug, 2017 11:58 pm
by leilei
Battler wrote:Looks to me like the palette indexes might be off by 1 - look at the red blocky cursor under "Character Name".
FTR this is incorrect and wrongly interpreted from two different frames of palette ramp cycling.

Re: A&A palette bug

Posted: Tue 15 Aug, 2017 7:46 pm
by omarsis81
I confirm Hexuma works fine with the latest commit

Re: A&A palette bug

Posted: Tue 15 Aug, 2017 7:51 pm
by StefanDD
Fantastic - Thanks for testing this!