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Keen 4-6: Fix for choppy scrolling on certain EGA/VGA cards

Posted: Fri Jun 16, 2017 20:41
by K1n9_Duk3
I'm not sure if this is the right place for this. I guess it should rather be posted on keenmodding.org, but I don't want to go through the hassle of creating a new account just for this.

I ran across a topic on the VOGONS forums called "Keen 4-5-6 choppy scrolling on EGA card". It was mentioned in the thread that Keen 4-6 have this issue, but Keen Dreams and BioMenace do not, so I assumed it would be possible to write a patch file for CKPatch to fix it. Further testing showed that the Keen 4 special demo doesn't have the scrolling issues on these cards, so I ended up using the code from that demo to patch the screen update code in Keen 4, 5 and 6. And it appears to work fine on these cards.

If you want to preserve the patch on keenmodding.org or extend the patch for other versions of Keen 4-6, or just want to try it on your old 286 (or whatever), feel free to do that. The patch files are attached to my post in the link above.

Re: Keen 4-6: Fix for choppy scrolling on certain EGA/VGA cards

Posted: Sat Jun 17, 2017 7:16
by Nisaba
(just reading your post. haven't tested anything yet. but going to, soon.)

interesting. I wasn't aware that there are Keen versions which work smoothly without that choppiness. thanks for sharing!

if you could, please post all information about this patch over at keenmodding.org as well. why, you might ask?! well, because it's the place where people would expect searching for tools and patches like this. I think it's a good idea bundle modding and patching related stuff over there.

Re: Keen 4-6: Fix for choppy scrolling on certain EGA/VGA cards

Posted: Sat Jun 17, 2017 20:34
by keenmaster486
BOOOOOM.

viewtopic.php?f=2&t=3662&sid=e7161d8270 ... f983ec3d56

THANK YOU FOR FINALLY IMPLEMENTING THIS