A minor graphic bug when scrolling in level editor

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Zomis
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A minor graphic bug when scrolling in level editor

Post by Zomis »

Take a look at this picture:
http://www.zomis.net/rnd/download.php?id=659

You should especially take a look at the map positions above the walls. There, on all the fields left of the sand there's a vertical green-ish line at the left of the empty fields. And a vertical yellow line at the left of the wall fields.

This happened to me when I created a level with some sand lines, and scrolled left in the map editor. Scrolling up, down and right works fine. But after scrolling right so that you scroll past the wall when you start scrolling right, then you will notice this graphic bug.

I also just noticed that it's possible to create a blue graphic bug of the same type when clearing all graphic bugs by scrolling up/down and then scrolling left (without scrolling right).

I hope you will be able to reproduce at least one of these occations.
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Holger
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Post by Holger »

I have also noticed this effect when playing (but it is already fixed in the last pre-release version).

It seems that this has something to do with using the current SDL version on Windows -- the problem seem to not appear on Linux, and also seem not to appear with the SDL version from the last official R'n'D release. It looks like there was a bug introduced into SDL that makes (visual) problems when blitting overlapping bitmaps. I have worked around this problem inside the game (which makes scrolling noticeably slower on slower systems), but not yet in other parts of the game (like in the editor).

This is something that I should investigate further, and that may lead to a bug report on the SDL mailing list if it really turns out to be a problem with the new version of the SDL library on Windows, which I have to check before.
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Holger
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Post by Holger »

Fascinating! The above observations were done with R'n'D 3.2.3 and SDL 1.2.11, a combination which shows the bug described above.

Apparently, this problem has been fixed with SDL 1.2.12, although I can't see any hint about it in the ChangeLog on www.libsdl.org. (Of course, I have found this out after I fixed this issue for all blits that copy from and to the same bitmap, where the problem occured.)

So it seems that this problem is fixed now by delivering R'n'D with the new SDL 1.2.12 (also delivered with 3.2.4).
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