Weird black marks on flats

1 hour ago, DoomLover234 said:

I'm making some flats for a Doom mod, and I started doing a little bit of test flats, like full black squares, full brown squares etc. It works excellent in FireAlpaca where I made them (no marks whatesoever), and in XWE there seems to be no problems. However when I launch Doom, there are some weird black marks that look like dashes. They only appear in what seems to be the bottom left corner. Does anyone know the cause of that?

Make sure that your flats are in flat format, not patch format. A 64x64 flat should be exactly 4096 bytes.

Doom (and many source ports) have problems in the code that renders floors / ceilings. If you make a new flat texture and put it in a single 64x64 test sector that is the same height as the sector next to it, the renderer for whatever reason (that I should actually pin down one of these days) gets confused at the edge of the sector and ends up drawing a "seam" for some reason. This is probably best known from the teleporter at the end of E1M8 where you can see seams on the edges of the 4 individual flats.

This is the problem in action. Pay attention to the floor and ceiling. And don't ask me why I'm remaking Doom flats MS Paint style.

also, yes. They are all proper flats.

Have you tried importing them in SLADE? XWE is very old and no longer supported, and does a lot of weird things.

I would have done so in SLADE but I can't install it because it needs some runtime I cannot install because I cannot properly deinstall a different version of the same runtime. I'll try it again though. XWE never gave me problems until this, even with enemy sprites.

Could you make a test wad having just one flat (such as that FLOOR1_1), check if the marks still appear in Doom and post it in here? 

48 minutes ago, DoomLover234 said:

I can't install it because it needs some runtime I cannot install because I cannot properly deinstall a different version of the same runtime.

In general those do not need removal of the old versions. Just install the new one. (Unless there're other reasons not to.) XWE is unsupported but IMO it plays fine even on modern 64-bit system when run on admin rights.
 

3 hours ago, DoomLover234 said:

also, yes. They are all proper flats.

I'm still inclined to think they're actually not, as I remember having a similar problem a long time ago. Check if all 3 of these things really apply:

1. Size of the flat is exactly 64x64.

2. The flat lump is between the flat markers.

3. The flat graphic is not in the standard Doom graphic format, but in the flat format.

Assuming you're using GZDoom or something, nearly identical spots (though much smaller) appear on all of the flats when using the high quality resize texture mode. No idea if you have that on but it's worth noting.

Would help if you post the actual flats in their original form.

9 hours ago, DoomLover234 said:

I would have done so in SLADE but I can't install it because it needs some runtime I cannot install because I cannot properly deinstall a different version of the same runtime. I'll try it again though. XWE never gave me problems until this, even with enemy sprites.

Just run a pc update and it will automatically install the runtime that you need. It worked for me. 

9 hours ago, scifista42 said:

3. The flat graphic is not in the standard Doom graphic format, but in the flat format.

How do you check that? (in XWE)

Also, I'll try a solution of my own.

EDIT: OK, I fixed the problem my starting from scratch :D. My assumption is that, when I added about 15 new flats last time, I forgot to immediately save them as Doom flats. I think I've remembered that and opened the WAD again to check but they were already Doom flats. So, when I closed the WAD after importing the flats, XWE must've saved it as a Doom flat in whatever corrupt format it did. So the key to non-glitchy flats is simply saving each flat as a Doom flat immediately when you replace it.

Also make sure your texture format is the default. For me I get weird results using other formats from within GZDoom.