[r1157] Empty Subsectors

[NeuralStunner]

I'm finding subsectors that are completely empty, having no planes and showing sky through them. I tried several things:

- Remakingthe map with smaller sectors.
- Disabling all the 3D floors in the map.
- Rebuilding the nodes externally with ZDBSP.
- Deleting the ZNodes lump from the wad.
- Turning on GenNodes in GZDoom.

ZDoom does not have this glitch.

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I managed to get this numerous times with the same map. My most recent attempt at splitting down sectors just moved the empty space somwhere else.

Map is attached. (Heretic E1M1. Uses the Baker's Legacy pack, but the hole shows the same without it.)

[Gez]

Also happens in r1126.

But the really weird thing is that when I try to load it in an old build of mine that is full of debug commands, I get spurious error messages telling me it has no namespace and that there is an unexpected character on line 1. WTF?


Apparently, this sector trips up one of the hack detection mechanisms and gets told that it has one-sided walls. Which of course isn't true. There is something weird going on.

PS: Whatever the issue is, it's not caused by any recent change. I get the same bug in 1.4.8.

[NeuralStunner]

Perhaps this is a bug in ZDBSP's generation of GL Nodes?

[NeoHippo]

I moved the control sectors



and the 'hole' was gone.

[NeuralStunner]

Not gone, it just moves elsewhere. (Namely, on the surrounding ledge.)

I didn't even have them beyond the 11,000 "safe" mark... So I don't see why that should make a difference, other than maybe getting the BSP tree to be built differently.

[Gez]

I managed to remove the hole by merging most of the identical sectors in the middle ring and deleting the corresponding linedefs, but depending on your plans for that map that may not be a good workaround.

[Graf Zahl]

This still needs a proper analysis.
In general to prevent control sectors from messing up a map it might be a good idea to move them out of the actual map area both in x and y direction. Otherwise they can force additional splits of the geometry which increases the risk of node errors.

[NeuralStunner]

I managed to remove the hole by merging most of the identical sectors in the middle ring and deleting the corresponding linedefs, but depending on your plans for that map that may not be a good workaround.

I originally had it built that way, but I was getting empty subsectors in the outer rings. That's what prompted me to slice the map into so many smaller sectors, hoping it would help the nodebuilder a little.

In general to prevent control sectors from messing up a map it might be a good idea to move them out of the actual map area both in x and y direction.

How do you mean? I try keep them out of my way when mapping, although putting them at the farthest possible distance (-32768,32767) gave me this:

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This may not be surprising.

After deleting the control sectors entirely, it seemed as if all was well at first, but after looking a while I found another hole on one of the raised areas.

But it's interesting, the errors always seem to appear in the northwest (-,+) quadrant of the map. So I moved the control sectors to the southeast (+,-) and couldn't find a single gap.

I was also able to copy the geometry whole into a Hexen format map, and it displayed without errors. The vertex cordinates all being whole integers, I wonder if that makes this a math issue.

[Graf Zahl]

I know that ZDBSP has some issues. There's still the open thread about one map in ZPack causing the engine to freeze. I wouldn't be surprised if this is somehow related to the precision issues with the vertex picker.

[wtg62]

I hate this bug because it can affect clipping.