"Bleeding" self-referencing sectors

[Jodwin]

I guess a lot of people know of the trick of using self-referencing sectors to make invisible fences that can be jumped over. I've been toying with a map idea that would have such fences limiting player's movement but letting flying monsters get over them (so impassable lines are out of question). With the fences I ran into a weird (apparently nodebuilding) error which I had once heard about before: Depending on other map geometry, the self-referencing sectors might "bleed" to other sectors, effectively blocking things from moving. Here's a (greatly) simplified example:

In the image, the floor detail sector would cause a nodebuilding error, which in turn causes the self-referencing sector to bleed so that also the blue area would be blocking.

What I found with the map I'm playing around with, is that even small changes can have very unpredictable results: I had a ground detail, a pool of water, which caused a nearby fence to block on an extra 32x48 area or so. Both deleting the pool or moving it far away removed that particular bleeding, but caused an other self-referencing sector to bleed by a 256x64 area.

One solution that seems to work, is putting other self-referencing sectors around the fence ones, with floor level the same as the surrounding sector, something like this:

However, while it's working for now, I'm afraid that changing some random geometry somewhere else might break things again.

Does anyone know anything specific about this anomaly...and perhaps how to certainly prevent it?

[esselfortium]

It depends on your nodebuilder. Most of the nodebuilders that people use nowadays seem to be pretty lenient about self-referencing sectors, but if I remember correctly, ZenNode will only make them invisible (as desired) if their sector number is higher than that of the "solid" sector(s) that surround them.

Er, oh, nvm, I jumped to a conclusion and mistook your question for another one. In that case, I think your solution of putting another sector around it is probably the safest bet...:\

[Graf Zahl]

You always have to put self-referencing sectors into a properly closed area, i.e. surround them with other linedefs that have both sides in the containing sector. Without this it depends on the nodes where the self-referencing sector extends to. But such an outer boundary will serve as a barrier they can't cross.