Precise rules for cave collapses?

[Traveller]

So I don't suffer through a lot more trial and error...  What's the specific rules on what will and won't collapse?

It looks like something resembling "any tile that was initially underground, and is not within six tiles of a natural or constructed wall", meaning that you can build an open room 10 tiles across safely--but not 11.

I've been using a lot of pillars in my wide open indoors kill-rooms, and they keep getting shot apart causing collapses.  Hoping that with better knowledge, I can build a sturdier one.  (Though I guess a better option is to just build it outdoors.)

[Lechai]

Every Roof tile needs to be within 6 tiles of a wall (natural or artificial) or it will collapse.
I'm pretty sure its 6, might be 7.

That being said, Ty said he is redoing how ceilings work, so it may change very soon

[Stormkiko]

I haven't done extensive testing on it, but from what I've found: As mentioned, wall can support a roof for five tiles, so pillars can be ten tiles apart. When you make a room, it supplies a thin metal roof. When you dig out an area you are left with a rock roof. This roof will either be thin, or thick. Any thin roof, rock or metal, that collapses will result in a loss of roof and a bunch of debris. A thick roof collapsing will drop rock down to support itself. Debris landing on a colonist severely injures them (70 or eighty points of damage I believe) whereas a thick roof dropping a pillar on them will kill them immediately.

[Tynan]

You guys are right, it just checks distance to closest support.

And while roofing is being redone, this won't affect how collapses work.

[Kender]

Any idea about the rule of opening a roof underground without collapsing? like the one in the figure, so one can put solar-panel inside mountain?

[nnescio]

So I don't suffer through a lot more trial and error...  What's the specific rules on what will and won't collapse?

It looks like something resembling "any tile that was initially underground, and is not within six tiles of a natural or constructed wall", meaning that you can build an open room 10 tiles across safely--but not 11.

I've been using a lot of pillars in my wide open indoors kill-rooms, and they keep getting shot apart causing collapses.  Hoping that with better knowledge, I can build a sturdier one.  (Though I guess a better option is to just build it outdoors.)

Roof tiles supported by a single pillar:



Supported tiles are in blue. The central wall is in gray. Note that the wall also supports a roof tile on top of it.

The cut-off point appears to be 6-tiles. Any roof tile that is at a 6-tile distance away or more from the nearest support will collapse. For diagonal distances, just apply the Pythagorean theorem.

(e.g. a roof tile that is 4 tiles to the east and 4 tiles to the north of a support pillar will not collapse as it is squareroot(4^2+4^2) = 5.66 tiles away from it, which is less than 6 tiles.)

Walls/Rock walls can support roofs as long as the latter are within the 'support' radius, even if they are not directly connected. This would appear to be a bug.

Example:



Also, sometimes, roofs will not collapse even if they are supposed to. This can happen when walls are mined/sold in a staggered order, 'though the roofs can still collapse at a later point when a farther wall is removed.

In any case, just ensure that each roof tile is supported by at least two walls, and your colonists should be safe enough.

Any idea about the rule of opening a roof underground without collapsing? like the one in the figure, so one can put solar-panel inside mountain?

You have to collapse the roof. Also, to create a skylight, you can only collapse "thin" rock roofs. Thick rock roofs will just drop an endless column of rock when collapsed.

Just ensure that the roof section you want collapsed is six tiles away from the nearest support. This should collapse it.

Example:



(Yeah, I overdid it a little. Note also that solar power panels don't have to be entirely in light to generate power. They will still generate power when at least half of the tiles they occupy are in sunlight.)

Also, as mentioned earlier, roofs will sometimes glitch and not collapse even if they are six tiles away from the nearest support. To avoid this, carve out the rock in square sections instead of in a diagonal/checkerboard/staggered fashion.

You guys are right, it just checks distance to closest support.

And while roofing is being redone, this won't affect how collapses work.

Is it possible for the roof collapse algorithm to check for contiguousness in the future? That is, a roof that isn't attached to a support by a series of adjacent roof tiles will still collapse, even if it's within the support radius of a wall. It kind of looks weird otherwise, as they are technically floating in midair.

Or does that consume too much CPU overhead?

[Spike]

What I found, by trial and error, is that you can have a max width of 10 tiles on one axis; as in, a 10x10 room dug out of the mountain will not have a collapse, nor a 10x20.  But if you turn it up to 11...

This has been from digging out in the hillside though, so I'm not sure about building in the open, or if it applies only for "thick rock roof" areas.