[X:CE 0.34.2] - entire stadium collapsed!

[birds_and_trees]

I was playing a terror mission with what looked like a basketball stadium. I shot a laser pulse-cannon from my scintar at an alien that was on one of the walls - next thing I know the game has hung.... 20-25 seconds later it's running again, but I can see that the Entire Stadium has COLLAPSED! Is this desirable? I hope there weren't any civvies in there? (There was a heavy drone - I'm hoping it's dead).
I have before/after saves if desired.

Edit - further exploring shows that the stadium is literally 2/3rds of the entire map! And all of it is collapsed.

Edited November 2, 2016 by birds_and_trees

[Charon]

I believe im correct when i quote @Chris here: " Yes, buildings are collapsable, but how they function is something even we dont know exactly anymore"

[Solver]

This is probably not a bug. Buildings in this game can collapse (there's an unfortunate delay with this though it should be 2-3 seconds on a decent computer).

Heavy drones have a pretty powerful explosion when they die. If you kill one in or next to a building then it's not too unlikely for the entire building to collapse.

[birds_and_trees]

Thanks for the responses. It was just the size of the building that collapsed that got me. That and the fact it hung my decent-ish PC for quite a while.
The drone (which was actually just a medium after all) died in the collapse, along with any remaining civvies. :-( It was the laser pule cannon that triggered it.

Edited November 2, 2016 by birds_and_trees

[Solver]

Ah yeah, the pulse cannon also does a fair bit of damage to the surroundings. And even medium drones explode. So the combination may well cause a collapse - and yes, they are fatal for everyone in the building. You can get a nasty surprise and lose soldiers this way.

I wouldn't mind taking a look at the save though if you have one before the explosion, perhaps I can see why it's so slow.

[Policenaut]

Here's my understanding of the collapsible tile system after experimenting when fixing the tropical tileset.

The collapsible tile system is pretty funky in general. Basically all tiles in the game (even indestructible tiles like dropships) situated on upper levels, that touch a tile below it with the collapsible tile setting, can come crushing down if the collapsible tile below it gets destroyed. When this happens the upper level tile deletes itself (no destruction graphic at all), the process is repeated for any tiles below as well, rubble tiles gets spawned and any units below get instantly killed (vehicles usually survive but can sometimes get killed as well).

The thing is that if the tile on the upper level (roofs etc) don't have the collapsible tile setting as well, sometimes you get situations where a single wall is holding up an entire building's roof, or in some instances all supporting walls with the collapsible tile setting on the lower level get destroyed but the roof for some reason doesn't collapse and ends up floating in the air. In other rare cases some random supporting wall on the lower level with the collapsible tile setting gets destroyed and the roof tile above collapses, which in turn makes all the other roof tiles that are connected to it collapse. This last one is probably what happened in your case.

If both the lower and upper tiles have the collapsible tile setting you don't get situations like above and units inside buildings have a greater chance to survive, since parts of the upper levels/roof collapse instead of the entire thing. However 95% of all the roof tiles in Xenonauts are indestructible and don't have the collapsible tile setting. I went through all the hundreds of roof tiles for the Xenonauts Fix Pack (the one bundled with 0.34.2 is outdated and doesn't include this fix, latest version is on steam and nexusmods) and made them destructible and gave them the collapsible tile setting. However, some larger building's roofs use the "ground tile" system (which I don't think can be set to be destructible and collapsible, but I'm not sure since there's not much info) which would require going through and editing all the possible submap buildings that use them, so I have not changed those and they might still cause these oddities. 

I hope that somewhat makes sense. Oh, and I've noticed that when those indestructible roof tiles without the collapsible tile setting are about to all collapse at the same time, is what seems to be causing the slight freezing. The fix I mentioned seems to lower the freezing when destroying buildings (but it's still somewhat there) since you get less instances of mass collapse of roof tiles.