smashing terrain objects results in incorrect terrain underneath

[Consoleable]

Describe the bug

skylights arent seethrough due to generating wooden roof underneath

Attach save file

debug-trimmed.tar.gz

Steps to reproduce

load save file, smash skylights

Expected behavior

skylights should not generate with wooden roof underneath. They should be see through. It's okay for roofs to be underneath them, but they should not generate this way.

Screenshots

Versions and configuration

• OS: Windows
  • OS Version: 10.0.26100.6899 (24H2)
• Game Version: cdda-experimental-2025-11-07-1337-dirty [64-bit]
• Graphics Version: Tiles
• Game Language: System language []
• Mods loaded: [
  Dark Days Ahead [dda],
  Disable NPC Needs [no_npc_food],
  Portal Storms Ignore NPCs [personal_portal_storms]
  ]

Additional context

found while debugging PR related to skylights. the pr adds a flag to skylights, but this is irrrelevant to terrain genenration

[Consoleable]

when smashing floating bridges, it turns water into dirt

[PatrikLundell]

This is largely the result of how the "terrain" works. Each tile has exactly one terrain element, and there is no support for any kind of memory or other info about what the terrain should be when removed or destroyed. This means that the rather lackluster functionality of defining what should happen falls on the terrain definition itself, i.e. it can define what the result is when removed or smashed, but that is fixed. This means that if you wanted to be able to turn something to water when covering water, to air when in the air, to concrete when on top of concrete, etc. you'd have to define distinct terrain for each of these cases. That's a lot of new entries...

[Consoleable]

This is largely the result of how the "terrain" works. Each tile has exactly one terrain element, and there is no support for any kind of memory or other info about what the terrain should be when removed or destroyed. This means that the rather lackluster functionality of defining what should happen falls on the terrain definition itself, i.e. it can define what the result is when removed or smashed, but that is fixed. This means that if you wanted to be able to turn something to water when covering water, to air when in the air, to concrete when on top of concrete, etc. you'd have to define distinct terrain for each of these cases. That's a lot of new entries...

No, i'm not sure you understand, when things are being smashed, some of them are not turning into what they should be even if they have "ter_set" in "bash" properly defined.

[Consoleable]

This is largely the result of how the "terrain" works. Each tile has exactly one terrain element, and there is no support for any kind of memory or other info about what the terrain should be when removed or destroyed. This means that the rather lackluster functionality of defining what should happen falls on the terrain definition itself, i.e. it can define what the result is when removed or smashed, but that is fixed. This means that if you wanted to be able to turn something to water when covering water, to air when in the air, to concrete when on top of concrete, etc. you'd have to define distinct terrain for each of these cases. That's a lot of new entries...

the issue isnt really the entries so much as hardcoded information on regeneration in map.cpp bash functions. some of them are still making suppositions that z mode is optional/experimental and need some updates. on top of that, defining terr_set will then work, as it's busted right now for natural terrain

[Consoleable]

fixed in #83684

[Consoleable]

PLEASE NOTE:
if the terrain below a smashing floor is invalid, it will still call the terrain repair, the actual issue here is terrain repairing itself is

    ter_set( p, ter_below.roof );
} else {
    ter_set( p, ter_t_open_air );
}

causing terrain to reset EVEN IF a json has a specific ter_set indication when it's smashed. in the fix it will use ter_set unless that would result in exposing the top of a terrain that shouldn't ever be unroofed.
There are other issues that can still cause ter_set to be ignored, such as improperly exposed terrain such as in #83781