[MIRROR] Prevents something fucky with elevation and glass tables [MD…

…B IGNORE] (#25567)

* Prevents something fucky with elevation and glass tables (#80187)

## About The Pull Request
Objects can be destroyed during a movement loop before the abstract
entered signal can be sent, so we need to make sure only mobs that have
been elevated are dropped down.

## Why It's Good For The Game
Fixes #80169

## Changelog

:cl:
fix: climbing or being shoved into a glass table won't cause elevation
issues.
/:cl:

---------

Co-authored-by: san7890 <the@ san7890.com>

* Prevents something fucky with elevation and glass tables

---------

Co-authored-by: Ghom <[email protected]>
Co-authored-by: san7890 <the@ san7890.com>

code/__DEFINES/traits/declarations.dm

@@ -484,6 +484,9 @@ Remember to update _globalvars/traits.dm if you're adding/removing/renaming trai
 /// Whether or not the user is in a MODlink call, prevents making more calls
 #define TRAIT_IN_CALL "in_call"
 
+/// Is the mob standing on an elevated surface? This prevents them from dropping down if not elevated first.
+#define TRAIT_ON_ELEVATED_SURFACE "on_elevated_surface"
+
 // METABOLISMS
 // Various jobs on the station have historically had better reactions
 // to various drinks and foodstuffs. Security liking donuts is a classic

code/_globalvars/traits/_traits.dm

@@ -327,6 +327,7 @@ GLOBAL_LIST_INIT(traits_by_type, list(
 		"TRAIT_NOSOFTCRIT" = TRAIT_NOSOFTCRIT,
 		"TRAIT_NUKEIMMUNE" = TRAIT_NUKEIMMUNE,
 		"TRAIT_OIL_FRIED" = TRAIT_OIL_FRIED,
+		"TRAIT_ON_ELEVATED_SURFACE" = TRAIT_ON_ELEVATED_SURFACE,
 		"TRAIT_ORBITING_FORBIDDEN" = TRAIT_ORBITING_FORBIDDEN,
 		"TRAIT_OVERDOSEIMMUNE" = TRAIT_OVERDOSEIMMUNE,
 		"TRAIT_OVERWATCH_IMMUNE" = TRAIT_OVERWATCH_IMMUNE,

code/datums/elements/elevation.dm

@@ -110,6 +110,7 @@
 	ADD_TRAIT(target, TRAIT_ELEVATED_TURF, REF(src))
 
 	for(var/mob/living/living in target)
+		ADD_TRAIT(living, TRAIT_ON_ELEVATED_SURFACE, REF(src))
 		RegisterSignal(living, COMSIG_LIVING_SET_BUCKLED, PROC_REF(on_set_buckled))
 		elevate_mob(living)
 
@@ -127,13 +128,17 @@
 	))
 	REMOVE_TRAIT(source, TRAIT_ELEVATED_TURF, REF(src))
 	for(var/mob/living/living in source)
+		if(!HAS_TRAIT_FROM(living, TRAIT_ON_ELEVATED_SURFACE, REF(src)))
+			continue
+		REMOVE_TRAIT(living, TRAIT_ON_ELEVATED_SURFACE, REF(src))
 		elevate_mob(living, -pixel_shift)
 		UnregisterSignal(living, COMSIG_LIVING_SET_BUCKLED)
 	return ..()
 
 /datum/element/elevation_core/proc/on_entered(turf/source, atom/movable/entered, atom/old_loc)
 	SIGNAL_HANDLER
 	if((isnull(old_loc) || !HAS_TRAIT_FROM(old_loc, TRAIT_ELEVATED_TURF, REF(src))) && isliving(entered))
+		ADD_TRAIT(entered, TRAIT_ON_ELEVATED_SURFACE, REF(src))
 		var/elevate_time = isturf(old_loc) && source.Adjacent(old_loc) ? ELEVATE_TIME : 0
 		elevate_mob(entered, elevate_time = elevate_time)
 		RegisterSignal(entered, COMSIG_LIVING_SET_BUCKLED, PROC_REF(on_set_buckled))
@@ -146,6 +151,7 @@
 /datum/element/elevation_core/proc/on_exited(turf/source, atom/movable/gone)
 	SIGNAL_HANDLER
 	if((isnull(gone.loc) || !HAS_TRAIT_FROM(gone.loc, TRAIT_ELEVATED_TURF, REF(src))) && isliving(gone))
+		REMOVE_TRAIT(gone, TRAIT_ON_ELEVATED_SURFACE, REF(src))
 		var/elevate_time = isturf(gone.loc) && source.Adjacent(gone.loc) ? ELEVATE_TIME : 0
 		elevate_mob(gone, -pixel_shift, elevate_time)
 		UnregisterSignal(gone, COMSIG_LIVING_SET_BUCKLED)