[NO GBP] Fixes the larva "hide" ability not properly hiding larvas under tables. (#81921)

## About The Pull Request
This PR fixes yet another small issue with elevation.

## Why It's Good For The Game
This PR fixes yet another small issue with elevation.

## Changelog

🆑
fix: Fixed the larva "hide" ability not properly hiding larvas under
tables.
/🆑

code/__DEFINES/traits/declarations.dm

@@ -509,6 +509,8 @@ Remember to update _globalvars/traits.dm if you're adding/removing/renaming trai
 
 /// 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"
+/// Does the mob ignore elevation? (e.g. xeno larvas on hiding)
+#define TRAIT_IGNORE_ELEVATION "ignore_elevation"
 
 /// Prevents you from twohanding weapons.
 #define TRAIT_NO_TWOHANDING "no_twohanding"

code/_globalvars/traits/_traits.dm

@@ -255,6 +255,7 @@ GLOBAL_LIST_INIT(traits_by_type, list(
 		"TRAIT_HULK" = TRAIT_HULK,
 		"TRAIT_HUSK" = TRAIT_HUSK,
 		"TRAIT_ID_APPRAISER" = TRAIT_ID_APPRAISER,
+		"TRAIT_IGNORE_ELEVATION" = TRAIT_IGNORE_ELEVATION,
 		"TRAIT_IGNOREDAMAGESLOWDOWN" = TRAIT_IGNOREDAMAGESLOWDOWN,
 		"TRAIT_IGNORESLOWDOWN" = TRAIT_IGNORESLOWDOWN,
 		"TRAIT_IGNORING_GRAVITY" = TRAIT_IGNORING_GRAVITY,

code/_globalvars/traits/admin_tooling.dm

@@ -96,6 +96,7 @@ GLOBAL_LIST_INIT(admin_visible_traits, list(
 		"TRAIT_HIDE_EXTERNAL_ORGANS" = TRAIT_HIDE_EXTERNAL_ORGANS,
 		"TRAIT_HOLY" = TRAIT_HOLY,
 		"TRAIT_HUSK" = TRAIT_HUSK,
+		"TRAIT_IGNORE_ELEVATION" = TRAIT_IGNORE_ELEVATION,
 		"TRAIT_IGNOREDAMAGESLOWDOWN" = TRAIT_IGNOREDAMAGESLOWDOWN,
 		"TRAIT_IGNORESLOWDOWN" = TRAIT_IGNORESLOWDOWN,
 		"TRAIT_ILLITERATE" = TRAIT_ILLITERATE,

code/datums/elements/elevation.dm

@@ -113,6 +113,8 @@
 	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))
+		RegisterSignal(living, SIGNAL_ADDTRAIT(TRAIT_IGNORE_ELEVATION), PROC_REF(on_ignore_elevation_add))
+		RegisterSignal(living, SIGNAL_REMOVETRAIT(TRAIT_IGNORE_ELEVATION), PROC_REF(on_ignore_elevation_remove))
 		elevate_mob(living)
 
 /datum/element/elevation_core/Detach(datum/source)
@@ -133,7 +135,7 @@
 			continue
 		REMOVE_TRAIT(living, TRAIT_ON_ELEVATED_SURFACE, REF(src))
 		elevate_mob(living, -pixel_shift)
-		UnregisterSignal(living, COMSIG_LIVING_SET_BUCKLED)
+		UnregisterSignal(living, list(COMSIG_LIVING_SET_BUCKLED, SIGNAL_ADDTRAIT(TRAIT_IGNORE_ELEVATION), SIGNAL_REMOVETRAIT(TRAIT_IGNORE_ELEVATION)))
 	return ..()
 
 /datum/element/elevation_core/proc/on_entered(turf/source, atom/movable/entered, atom/old_loc)
@@ -143,6 +145,8 @@
 		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))
+		RegisterSignal(entered, SIGNAL_ADDTRAIT(TRAIT_IGNORE_ELEVATION), PROC_REF(on_ignore_elevation_add))
+		RegisterSignal(entered, SIGNAL_REMOVETRAIT(TRAIT_IGNORE_ELEVATION), PROC_REF(on_ignore_elevation_remove))
 
 /datum/element/elevation_core/proc/on_initialized_on(turf/source, atom/movable/spawned)
 	SIGNAL_HANDLER
@@ -152,15 +156,17 @@
 /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))
-		// Always unregister the signal, we're still leaving even if already shifted down.
-		UnregisterSignal(gone, COMSIG_LIVING_SET_BUCKLED)
+		// Always unregister the signals, we're still leaving even if not affected by elevation.
+		UnregisterSignal(gone, list(COMSIG_LIVING_SET_BUCKLED, SIGNAL_ADDTRAIT(TRAIT_IGNORE_ELEVATION), SIGNAL_REMOVETRAIT(TRAIT_IGNORE_ELEVATION)))
 		if(!HAS_TRAIT_FROM(gone, TRAIT_ON_ELEVATED_SURFACE, REF(src)))
 			return
 		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)
 
-/datum/element/elevation_core/proc/elevate_mob(mob/living/target, z_shift = pixel_shift, elevate_time = ELEVATE_TIME)
+/datum/element/elevation_core/proc/elevate_mob(mob/living/target, z_shift = pixel_shift, elevate_time = ELEVATE_TIME, force = FALSE)
+	if(HAS_TRAIT(target, TRAIT_IGNORE_ELEVATION) && !force)
+		return
 	var/buckled_to_vehicle = FALSE
 	if(target.buckled)
 		if(isvehicle(target.buckled))
@@ -181,6 +187,8 @@
  */
 /datum/element/elevation_core/proc/on_set_buckled(mob/living/source, atom/movable/new_buckled)
 	SIGNAL_HANDLER
+	if(HAS_TRAIT(source, TRAIT_IGNORE_ELEVATION))
+		return
 	if(source.buckled)
 		if(isvehicle(source.buckled))
 			animate(source.buckled, pixel_z = -pixel_shift, time = ELEVATE_TIME, flags = ANIMATION_RELATIVE|ANIMATION_PARALLEL)
@@ -193,6 +201,14 @@
 	else if(!isliving(new_buckled))
 		animate(source, pixel_z = -pixel_shift, time = ELEVATE_TIME, flags = ANIMATION_RELATIVE|ANIMATION_PARALLEL)
 
+/datum/element/elevation_core/proc/on_ignore_elevation_add(mob/living/source, trait)
+	SIGNAL_HANDLER
+	elevate_mob(source, -pixel_shift, force = TRUE)
+
+/datum/element/elevation_core/proc/on_ignore_elevation_remove(mob/living/source, trait)
+	SIGNAL_HANDLER
+	elevate_mob(source, pixel_shift)
+
 /datum/element/elevation_core/proc/on_reset_elevation(turf/source, list/current_values)
 	SIGNAL_HANDLER
 	current_values[ELEVATION_CURRENT_PIXEL_SHIFT] = pixel_shift

code/modules/mob/living/carbon/alien/larva/powers.dm

@@ -13,6 +13,7 @@
 			span_notice("[owner] slowly peeks up from the ground..."),
 			span_noticealien("You stop hiding."),
 		)
+		ADD_TRAIT(owner, TRAIT_IGNORE_ELEVATION, ACTION_TRAIT)
 
 	else
 		owner.layer = hide_layer
@@ -20,6 +21,7 @@
 			span_name("[owner] scurries to the ground!"),
 			span_noticealien("You are now hiding."),
 		)
+		REMOVE_TRAIT(owner, TRAIT_IGNORE_ELEVATION, ACTION_TRAIT)
 
 	return TRUE