Ports large object transparency from TGMC (#21508)

Ports https://github.com/tgstation/TerraGov-Marine-Corps/pull/3528
Credit goes to original coders. This PR makes large objects transparent
when something important is behind it.

For now the list of large objects and the things make them transparent
by using this component as follows:

Large objects:

- Trees
- Cranes
- Old shipping containers (new ones doesn't allow anything to go behind
it)

The things make them transparent:
- Mobs
- Carts
- Portable generators
- Nuke

## Images


https://github.com/user-attachments/assets/a4f8ddfc-0fde-4b2d-8bd8-d15e1c6e8e0b

### Asset Licenses
The following assets that **have not** been created by myself are
included in this PR:

| Path | Original Author | License |
| --- | --- | --- |
| code/datums/components/large_object_transparency.dm | nemvar (TGMC) |
AGPLv3 |

aurorastation.dme

@@ -472,6 +472,7 @@
 #include "code\datums\components\_component.dm"
 #include "code\datums\components\connect_mob_behalf.dm"
 #include "code\datums\components\drift.dm"
+#include "code\datums\components\large_object_transparency.dm"
 #include "code\datums\components\leanable.dm"
 #include "code\datums\components\local_network.dm"
 #include "code\datums\components\orbiter.dm"

code/__DEFINES/dcs/signals.dm

@@ -15,11 +15,17 @@
 
 // /atom signals
 
+/// Called from atom/Initialize() of target: (atom/target)
+#define COMSIG_ATOM_INITIALIZED_ON "atom_initialized_on"
+
 // /area signals
 #define COMSIG_AREA_FIRE_ALARM "fire_alarm"
 
 // /turf signals
 
+/// From base of turf/ChangeTurf(): (path)
+#define COMSIG_TURF_CHANGE "turf_change"
+
 // /atom/movable signals
 
 #define COMSIG_MOVABLE_HEAR "movable_hear"

code/__DEFINES/flags.dm

@@ -66,6 +66,11 @@ GLOBAL_LIST_INIT(mimic_defines, list("ZM_MIMIC_BELOW",
 ///Shuttle transition will delete this.
 #define MOVABLE_FLAG_DEL_SHUTTLE FLAG(3)
 
+// Atom flags
+
+/// Use when this shouldn't be obscured by large icons.
+#define CRITICAL_ATOM FLAG(20)
+
 // Obj flags
 
 /// Can this object be rotated?
@@ -109,3 +114,4 @@ GLOBAL_LIST_INIT(mimic_defines, list("ZM_MIMIC_BELOW",
 #define ITEM_FLAG_NO_MOVE FLAG(12)
 /// Can be used for surgery, giving the "You're not sure what you can do with this." message if no surgery is available.
 #define ITEM_FLAG_SURGERY FLAG(13)
+

code/datums/components/large_object_transparency.dm

@@ -0,0 +1,116 @@
+///Makes large icons partially see through if high priority atoms are behind them.
+/datum/component/large_transparency
+	/// Can be positive or negative. Determines how far away from parent the first registered turf is.
+	var/x_offset
+	var/y_offset
+	/// Has to be positive or 0.
+	var/x_size
+	var/y_size
+	/// The alpha values this switches in between.
+	var/initial_alpha
+	var/target_alpha
+	/// If this is supposed to prevent clicks if it's transparent.
+	var/toggle_click
+	/// Atom's original mouse opacity, cached for restoring
+	var/initial_mouse_opacity
+	var/list/registered_turfs
+	var/amounthidden = 0
+
+/datum/component/large_transparency/Initialize(_x_offset = 0, _y_offset = 1, _x_size = 0, _y_size = 1, _initial_alpha = null, _target_alpha = 140, _toggle_click = TRUE)
+	if(!isatom(parent))
+		return COMPONENT_INCOMPATIBLE
+	x_offset = _x_offset
+	y_offset = _y_offset
+	x_size = _x_size
+	y_size = _y_size
+	var/atom/at = parent
+
+	if(isnull(_initial_alpha))
+		initial_alpha = at.alpha
+
+	else
+		initial_alpha = _initial_alpha
+	target_alpha = _target_alpha
+	toggle_click = _toggle_click
+	initial_mouse_opacity =  at.mouse_opacity
+	registered_turfs = list()
+
+
+/datum/component/large_transparency/Destroy()
+	registered_turfs.Cut()
+	return ..()
+
+/datum/component/large_transparency/RegisterWithParent()
+	RegisterSignal(parent, COMSIG_MOVABLE_MOVED, PROC_REF(OnMove))
+	RegisterWithTurfs()
+
+/datum/component/large_transparency/UnregisterFromParent()
+	UnregisterSignal(parent, COMSIG_MOVABLE_MOVED)
+	UnregisterFromTurfs()
+
+/datum/component/large_transparency/proc/RegisterWithTurfs()
+	var/turf/current_tu = get_turf(parent)
+	if(!current_tu)
+		return
+	var/turf/lowleft_tu = locate(clamp(current_tu.x + x_offset, 0, world.maxx), clamp(current_tu.y + y_offset, 0, world.maxy), current_tu.z)
+	var/turf/upright_tu = locate(min(lowleft_tu.x + x_size, world.maxx), min(lowleft_tu.y + y_size, world.maxy), current_tu.z)
+	registered_turfs = block(lowleft_tu, upright_tu) //small problems with z level edges but nothing gamebreaking.
+	//register the signals
+	for(var/regist_tu in registered_turfs)
+		if(!regist_tu)
+			continue
+		RegisterSignals(regist_tu, list(COMSIG_ATOM_ENTERED, COMSIG_ATOM_INITIALIZED_ON), PROC_REF(objectEnter))
+		RegisterSignal(regist_tu, COMSIG_ATOM_EXITED, PROC_REF(objectLeave))
+		RegisterSignal(regist_tu, COMSIG_TURF_CHANGE, PROC_REF(OnTurfChange))
+		for(var/thing in regist_tu)
+			var/atom/check_atom = thing
+			if(!(check_atom.atom_flags & CRITICAL_ATOM))
+				continue
+			amounthidden++
+	if(amounthidden)
+		reduceAlpha()
+
+/datum/component/large_transparency/proc/UnregisterFromTurfs()
+	var/list/signal_list = list(COMSIG_ATOM_ENTERED, COMSIG_ATOM_EXITED, COMSIG_TURF_CHANGE, COMSIG_ATOM_INITIALIZED_ON)
+	for(var/regist_tu in registered_turfs)
+		UnregisterSignal(regist_tu, signal_list)
+	registered_turfs.Cut()
+
+/datum/component/large_transparency/proc/OnMove()
+	SIGNAL_HANDLER
+	amounthidden = 0
+	restoreAlpha()
+	UnregisterFromTurfs()
+	RegisterWithTurfs()
+
+/datum/component/large_transparency/proc/OnTurfChange()
+	SIGNAL_HANDLER
+	addtimer(CALLBACK(src, PROC_REF(OnMove)), 1, TIMER_UNIQUE|TIMER_OVERRIDE) //*pain
+
+/datum/component/large_transparency/proc/objectEnter(datum/source, atom/enterer)
+	SIGNAL_HANDLER
+	if(!(enterer.atom_flags & CRITICAL_ATOM))
+		return
+	if(!amounthidden)
+		reduceAlpha()
+	amounthidden++
+
+/datum/component/large_transparency/proc/objectLeave(datum/source, atom/leaver, direction)
+	SIGNAL_HANDLER
+	if(!(leaver.atom_flags & CRITICAL_ATOM))
+		return
+	amounthidden = max(0, amounthidden - 1)
+	if(!amounthidden)
+		restoreAlpha()
+
+/datum/component/large_transparency/proc/reduceAlpha()
+	var/atom/par_atom = parent
+	par_atom.alpha = target_alpha
+	if(toggle_click)
+		par_atom.mouse_opacity = MOUSE_OPACITY_TRANSPARENT
+
+/datum/component/large_transparency/proc/restoreAlpha()
+	var/atom/par_atom = parent
+	par_atom.alpha = initial_alpha
+	if(toggle_click)
+		par_atom.mouse_opacity = initial_mouse_opacity

code/game/atom/atoms_initializing_EXPENSIVE.dm

@@ -129,19 +129,22 @@
 			reagents.maximum_volume += max(LAZYACCESS(reagents_to_add, v) - REAGENTS_FREE_SPACE(reagents), 0)
 			reagents.add_reagent(v, LAZYACCESS(reagents_to_add, v), LAZYACCESS(reagent_data, v))
 
-	if (light_power && light_range)
+	if(light_power && light_range)
 		update_light()
 
-	if (opacity && isturf(loc))
+	if(loc)
+		SEND_SIGNAL(loc, COMSIG_ATOM_INITIALIZED_ON, src) // used for large_object_transparency component
+
+	if(isturf(loc) && opacity)
 		var/turf/T = loc
 		T.has_opaque_atom = TRUE // No need to recalculate it in this case, it's guaranteed to be on afterwards anyways.
 
 	#ifdef AO_USE_LIGHTING_OPACITY
-		if (!mapload)
+		if(!mapload)
 			T.regenerate_ao()
 	#endif
 
-	if (update_icon_on_init)
+	if(update_icon_on_init)
 		SSicon_update.add_to_queue(src)
 
 	//Finally an aurora snowflake code that matters,

code/game/gamemodes/technomancer/instability.dm

@@ -10,6 +10,7 @@
 
 
 /mob/living
+	atom_flags = CRITICAL_ATOM
 	var/instability = 0
 	var/last_instability = 0 // Used to calculate instability delta.
 	var/last_instability_event = null // most recent world.time that something bad happened due to instability.

code/game/machinery/nuclear_bomb.dm

@@ -6,6 +6,8 @@ GLOBAL_VAR(bomb_set)
 	icon = 'icons/obj/nuke.dmi'
 	icon_state = "idle"
 	density = 1
+	atom_flags = CRITICAL_ATOM
+
 	var/deployable = 0
 	var/extended = 0
 	var/lighthack = 0

code/game/objects/structures/carts/carts.dm

@@ -8,6 +8,7 @@ ABSTRACT_TYPE(/obj/structure/cart)
 	build_amt = 15
 	material = DEFAULT_WALL_MATERIAL
 	slowdown = 0
+	atom_flags = CRITICAL_ATOM
 	var/movesound = 'sound/effects/roll.ogg'
 	var/driving
 	var/mob/living/pulling

code/game/objects/structures/coastal.dm

@@ -45,3 +45,7 @@
 	density = TRUE
 	layer = 9
 	pixel_x = -16
+
+/obj/structure/crane/Initialize()
+	. = ..()
+	AddComponent(/datum/component/large_transparency)

code/game/objects/structures/urban.dm

@@ -416,6 +416,10 @@ ABSTRACT_TYPE(/obj/structure/stairs/urban/road_ramp)
 	density = TRUE
 	layer = ABOVE_HUMAN_LAYER
 
+/obj/structure/shipping_container_old/Initialize()
+	. = ..()
+	AddComponent(/datum/component/large_transparency)
+
 /obj/effect/overlay/container_logo
 	name = "Hephaestus Industries emblem"
 	icon = 'icons/obj/structure/industrial/shipping_containers_old.dmi'

code/game/turfs/turf_changing.dm

@@ -60,6 +60,7 @@
 	var/old_is_open = is_open()
 	var/list/old_resources = resources ? resources.Copy() : null
 
+	SEND_SIGNAL(src, COMSIG_TURF_CHANGE, path)
 	changing_turf = TRUE
 
 	if(connections)

code/modules/overmap/exoplanets/decor/flora/_tree.dm

@@ -13,6 +13,10 @@
 	var/stumptype = /obj/structure/flora/stump //stump to make when chopped
 	var/static/list/fall_forbid = list(/obj/structure/flora, /obj/effect, /obj/structure/bonfire, /obj/structure/pit)
 
+/obj/structure/flora/tree/Initialize()
+	. = ..()
+	AddComponent(/datum/component/large_transparency)
+
 /obj/structure/flora/tree/proc/update_desc()
 	desc = initial(desc)
 	switch(chop_health / max_chop_health)

code/modules/power/portgen.dm

@@ -7,6 +7,7 @@
 	var/base_icon = "portgen0"
 	density = TRUE
 	anchored = FALSE
+	atom_flags = CRITICAL_ATOM
 
 	var/active = FALSE
 	var/power_gen = 5000

html/changelogs/kano-dot-let_me_make_myself_very_clear_gif.yml

@@ -0,0 +1,7 @@
+
+author: Kano
+
+delete-after: True
+
+changes:
+  - qol: "Ported large object transparency from TGMC, allowing to see some things hiding behind large icons."