Look up/down hotkeys and quality of life. (#20355)

- You can now look down open spaces by shift clicking/examining them
when they're next to you.
- You can now look up open spaces by clicking the HUD element at the top
right.
- Fixed inconsistencies with the camera getting stuck while looking up
or down. It should now be much more fluid.

---------

Co-authored-by: Matt Atlas <liermattia@gmail.com>

code/modules/multiz/movement.dm

@@ -788,38 +788,36 @@
 	simulated = FALSE
 	anchored = TRUE
 	mouse_opacity = FALSE
+	/// The mob that this observer belongs to.
 	var/mob/living/owner
-	var/tile_shifted = FALSE
+	/// The physical open-space turf we are watching.
+	var/turf/target_turf
 
-/atom/movable/z_observer/Initialize(mapload, var/mob/living/user, var/tile_shift = FALSE)
+/atom/movable/z_observer/Initialize(mapload, var/mob/living/user, var/turf/given_turf)
 	. = ..()
 	owner = user
-	if(tile_shift)
-		var/turf/T = get_step(owner, owner.dir)
-		forceMove(T)
-		tile_shifted = TRUE
+	target_turf = given_turf
 	follow()
 	RegisterSignal(owner, COMSIG_MOVABLE_MOVED, PROC_REF(follow))
 
 /atom/movable/z_observer/proc/follow()
 
 /atom/movable/z_observer/z_up/follow()
-	forceMove(get_step(owner, UP))
+	forceMove(get_step(target_turf, UP))
 	if(isturf(src.loc))
 		var/turf/T = src.loc
-		if(T && TURF_IS_MIMICING(T))
+		if((T && TURF_IS_MIMICING(T)) && (get_turf(owner) == get_step(src, DOWN)))
 			return
 	owner.reset_view(null)
 	owner.z_eye = null
 	qdel(src)
 
 /atom/movable/z_observer/z_down/follow()
-	var/turf/down_step = get_step(tile_shifted ? src : owner, DOWN)
+	var/turf/down_step = get_step(target_turf, DOWN)
 	/// If we move down more than 1 step, don't move down again.
 	if((GET_Z(owner) - down_step.z) < 2)
 		forceMove(down_step)
-	var/turf/T = get_turf(tile_shifted ? get_step(owner, owner.dir) : owner)
-	if(T && TURF_IS_MIMICING(T))
+	if(owner.Adjacent(target_turf) && (owner.dir == get_dir(owner, target_turf)))
 		return
 	owner.reset_view(null)
 	owner.z_eye = null
@@ -828,6 +826,7 @@
 /atom/movable/z_observer/Destroy()
 	UnregisterSignal(owner, COMSIG_MOVABLE_MOVED)
 	owner = null
+	target_turf = null
 	. = ..()
 
 /atom/movable/z_observer/can_fall()

code/modules/multiz/turfs/open_space.dm

@@ -209,6 +209,13 @@
 	for(var/obj/O in src)
 		O.hide(0)
 
+/turf/simulated/open/examine(mob/user, distance, is_adjacent, infix, suffix, show_extended)
+	. = ..()
+	if(isliving(user))
+		var/mob/living/looker = user
+		if(looker.Adjacent(src) && !looker.incapacitated())
+			looker.look_down_open_space(src)
+
 /turf/simulated/open/get_examine_text(mob/user, distance, is_adjacent, infix, suffix)
 	. = ..()
 	if(distance <= 2)
@@ -259,7 +266,6 @@
 	return
 
 /turf/simulated/open/attack_hand(var/mob/user)
-
 	if(ishuman(user) && user.a_intent == I_GRAB)
 		var/mob/living/carbon/human/H = user
 		var/turf/T = get_turf(H)