[MIRROR] Disease and blob camera mobs can move vertically while a location or host hasn't been chosen yet. Revenants can also freely move vertically. [MDB IGNORE] (#11315)

* Disease and blob camera mobs can move vertically while a location or host hasn't been chosen yet. Revenants can also freely move vertically. (#64626)

I found out on the icebox map, roughly a week or two ago, that the camera mob couldn't be moved to the other station leveleven before the core was placed. I believe this to be an oversight, which is why this PR has been made.
Sentient diseases also suffer from a similar issue while on the host selection stage, so I'm fixing that too.

EDIT: Someone pointed out that revenants (and other mobs with incorporeal movement) don't ignore turfs and obstacles when moving vertically, so I have added a few lines to living/can_z_move to hopefully fix that.

* Disease and blob camera mobs can move vertically while a location or host hasn't been chosen yet. Revenants can also freely move vertically.

Co-authored-by: Ghom <42542238+Ghommie@users.noreply.github.com>

code/modules/antagonists/blob/overmind.dm

@@ -107,7 +107,16 @@ GLOBAL_LIST_EMPTY(blob_nodes)
 				to_chat(src, "The <b><font color=\"[blobstrain.color]\">[blobstrain.name]</b></font> strain [blobstrain.effectdesc]")
 
 /mob/camera/blob/can_z_move(direction, turf/start, turf/destination, z_move_flags = NONE, mob/living/rider)
-	return FALSE
+	if(placed) // The blob can't expand vertically (yet)
+		return FALSE
+	. = ..()
+	if(!.)
+		return
+	var/turf/target_turf = .
+	if(!is_valid_turf(target_turf)) // Allows unplaced blobs to travel through station z-levels
+		if(z_move_flags & ZMOVE_FEEDBACK)
+			to_chat(src, "Your destination is invalid. Move somewhere else and try again.")
+		return null
 
 /mob/camera/blob/proc/is_valid_turf(turf/T)
 	var/area/A = get_area(T)

code/modules/antagonists/blob/powers.dm

@@ -28,8 +28,7 @@
 		if(T.density)
 			to_chat(src, span_warning("This spot is too dense to place a blob core on!"))
 			return FALSE
-		var/area/A = get_area(T)
-		if(isspaceturf(T) || A && !(A.area_flags & BLOBS_ALLOWED))
+		if(!is_valid_turf(T))
 			to_chat(src, span_warning("You cannot place your core here!"))
 			return FALSE
 		for(var/obj/O in T)

code/modules/antagonists/disease/disease_mob.dm

@@ -135,6 +135,8 @@ the new instance inside the host to be updated to the template's stats.
 			last_move_tick = world.time
 
 /mob/camera/disease/can_z_move(direction, turf/start, turf/destination, z_move_flags = NONE, mob/living/rider)
+	if(freemove)
+		return ..()
 	return FALSE
 
 /mob/camera/disease/Hear(message, atom/movable/speaker, message_language, raw_message, radio_freq, list/spans, list/message_mods = list())

code/modules/mob/camera/camera.dm

@@ -21,5 +21,23 @@
 /mob/camera/canUseStorage()
 	return FALSE
 
+/mob/camera/up()
+	set name = "Move Upwards"
+	set category = "IC"
+
+	if(zMove(UP, z_move_flags = ZMOVE_FEEDBACK))
+		to_chat(src, span_notice("You move upwards."))
+
+/mob/camera/down()
+	set name = "Move Down"
+	set category = "IC"
+
+	if(zMove(DOWN, z_move_flags = ZMOVE_FEEDBACK))
+		to_chat(src, span_notice("You move down."))
+
+/mob/camera/can_z_move(direction, turf/start, turf/destination, z_move_flags = NONE, mob/living/rider)
+	z_move_flags |= ZMOVE_IGNORE_OBSTACLES  //cameras do not respect these FLOORS you speak so much of
+	return ..()
+
 /mob/camera/emote(act, m_type=1, message = null, intentional = FALSE, force_silence = FALSE)
 	return FALSE

code/modules/mob/living/living_movement.dm

@@ -83,6 +83,11 @@
 			to_chat(rider || src, span_warning("[rider ? src : "You"] can't do that right now!"))
 		return FALSE
 	if(!buckled || !(z_move_flags & ZMOVE_ALLOW_BUCKLED))
+		if(!(z_move_flags & ZMOVE_FALL_CHECKS) && incorporeal_move && (!rider || rider.incorporeal_move))
+			//An incorporeal mob will ignore obstacles unless it's a potential fall (it'd suck hard) or is carrying corporeal mobs.
+			//Coupled with flying/floating, this allows the mob to move up and down freely.
+			//By itself, it only allows the mob to move down.
+			z_move_flags |= ZMOVE_IGNORE_OBSTACLES
 		return ..()
 	switch(SEND_SIGNAL(buckled, COMSIG_BUCKLED_CAN_Z_MOVE, direction, start, destination, z_move_flags, src))
 		if(COMPONENT_RIDDEN_ALLOW_Z_MOVE) // Can be ridden.

code/modules/mob/living/silicon/ai/freelook/eye.dm

@@ -106,10 +106,6 @@
 	if(.)
 		setLoc(loc, force_update = TRUE)
 
-/mob/camera/ai_eye/can_z_move(direction, turf/start, turf/destination, z_move_flags = NONE, mob/living/rider)
-	z_move_flags |= ZMOVE_IGNORE_OBSTACLES  //cameras do not respect these FLOORS you speak so much of
-	return ..()
-
 /mob/camera/ai_eye/Move()
 	return