Refactors how diagonal smoothing underlays work (#1187)

code/game/turfs/simulated/floor/fancy_floor.dm

@@ -140,7 +140,7 @@
 	floor_tile = /obj/item/stack/tile/carpet
 	broken_states = list("damaged")
 	smooth = SMOOTH_TRUE
-	canSmoothWith = list(/turf/open/floor/carpet, /turf/open/chasm)
+	canSmoothWith = list(/turf/open/floor/carpet)
 	flags = NONE
 
 /turf/open/floor/carpet/Initialize()
@@ -175,15 +175,22 @@
 	burnt = 1
 	update_icon()
 
+/turf/open/floor/carpet/get_smooth_underlay_icon(mutable_appearance/underlay_appearance, turf/asking_turf, adjacency_dir)
+	return FALSE
 
 
-turf/open/floor/fakepit
+/turf/open/floor/fakepit
 	desc = "A clever illusion designed to look like a bottomless pit."
 	smooth = SMOOTH_TRUE | SMOOTH_BORDER | SMOOTH_MORE
-	canSmoothWith = list(/turf/open/floor/fakepit, /turf/open/chasm)
+	canSmoothWith = list(/turf/open/floor/fakepit)
 	icon = 'icons/turf/floors/Chasms.dmi'
 	icon_state = "smooth"
 
+/turf/open/floor/fakepit/get_smooth_underlay_icon(mutable_appearance/underlay_appearance, turf/asking_turf, adjacency_dir)
+	underlay_appearance.icon = 'icons/turf/floors.dmi'
+	underlay_appearance.icon_state = "basalt"
+	return TRUE
+
 /turf/open/floor/fakespace
 	icon = 'icons/turf/space.dmi'
 	icon_state = "0"
@@ -193,4 +200,10 @@ turf/open/floor/fakepit
 
 /turf/open/floor/fakespace/Initialize()
 	..()
-	icon_state = "[rand(0,25)]"
+	icon_state = SPACE_ICON_STATE
+
+/turf/open/floor/fakespace/get_smooth_underlay_icon(mutable_appearance/underlay_appearance, turf/asking_turf, adjacency_dir)
+	underlay_appearance.icon = 'icons/turf/space.dmi'
+	underlay_appearance.icon_state = SPACE_ICON_STATE
+	underlay_appearance.plane = PLANE_SPACE
+	return TRUE

code/game/turfs/simulated/floor/plating/lava.dm

@@ -38,6 +38,11 @@
 /turf/open/floor/plating/lava/make_plating()
 	return
 
+/turf/open/floor/plating/lava/get_smooth_underlay_icon(mutable_appearance/underlay_appearance, turf/asking_turf, adjacency_dir)
+	underlay_appearance.icon = 'icons/turf/floors.dmi'
+	underlay_appearance.icon_state = "basalt"
+	return TRUE
+
 /turf/open/floor/plating/lava/GetHeatCapacity()
 	. = 700000