Z-Mimic: Synchronize with upstream

code/__defines/zmimic.dm

@@ -1,7 +1,28 @@
+#define ZM_DESTRUCTION_TIMER(TARGET) addtimer(CALLBACK(TARGET, /datum/.proc/qdel_self), 10 SECONDS, TIMER_STOPPABLE)
 #define TURF_IS_MIMICKING(T) (isturf(T) && (T:z_flags & ZM_MIMIC_BELOW))
-#define CHECK_OO_EXISTENCE(OO) if (OO && !TURF_IS_MIMICKING(OO.loc)) { qdel(OO); }
+#define CHECK_OO_EXISTENCE(OO) if (OO && !MOVABLE_IS_ON_ZTURF(OO) && !OO.destruction_timer) { OO.destruction_timer = ZM_DESTRUCTION_TIMER(OO); }
 #define UPDATE_OO_IF_PRESENT CHECK_OO_EXISTENCE(bound_overlay); if (bound_overlay) { update_above(); }
 
+// I do not apologize.
+
+// These aren't intended to be used anywhere else, they just can't be undef'd because DM is dum.
+#define ZM_INTERNAL_SCAN_LOOKAHEAD(M,VTR,F) ((get_step(M, M:dir)?:VTR & F) || (get_step(M, turn(M:dir, 180))?:VTR & F))
+#define ZM_INTERNAL_SCAN_LOOKBESIDE(M,VTR,F) ((get_step(M, turn(M:dir, 90))?:VTR & F) || (get_step(M, turn(M:dir, -90))?:VTR & F))
+
+/// Is this movable visible from a turf that is mimicking below? Note: this does not necessarily mean *directly* below.
+#define MOVABLE_IS_BELOW_ZTURF(M) (\
+	isturf(M:loc) && (TURF_IS_MIMICKING(M:loc:above) \
+	|| ((M:z_flags & ZMM_LOOKAHEAD) && ZM_INTERNAL_SCAN_LOOKAHEAD(M, above?:z_flags, ZM_MIMIC_BELOW))  \
+	|| ((M:z_flags & ZMM_LOOKBESIDE) && ZM_INTERNAL_SCAN_LOOKBESIDE(M, above?:z_flags, ZM_MIMIC_BELOW))) \
+)
+/// Is this movable located on a turf that is mimicking below? Note: this does not necessarily mean *directly* on.
+#define MOVABLE_IS_ON_ZTURF(M) (\
+	isturf(M:loc) && (TURF_IS_MIMICKING(M:loc:above) \
+	|| ((M:z_flags & ZMM_LOOKAHEAD) && ZM_INTERNAL_SCAN_LOOKAHEAD(M, z_flags, ZM_MIMIC_BELOW)) \
+	|| ((M:z_flags & ZMM_LOOKBESIDE) && ZM_INTERNAL_SCAN_LOOKBESIDE(M, z_flags, ZM_MIMIC_BELOW))) \
+)
+#define MOVABLE_SHALL_MIMIC(AM) (!(AM.z_flags & ZMM_IGNORE) && MOVABLE_IS_BELOW_ZTURF(AM))
+
 // Turf MZ flags.
 #define ZM_MIMIC_BELOW     1	//! If this turf should mimic the turf on the Z below.
 #define ZM_MIMIC_OVERWRITE 2	//! If this turf is Z-mimicking, overwrite the turf's appearance instead of using a movable. This is faster, but means the turf cannot have its own appearance (say, edges or a translucent sprite).
@@ -26,5 +47,7 @@ var/global/list/mimic_defines = list(
 )
 
 // Movable flags.
-#define ZMM_IGNORE 1	//! Do not copy this movable.
-#define ZMM_MANGLE_PLANES  2	//! Check this movable's overlays/underlays for explicit plane use and mangle for compatibility with Z-Mimic. If you're using emissive overlays, you probably should be using this flag. Expensive, only use if necessary.
+#define ZMM_IGNORE        1	//! Do not copy this movable.
+#define ZMM_MANGLE_PLANES 2	//! Check this movable's overlays/underlays for explicit plane use and mangle for compatibility with Z-Mimic. If you're using emissive overlays, you probably should be using this flag. Expensive, only use if necessary.
+#define ZMM_LOOKAHEAD     3	//! Look one turf ahead and one turf back when considering z-turfs that might be seeing this atom. Cheap, but not free.
+#define ZMM_LOOKBESIDE    4	//! Look one turf beside (left/right) when considering z-turfs that might be seeing this atom. Cheap, but not free.