5 files changed, 56 insertions, 5 deletions
diff --git a/src/collision.cpp b/src/collision.cpp
index a3979f1dc..16db3310c 100644
--- a/src/collision.cpp
+++ b/src/collision.cpp
@@ -189,7 +189,7 @@ static inline void getNeighborConnectingFace(v3s16 p, INodeDefManager *nodedef,
 		Map *map, MapNode n, int v, int *neighbors)
 {
 	MapNode n2 = map->getNodeNoEx(p);
-	if (nodedef->nodeboxConnects(n, n2))
+	if (nodedef->nodeboxConnects(n, n2, v))
 		*neighbors |= v;
 }
 
diff --git a/src/content_mapblock.cpp b/src/content_mapblock.cpp
index c2934f26a..6a83bd8f3 100644
--- a/src/content_mapblock.cpp
+++ b/src/content_mapblock.cpp
@@ -167,7 +167,7 @@ static inline void getNeighborConnectingFace(v3s16 p, INodeDefManager *nodedef,
 		MeshMakeData *data, MapNode n, int v, int *neighbors)
 {
 	MapNode n2 = data->m_vmanip.getNodeNoEx(p);
-	if (nodedef->nodeboxConnects(n, n2))
+	if (nodedef->nodeboxConnects(n, n2, v))
 		*neighbors |= v;
 }
 
diff --git a/src/nodedef.cpp b/src/nodedef.cpp
index 85cd848ae..edd02d9f3 100644
--- a/src/nodedef.cpp
+++ b/src/nodedef.cpp
@@ -331,6 +331,7 @@ void ContentFeatures::reset()
 	sound_dug = SimpleSoundSpec();
 	connects_to.clear();
 	connects_to_ids.clear();
+	connect_sides = 0;
 }
 
 void ContentFeatures::serialize(std::ostream &os, u16 protocol_version) const
@@ -402,6 +403,7 @@ void ContentFeatures::serialize(std::ostream &os, u16 protocol_version) const
 	for (std::set<content_t>::const_iterator i = connects_to_ids.begin();
 			i != connects_to_ids.end(); ++i)
 		writeU16(os, *i);
+	writeU8(os, connect_sides);
 }
 
 void ContentFeatures::deSerialize(std::istream &is)
@@ -479,6 +481,7 @@ void ContentFeatures::deSerialize(std::istream &is)
 	u16 connects_to_size = readU16(is);
 	for (u16 i = 0; i < connects_to_size; i++)
 		connects_to_ids.insert(readU16(is));
+	connect_sides = readU8(is);
 	}catch(SerializationError &e) {};
 }
 
@@ -517,7 +520,7 @@ public:
 	virtual void runNodeResolveCallbacks();
 	virtual void resetNodeResolveState();
 	virtual void mapNodeboxConnections();
-	virtual bool nodeboxConnects(MapNode from, MapNode to);
+	virtual bool nodeboxConnects(MapNode from, MapNode to, u8 connect_face);
 
 private:
 	void addNameIdMapping(content_t i, std::string name);
@@ -1530,7 +1533,7 @@ void CNodeDefManager::mapNodeboxConnections()
 	}
 }
 
-bool CNodeDefManager::nodeboxConnects(MapNode from, MapNode to)
+bool CNodeDefManager::nodeboxConnects(MapNode from, MapNode to, u8 connect_face)
 {
 	const ContentFeatures &f1 = get(from);
 
@@ -1547,6 +1550,24 @@ bool CNodeDefManager::nodeboxConnects(MapNode from, MapNode to)
 		// ignores actually looking if back connection exists
 		return (f2.connects_to_ids.find(from.param0) != f2.connects_to_ids.end());
 
+	// does to node declare usable faces?
+	if (f2.connect_sides > 0) {
+		if ((f2.param_type_2 == CPT2_FACEDIR) && (connect_face >= 4)) {
+			static const u8 rot[33 * 4] = {
+				0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+				4, 32, 16, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 4 - back
+				8, 4, 32, 16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 8 - right
+				0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+				16, 8, 4, 32, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 16 - front
+				0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+				0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+				0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+				32, 16, 8, 4 // 32 - left
+			};
+			return (f2.connect_sides & rot[(connect_face * 4) + to.param2]);
+		}
+		return (f2.connect_sides & connect_face);
+	}
 	// the target is just a regular node, so connect no matter back connection
 	return true;
 }
diff --git a/src/nodedef.h b/src/nodedef.h
index f92a3a941..58d0faffa 100644
--- a/src/nodedef.h
+++ b/src/nodedef.h
@@ -271,6 +271,8 @@ struct ContentFeatures
 	bool legacy_facedir_simple;
 	// Set to true if wall_mounted used to be set to true
 	bool legacy_wallmounted;
+	// for NDT_CONNECTED pairing
+	u8 connect_sides;
 
 	// Sound properties
 	SimpleSoundSpec sound_footstep;
@@ -325,7 +327,7 @@ public:
 
 	virtual void pendNodeResolve(NodeResolver *nr)=0;
 	virtual bool cancelNodeResolveCallback(NodeResolver *nr)=0;
-	virtual bool nodeboxConnects(const MapNode from, const MapNode to)=0;
+	virtual bool nodeboxConnects(const MapNode from, const MapNode to, u8 connect_face)=0;
 };
 
 class IWritableNodeDefManager : public INodeDefManager {
diff --git a/src/script/common/c_content.cpp b/src/script/common/c_content.cpp
index ababf0718..06e20c2a0 100644
--- a/src/script/common/c_content.cpp
+++ b/src/script/common/c_content.cpp
@@ -547,6 +547,34 @@ ContentFeatures read_content_features(lua_State *L, int index)
 	}
 	lua_pop(L, 1);
 
+	lua_getfield(L, index, "connect_sides");
+	if (lua_istable(L, -1)) {
+		int table = lua_gettop(L);
+		lua_pushnil(L);
+		while (lua_next(L, table) != 0) {
+			// Value at -1
+			std::string side(lua_tostring(L, -1));
+			// Note faces are flipped to make checking easier
+			if (side == "top")
+				f.connect_sides |= 2;
+			else if (side == "bottom")
+				f.connect_sides |= 1;
+			else if (side == "front")
+				f.connect_sides |= 16;
+			else if (side == "left")
+				f.connect_sides |= 32;
+			else if (side == "back")
+				f.connect_sides |= 4;
+			else if (side == "right")
+				f.connect_sides |= 8;
+			else
+				warningstream << "Unknown value for \"connect_sides\": "
+					<< side << std::endl;
+			lua_pop(L, 1);
+		}
+	}
+	lua_pop(L, 1);
+
 	lua_getfield(L, index, "selection_box");
 	if(lua_istable(L, -1))
 		f.selection_box = read_nodebox(L, -1);