Properly remove SAO when worldedges are overtaken (#5889)

* LuaEntitySAO: Remove beyond outermost mapchunk edges

Based on a commit by, and with help from, nerzhul.
Add 2 functions to class Mapgen:
A function to calculate actual mapgen edges, called from the Mapgen constructor.
A function called indirectly from content_sao.cpp per entity step to check SAO
position is within mapgen edges.

* Calculate borders from params not mapgen, which is not available everytime

5 files changed, 84 insertions, 8 deletions

diff --git a/src/content_sao.cpp b/src/content_sao.cpp
index f435fe938..be1c52fe6 100644
--- a/src/content_sao.cpp
+++ b/src/content_sao.cpp
@@ -406,6 +406,20 @@ void LuaEntitySAO::step(float dtime, bool send_recommended)
 		m_env->getScriptIface()->luaentity_Step(m_id, dtime);
 	}
 
+	// Remove LuaEntity beyond terrain edges
+	{
+		ServerMap *map = dynamic_cast<ServerMap *>(&m_env->getMap());
+		assert(map);
+		if (!m_pending_deactivation &&
+				map->saoPositionOverLimit(m_base_position)) {
+			infostream << "Remove SAO " << m_id << "(" << m_init_name
+				<< "), outside of limits" << std::endl;
+			m_pending_deactivation = true;
+			m_removed = true;
+			return;
+		}
+	}
+
 	if(send_recommended == false)
 		return;
 
diff --git a/src/map.cpp b/src/map.cpp
index 641b7d2dd..3b02ac02f 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -1378,6 +1378,11 @@ s16 ServerMap::getWaterLevel()
 	return getMapgenParams()->water_level;
 }
 
+bool ServerMap::saoPositionOverLimit(const v3f &p)
+{
+	return getMapgenParams()->saoPosOverLimit(p);
+}
+
 bool ServerMap::blockpos_over_mapgen_limit(v3s16 p)
 {
 	const s16 mapgen_limit_bp = rangelim(
@@ -1838,9 +1843,6 @@ MapBlock *ServerMap::getBlockOrEmerge(v3s16 p3d)
 	return block;
 }
 
-void ServerMap::prepareBlock(MapBlock *block) {
-}
-
 // N.B.  This requires no synchronization, since data will not be modified unless
 // the VoxelManipulator being updated belongs to the same thread.
 void ServerMap::updateVManip(v3s16 pos)
diff --git a/src/map.h b/src/map.h
index 41a1a246b..4b6e08f96 100644
--- a/src/map.h
+++ b/src/map.h
@@ -377,6 +377,8 @@ public:
 	*/
 	ServerMapSector *createSector(v2s16 p);
 
+	bool saoPositionOverLimit(const v3f &p);
+
 	/*
 		Blocks are generated by using these and makeBlock().
 	*/
@@ -409,9 +411,6 @@ public:
 	*/
 	MapBlock *getBlockOrEmerge(v3s16 p3d);
 
-	// Carries out any initialization necessary before block is sent
-	void prepareBlock(MapBlock *block);
-
 	// Helper for placing objects on ground level
 	s16 findGroundLevel(v2s16 p2d);
 
diff --git a/src/mapgen.cpp b/src/mapgen.cpp
index dfe413a71..1f7f98621 100644
--- a/src/mapgen.cpp
+++ b/src/mapgen.cpp
@@ -317,7 +317,6 @@ void Mapgen::updateHeightmap(v3s16 nmin, v3s16 nmax)
 			heightmap[index] = y;
 		}
 	}
-	//printf("updateHeightmap: %dus\n", t.stop());
 }
 
 inline bool Mapgen::isLiquidHorizontallyFlowable(u32 vi, v3s16 em)
@@ -1049,3 +1048,54 @@ void MapgenParams::writeParams(Settings *settings) const
 	if (bparams)
 		bparams->writeParams(settings);
 }
+
+// Calculate edges of outermost generated mapchunks (less than
+// 'mapgen_limit'), and corresponding exact limits for SAO entities.
+void MapgenParams::calcMapgenEdges()
+{
+	// Central chunk offset, in blocks
+	s16 ccoff_b = -chunksize / 2;
+
+	// Chunksize, in nodes
+	s32 csize_n = chunksize * MAP_BLOCKSIZE;
+
+	// Minp/maxp of central chunk, in nodes
+	s16 ccmin = ccoff_b * MAP_BLOCKSIZE;
+	s16 ccmax = ccmin + csize_n - 1;
+	// Fullminp/fullmaxp of central chunk, in nodes
+	s16 ccfmin = ccmin - MAP_BLOCKSIZE;
+	s16 ccfmax = ccmax + MAP_BLOCKSIZE;
+	// Effective mapgen limit, in blocks
+	// Uses same calculation as ServerMap::blockpos_over_mapgen_limit(v3s16 p)
+	s16 mapgen_limit_b = rangelim(mapgen_limit,
+		0, MAX_MAP_GENERATION_LIMIT) / MAP_BLOCKSIZE;
+	// Effective mapgen limits, in nodes
+	s16 mapgen_limit_min = -mapgen_limit_b * MAP_BLOCKSIZE;
+	s16 mapgen_limit_max = (mapgen_limit_b + 1) * MAP_BLOCKSIZE - 1;
+	// Number of complete chunks from central chunk fullminp/fullmaxp
+	// to effective mapgen limits.
+	s16 numcmin = MYMAX((ccfmin - mapgen_limit_min) / csize_n, 0);
+	s16 numcmax = MYMAX((mapgen_limit_max - ccfmax) / csize_n, 0);
+	// Mapgen edges, in nodes
+	// These values may be useful later as additional class members
+	s16 mapgen_edge_min = ccmin - numcmin * csize_n;
+	s16 mapgen_edge_max = ccmax + numcmax * csize_n;
+	// SAO position limits, in Irrlicht units
+	m_sao_limit_min = mapgen_edge_min * BS - 3.0f;
+	m_sao_limit_max = mapgen_edge_max * BS + 3.0f;
+}
+
+
+bool MapgenParams::saoPosOverLimit(const v3f &p)
+{
+	if (!m_sao_limit_calculated) {
+		calcMapgenEdges();
+		m_sao_limit_calculated = true;
+	}
+	return p.X < m_sao_limit_min ||
+		p.X > m_sao_limit_max ||
+		p.Y < m_sao_limit_min ||
+		p.Y > m_sao_limit_max ||
+		p.Z < m_sao_limit_min ||
+		p.Z > m_sao_limit_max;
+}
diff --git a/src/mapgen.h b/src/mapgen.h
index 1efd2bff7..222838011 100644
--- a/src/mapgen.h
+++ b/src/mapgen.h
@@ -138,7 +138,10 @@ struct MapgenParams {
 		water_level(1),
 		mapgen_limit(MAX_MAP_GENERATION_LIMIT),
 		flags(MG_CAVES | MG_LIGHT | MG_DECORATIONS),
-		bparams(NULL)
+		bparams(NULL),
+		m_sao_limit_min(MAX_MAP_GENERATION_LIMIT * BS),
+		m_sao_limit_max(MAX_MAP_GENERATION_LIMIT * BS),
+		m_sao_limit_calculated(false)
 	{
 	}
 
@@ -146,6 +149,14 @@ struct MapgenParams {
 
 	virtual void readParams(const Settings *settings);
 	virtual void writeParams(Settings *settings) const;
+
+	bool saoPosOverLimit(const v3f &p);
+private:
+	void calcMapgenEdges();
+
+	float m_sao_limit_min;
+	float m_sao_limit_max;
+	bool m_sao_limit_calculated;
 };