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

1 files changed, 51 insertions, 1 deletions

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;
+}