Implement slime chunks. (#5484)

* Implement slime chunks.

* add cWorld::IsSlimeChunk

* add documentation for cWorld::IsSlimeChunk

Server/Plugins/APIDump/Classes/World.lua

@@ -2315,6 +2315,27 @@ function OnAllChunksAvailable()</pre> All return values from the callbacks are i
 				},
 				Notes = "Returns whether or not saving chunk data is enabled. If disabled, the world will keep dirty chunks in memory forever, and will simply regenerate non-dirty chunks that are unloaded.",
 			},
+			IsSlimeChunk =
+			{
+				Params =
+				{
+					{
+						Name = "ChunkX",
+						Type = "number",
+					},
+					{
+						Name = "ChunkZ",
+						Type = "number",
+					},
+				},
+				Returns =
+				{
+					{
+						Type = "boolean",
+					},
+				},
+				Notes = "Returns whether slimes can spawn in the chunk.",
+			},
 			IsTrapdoorOpen =
 			{
 				Params =

src/Chunk.cpp

@@ -1980,3 +1980,12 @@ NIBBLETYPE cChunk::GetTimeAlteredLight(NIBBLETYPE a_Skylight) const
 	// Because NIBBLETYPE is unsigned, we clamp it to 0 .. 15 by checking for values above 15
 	return (a_Skylight < 16)? a_Skylight : 0;
 }
+
+
+
+
+
+bool cChunk::IsSlimeChunk() const
+{
+	return m_World->IsSlimeChunk(m_PosX, m_PosZ);
+}

src/Chunk.h

@@ -452,6 +452,8 @@ public:
 		return cChunkDef::RelativeToAbsolute(a_RelBlockPosition, {m_PosX, m_PosZ});
 	}
 
+	/** Returns true if slimes should spawn in the chunk. */
+	bool IsSlimeChunk() const;
 
 private:
 

src/MobSpawner.cpp

@@ -220,7 +220,10 @@ bool cMobSpawner::CanSpawnHere(cChunk * a_Chunk, Vector3i a_RelPos, eMonsterType
 					(!cBlockInfo::IsTransparent(BlockBelow)) ||
 					(a_DisableSolidBelowCheck)) &&
 				(
-					(a_RelPos.y <= 40) ||
+					(
+						(a_RelPos.y <= 40) &&
+						a_Chunk->IsSlimeChunk()
+					) ||
 					(
 						(a_Biome == biSwampland) &&
 						(a_RelPos.y >= 50) &&

src/World.cpp

@@ -3229,3 +3229,13 @@ void cWorld::cChunkGeneratorCallbacks::CallHookChunkGenerated (cChunkDesc & a_Ch
 		*m_World, a_ChunkDesc.GetChunkX(), a_ChunkDesc.GetChunkZ(), &a_ChunkDesc
 	);
 }
+
+
+
+
+
+bool cWorld::IsSlimeChunk(int a_ChunkX, int a_ChunkZ) const
+{
+	cNoise Noise(GetSeed());
+	return (Noise.IntNoise2DInt(a_ChunkX, a_ChunkZ) / 8) % 10 == 0;  // 10% chance
+}

src/World.h

@@ -843,7 +843,7 @@ public:
 	virtual bool IsWeatherWetAtXYZ(Vector3i a_Position) override;
 
 	/** Returns the seed of the world. */
-	int GetSeed(void) { return m_Generator.GetSeed(); }
+	int GetSeed(void) const { return m_Generator.GetSeed(); }
 
 	// tolua_end
 
@@ -892,6 +892,8 @@ public:
 	as at least one requests is active the chunk will be ticked). */
 	void SetChunkAlwaysTicked(int a_ChunkX, int a_ChunkZ, bool a_AlwaysTicked = true);  // tolua_export
 
+	/** Returns true if slimes should spawn in the chunk. */
+	bool IsSlimeChunk(int a_ChunkX, int a_ChunkZ) const;  // tolua_export
 private:
 
 	class cTickThread: