6 files changed, 242 insertions, 10 deletions

diff --git a/MCServer/Plugins/APIDump/APIDesc.lua b/MCServer/Plugins/APIDump/APIDesc.lua
index a3695fe17..7c9a2e0cb 100644
--- a/MCServer/Plugins/APIDump/APIDesc.lua
+++ b/MCServer/Plugins/APIDump/APIDesc.lua
@@ -120,6 +120,7 @@ g_APIDesc =
 				GetOriginX = { Params = "", Return = "number", Notes = "Returns the origin x-coord" },
 				GetOriginY = { Params = "", Return = "number", Notes = "Returns the origin y-coord" },
 				GetOriginZ = { Params = "", Return = "number", Notes = "Returns the origin z-coord" },
+				GetNonAirCropRelCoords = { Params = "[IgnoreBlockType]", Return = "MinRelX, MinRelY, MinRelZ, MaxRelX, MaxRelY, MaxRelZ", Notes = "Returns the minimum and maximum coords in each direction for the first non-ignored block in each direction. If there are no non-ignored blocks within the area, or blocktypes are not present, the returned values are reverse-ranges (MinX <- m_RangeX, MaxX <- 0 etc.). IgnoreBlockType defaults to air." },
 				GetRelBlockLight = { Params = "RelBlockX, RelBlockY, RelBlockZ", Return = "NIBBLETYPE", Notes = "Returns the blocklight at the specified relative coords" },
 				GetRelBlockMeta = { Params = "RelBlockX, RelBlockY, RelBlockZ", Return = "NIBBLETYPE", Notes = "Returns the block meta at the specified relative coords" },
 				GetRelBlockSkyLight = { Params = "RelBlockX, RelBlockY, RelBlockZ", Return = "NIBBLETYPE", Notes = "Returns the skylight at the specified relative coords" },
@@ -197,13 +198,14 @@ g_APIDesc =
 				baMetas = { Notes = "Operations should work on block metas" },
 				baLight = { Notes = "Operations should work on block (emissive) light" },
 				baSkyLight = { Notes = "Operations should work on skylight" },
-				msDifference = { Notes = "Block becomes air if Src and Dst are the same. Otherwise it becomes the source block." },
-				msOverwrite = { Notes = "Src overwrites anything in Dst" },
-				msFillAir = { Notes = "Dst is overwritten by Src only where Src has air blocks" },
-				msImprint = { Notes = "Src overwrites Dst anywhere where Dst has non-air blocks" },
+				msDifference = { Notes = "Block becomes air if 'self' and src are the same. Otherwise it becomes the src block." },
+				msFillAir = { Notes = "'self' is overwritten by Src only where 'self' has air blocks" },
+				msImprint = { Notes = "Src overwrites 'self' anywhere where 'self' has non-air blocks" },
 				msLake = { Notes = "Special mode for merging lake images" },
+				msMask = { Notes = "The blocks that are exactly the same are kept in 'self', all differing blocks are replaced by air"},
+				msOverwrite = { Notes = "Src overwrites anything in 'self'" },
+				msSimpleCompare = { Notes = "The blocks that are exactly the same are replaced with air, all differing blocks are replaced by stone"},
 				msSpongePrint = { Notes = "Similar to msImprint, sponge block doesn't overwrite anything, all other blocks overwrite everything"},
-				msMask = { Notes = "The blocks that are exactly the same are kept in Dst, all differing blocks are replaced by air"},
 			},
 			ConstantGroups =
 			{
@@ -287,7 +289,7 @@ g_APIDesc =
 						<table><tbody><tr>
 						<th colspan="2"> area block </th><th> </th><th> Notes </th>
 						</tr><tr>
-						<th> this </th><th> Src </th><th> result </th><th> </th>
+						<th> self </th><th> Src </th><th> result </th><th> </th>
 						</tr><tr>
 						<td> A </td><td> sponge </td><td> A </td><td> Sponge is the NOP block </td>
 						</tr><tr>
@@ -321,7 +323,7 @@ g_APIDesc =
 						<table><tbody><tr>
 						<th colspan="2"> area block </th><th> </th><th> Notes </th>
 						</tr><tr>
-						<th> this </th><th> Src </th><th> result </th><th> </th>
+						<th> self </th><th> Src </th><th> result </th><th> </th>
 						</tr><tr>
 						<td> A </td><td> sponge </td><td> A </td><td> Sponge is the NOP block </td>
 						</tr><tr>
@@ -337,13 +339,45 @@ g_APIDesc =
 						<table><tbody><tr>
 						<th colspan="2"> area block </th><th> </th><th> Notes </th>
 						</tr><tr>
-						<th> this </th><th> Src </th><th> result </th><th> </th>
+						<th> self </th><th> Src </th><th> result </th><th> </th>
 						</tr><tr>
 						<td> A </td><td> A </td><td> A </td><td> Same blocks are kept </td>
 						</tr><tr>
 						<td> A </td><td> non-A </td><td> air </td><td> Differing blocks are replaced with air </td>
 						</tr>
 						</tbody></table>
+
+						<p>
+						<strong>msDifference</strong> - the blocks that are the same in both areas are replaced with air, all the
+						differing blocks are kept from the first area. Meta is used in the comparison, too, two blocks of the
+						same type but different meta are considered different.
+						</p>
+						<table><tbody><tr>
+						<th colspan="2"> area block </th><th> </th><th> Notes </th>
+						</tr><tr>
+						<th> self </th><th> Src </th><th> result </th><th> </th>
+						</tr><tr>
+						<td> A </td><td> A </td><td> air </td><td> Same blocks are replaced with air </td>
+						</tr><tr>
+						<td> A </td><td> non-A </td><td> A </td><td> Differing blocks are kept from 'self' </td>
+						</tr>
+						</tbody></table>
+						
+						<p>
+						<strong>msSimpleCompare</strong> - the blocks that are the same in both areas are replaced with air, all the
+						differing blocks are replaced with stone. Meta is used in the comparison, too, two blocks of the
+						same type but different meta are considered different.
+						</p>
+						<table><tbody><tr>
+						<th colspan="2"> area block </th><th> </th><th> Notes </th>
+						</tr><tr>
+						<th> self </th><th> Src </th><th> result </th><th> </th>
+						</tr><tr>
+						<td> A </td><td> A </td><td> air </td><td> Same blocks are replaced with air </td>
+						</tr><tr>
+						<td> A </td><td> non-A </td><td> stone </td><td> Differing blocks are replaced with stone </td>
+						</tr>
+						</tbody></table>
 ]],
 				},  -- Merge strategies
 			},  -- AdditionalInfo
diff --git a/src/Bindings/LuaState.cpp b/src/Bindings/LuaState.cpp
index 38e008b2a..ed31e678f 100644
--- a/src/Bindings/LuaState.cpp
+++ b/src/Bindings/LuaState.cpp
@@ -937,6 +937,18 @@ void cLuaState::GetStackValue(int a_StackPos, AString & a_Value)
 
 
 
+void cLuaState::GetStackValue(int a_StackPos, BLOCKTYPE & a_ReturnedVal)
+{
+	if (lua_isnumber(m_LuaState, a_StackPos))
+	{
+		a_ReturnedVal = static_cast<BLOCKTYPE>(tolua_tonumber(m_LuaState, a_StackPos, a_ReturnedVal));
+	}
+}
+
+
+
+
+
 void cLuaState::GetStackValue(int a_StackPos, bool & a_ReturnedVal)
 {
 	a_ReturnedVal = (tolua_toboolean(m_LuaState, a_StackPos, a_ReturnedVal ? 1 : 0) > 0);
@@ -995,6 +1007,24 @@ void cLuaState::GetStackValue(int a_StackPos, int & a_ReturnedVal)
 
 
 
+void cLuaState::GetStackValue(int a_StackPos, pBlockArea & a_ReturnedVal)
+{
+	if (lua_isnil(m_LuaState, a_StackPos))
+	{
+		a_ReturnedVal = nullptr;
+		return;
+	}
+	tolua_Error err;
+	if (tolua_isusertype(m_LuaState, a_StackPos, "cBlockArea", false, &err))
+	{
+		a_ReturnedVal = *(reinterpret_cast<cBlockArea **>(lua_touserdata(m_LuaState, a_StackPos)));
+	}
+}
+
+
+
+
+
 void cLuaState::GetStackValue(int a_StackPos, pBoundingBox & a_ReturnedVal)
 {
 	if (lua_isnil(m_LuaState, a_StackPos))
@@ -1005,7 +1035,7 @@ void cLuaState::GetStackValue(int a_StackPos, pBoundingBox & a_ReturnedVal)
 	tolua_Error err;
 	if (tolua_isusertype(m_LuaState, a_StackPos, "cBoundingBox", false, &err))
 	{
-		a_ReturnedVal = *((cBoundingBox **)lua_touserdata(m_LuaState, a_StackPos));
+		a_ReturnedVal = *(reinterpret_cast<cBoundingBox **>(lua_touserdata(m_LuaState, a_StackPos)));
 	}
 }
 
diff --git a/src/Bindings/LuaState.h b/src/Bindings/LuaState.h
index a6e121eb7..6bedbf5ec 100644
--- a/src/Bindings/LuaState.h
+++ b/src/Bindings/LuaState.h
@@ -37,6 +37,7 @@ extern "C"
 
 
 
+class cBlockArea;
 class cBlockEntity;
 class cBoundingBox;
 class cChunkDesc;
@@ -68,6 +69,7 @@ struct HTTPRequest;
 struct HTTPTemplateRequest;
 struct TakeDamageInfo;
 
+typedef cBlockArea *     pBlockArea;
 typedef cBoundingBox *   pBoundingBox;
 typedef cMapManager *    pMapManager;
 typedef cPluginManager * pPluginManager;
@@ -244,11 +246,13 @@ public:
 	// GetStackValue() retrieves the value at a_StackPos, if it is a valid type. If not, a_Value is unchanged.
 	// Enum values are clamped to their allowed range.
 	void GetStackValue(int a_StackPos, AString & a_Value);
+	void GetStackValue(int a_StackPos, BLOCKTYPE & a_Value);
 	void GetStackValue(int a_StackPos, bool & a_Value);
 	void GetStackValue(int a_StackPos, cRef & a_Ref);
 	void GetStackValue(int a_StackPos, double & a_Value);
 	void GetStackValue(int a_StackPos, eWeather & a_Value);
 	void GetStackValue(int a_StackPos, int & a_Value);
+	void GetStackValue(int a_StackPos, pBlockArea & a_Value);
 	void GetStackValue(int a_StackPos, pBoundingBox & a_Value);
 	void GetStackValue(int a_StackPos, pMapManager & a_Value);
 	void GetStackValue(int a_StackPos, pPluginManager & a_Value);
diff --git a/src/Bindings/ManualBindings.cpp b/src/Bindings/ManualBindings.cpp
index c4b12aa84..8e909827c 100644
--- a/src/Bindings/ManualBindings.cpp
+++ b/src/Bindings/ManualBindings.cpp
@@ -3187,6 +3187,44 @@ static int tolua_cBlockArea_GetOrigin(lua_State * tolua_S)
 
 
 
+static int tolua_cBlockArea_GetNonAirCropRelCoords(lua_State * tolua_S)
+{
+	// function cBlockArea::GetNonAirCropRelCoords()
+	// Exported manually because tolua would generate extra input params for the outputs
+	
+	cLuaState L(tolua_S);
+	if (!L.CheckParamUserType(1, "cBlockArea"))
+	{
+		return 0;
+	}
+	
+	cBlockArea * self = nullptr;
+	BLOCKTYPE IgnoreBlockType = E_BLOCK_AIR;
+	L.GetStackValues(1, self, IgnoreBlockType);
+	if (self == nullptr)
+	{
+		tolua_error(tolua_S, "invalid 'self' in function 'cBlockArea:GetNonAirCropRelCoords'", nullptr);
+		return 0;
+	}
+	
+	// Calculate the crop coords:
+	int MinRelX, MinRelY, MinRelZ, MaxRelX, MaxRelY, MaxRelZ;
+	self->GetNonAirCropRelCoords(MinRelX, MinRelY, MinRelZ, MaxRelX, MaxRelY, MaxRelZ, IgnoreBlockType);
+
+	// Push the six crop coords:
+	L.Push(MinRelX);
+	L.Push(MinRelY);
+	L.Push(MinRelZ);
+	L.Push(MaxRelX);
+	L.Push(MaxRelY);
+	L.Push(MaxRelZ);
+	return 6;
+}
+
+
+
+
+
 static int tolua_cBlockArea_GetRelBlockTypeMeta(lua_State * tolua_S)
 {
 	// function cBlockArea::GetRelBlockTypeMeta()
@@ -3687,6 +3725,7 @@ void ManualBindings::Bind(lua_State * tolua_S)
 			tolua_function(tolua_S, "GetBlockTypeMeta",        tolua_cBlockArea_GetBlockTypeMeta);
 			tolua_function(tolua_S, "GetCoordRange",           tolua_cBlockArea_GetCoordRange);
 			tolua_function(tolua_S, "GetOrigin",               tolua_cBlockArea_GetOrigin);
+			tolua_function(tolua_S, "GetNonAirCropRelCoords",  tolua_cBlockArea_GetNonAirCropRelCoords);
 			tolua_function(tolua_S, "GetRelBlockTypeMeta",     tolua_cBlockArea_GetRelBlockTypeMeta);
 			tolua_function(tolua_S, "GetSize",                 tolua_cBlockArea_GetSize);
 			tolua_function(tolua_S, "LoadFromSchematicFile",   tolua_cBlockArea_LoadFromSchematicFile);
diff --git a/src/BlockArea.cpp b/src/BlockArea.cpp
index 4c3da0535..600940d96 100644
--- a/src/BlockArea.cpp
+++ b/src/BlockArea.cpp
@@ -245,6 +245,26 @@ void MergeCombinatorDifference(BLOCKTYPE & a_DstType, BLOCKTYPE a_SrcType, NIBBL
 
 
 
+/** Combinator used for cBlockArea::msSimpleCompare merging */
+template <bool MetaValid>
+void MergeCombinatorSimpleCompare(BLOCKTYPE & a_DstType, BLOCKTYPE a_SrcType, NIBBLETYPE & a_DstMeta, NIBBLETYPE a_SrcMeta)
+{
+	if ((a_DstType == a_SrcType) && (!MetaValid || (a_DstMeta == a_SrcMeta)))
+	{
+		// The blocktypes are the same, and the blockmetas are not present or are the same
+		a_DstType = E_BLOCK_AIR;
+	}
+	else
+	{
+		// The blocktypes or blockmetas differ
+		a_DstType = E_BLOCK_STONE;
+	}
+}
+
+
+
+
+
 /** Combinator used for cBlockArea::msMask merging */
 template <bool MetaValid>
 void MergeCombinatorMask(BLOCKTYPE & a_DstType, BLOCKTYPE a_SrcType, NIBBLETYPE & a_DstMeta, NIBBLETYPE a_SrcMeta)
@@ -1614,6 +1634,73 @@ void cBlockArea::GetRelBlockTypeMeta(int a_RelX, int a_RelY, int a_RelZ, BLOCKTY
 
 
 
+void cBlockArea::GetNonAirCropRelCoords(int & a_MinRelX, int & a_MinRelY, int & a_MinRelZ, int & a_MaxRelX, int & a_MaxRelY, int & a_MaxRelZ, BLOCKTYPE a_IgnoreBlockType)
+{
+	// Check if blocktypes are valid:
+	if (m_BlockTypes == nullptr)
+	{
+		LOGWARNING("%s: BlockTypes have not been read!", __FUNCTION__);
+		a_MinRelX = 1;
+		a_MaxRelX = 0;
+		return;
+	}
+
+	// Walk all the blocks and find the min and max coords for the non-ignored ones:
+	int MaxX = 0, MinX = m_Size.x - 1;
+	int MaxY = 0, MinY = m_Size.y - 1;
+	int MaxZ = 0, MinZ = m_Size.z - 1;
+	for (int y = 0; y < m_Size.y; y++)
+	{
+		for (int z = 0; z < m_Size.z; z++)
+		{
+			for (int x = 0; x < m_Size.x; x++)
+			{
+				if (m_BlockTypes[MakeIndex(x, y, z)] == a_IgnoreBlockType)
+				{
+					continue;
+				}
+				// The block is not ignored, update any coords that need updating:
+				if (x < MinX)
+				{
+					MinX = x;
+				}
+				if (x > MaxX)
+				{
+					MaxX = x;
+				}
+				if (y < MinY)
+				{
+					MinY = y;
+				}
+				if (y > MaxY)
+				{
+					MaxY = y;
+				}
+				if (z < MinZ)
+				{
+					MinZ = z;
+				}
+				if (z > MaxZ)
+				{
+					MaxZ = z;
+				}
+			}  // for x
+		}  // for z
+	}  // for y
+
+	// Assign to the output:
+	a_MinRelX = MinX;
+	a_MinRelY = MinY;
+	a_MinRelZ = MinZ;
+	a_MaxRelX = MaxX;
+	a_MaxRelY = MaxY;
+	a_MaxRelZ = MaxZ;
+}
+
+
+
+
+
 int cBlockArea::GetDataTypes(void) const
 {
 	int res = 0;
@@ -2121,10 +2208,12 @@ void cBlockArea::RelSetData(
 
 
 
+
+
 template <bool MetasValid>
 void cBlockArea::MergeByStrategy(const cBlockArea & a_Src, int a_RelX, int a_RelY, int a_RelZ, eMergeStrategy a_Strategy, const NIBBLETYPE * SrcMetas, NIBBLETYPE * DstMetas)
 {
-	// Block types are compulsory, block metas are voluntary
+	// Block types are compulsory, block metas are optional
 	if (!HasBlockTypes() || !a_Src.HasBlockTypes())
 	{
 		LOGWARNING("%s: cannot merge because one of the areas doesn't have blocktypes.", __FUNCTION__);
@@ -2230,6 +2319,20 @@ void cBlockArea::MergeByStrategy(const cBlockArea & a_Src, int a_RelX, int a_Rel
 			return;
 		}  // case msDifference
 		
+		case cBlockArea::msSimpleCompare:
+		{
+			InternalMergeBlocks<MetasValid, MergeCombinatorSimpleCompare<MetasValid> >(
+				m_BlockTypes, a_Src.GetBlockTypes(),
+				DstMetas, SrcMetas,
+				SizeX, SizeY, SizeZ,
+				SrcOffX, SrcOffY, SrcOffZ,
+				DstOffX, DstOffY, DstOffZ,
+				a_Src.GetSizeX(), a_Src.GetSizeY(), a_Src.GetSizeZ(),
+				m_Size.x, m_Size.y, m_Size.z
+			);
+			return;
+		}  // case msSimpleCompare
+		
 		case cBlockArea::msMask:
 		{
 			InternalMergeBlocks<MetasValid, MergeCombinatorMask<MetasValid> >(
diff --git a/src/BlockArea.h b/src/BlockArea.h
index 348e960dd..ce417ceb4 100644
--- a/src/BlockArea.h
+++ b/src/BlockArea.h
@@ -54,6 +54,7 @@ public:
 		msLake,
 		msSpongePrint,
 		msDifference,
+		msSimpleCompare,
 		msMask,
 	} ;
 	
@@ -156,6 +157,22 @@ public:
 	| A        | sponge | A      |  Sponge is the NOP block
 	| *        | B      | B      |  Everything else overwrites anything
 	
+	msDifference:
+	Used to determine the differences between two areas. Only the differring blocks are preserved:
+	|  area block  |        |
+	| this | Src   | result |
+	+------+-------+--------+
+	| A    | A     | air    |  Same blocks are replaced with air
+	| A    | non-A | A      |  Differring blocks are kept from "this"
+
+	msSimpleCompare:
+	Used to determine the differences between two areas. Blocks that differ are replaced with stone, same blocks are replaced with air
+	|  area block  |        |
+	| this | Src   | result |
+	+------+-------+--------+
+	| A    | A     | air    |  Same blocks are replaced with air
+	| A    | non-A | stone  |  Differring blocks are replaced with stone
+
 	msMask:
 	Combines two areas, the blocks that are the same are kept, differing ones are reset to air
 	|  area block  |        |
@@ -288,6 +305,11 @@ public:
 	bool HasBlockSkyLights(void) const { return (m_BlockSkyLight != nullptr); }
 	
 	// tolua_end
+
+	/** Returns the minimum and maximum coords in each direction for the first non-ignored block in each direction.
+	If there are no non-ignored blocks within the area, or blocktypes are not present, the returned values are reverse-ranges (MinX <- m_RangeX, MaxX <- 0 etc.)
+	Exported to Lua in ManualBindings.cpp. */
+	void GetNonAirCropRelCoords(int & a_MinRelX, int & a_MinRelY, int & a_MinRelZ, int & a_MaxRelX, int & a_MaxRelY, int & a_MaxRelZ, BLOCKTYPE a_IgnoreBlockType = E_BLOCK_AIR);
 	
 	// Clients can use these for faster access to all blocktypes. Be careful though!
 	/** Returns the internal pointer to the block types */