Added new merge strategy "msDifference"

src/BlockArea.cpp

@@ -173,6 +173,25 @@ static inline void MergeCombinatorSpongePrint(BLOCKTYPE & a_DstType, BLOCKTYPE a
 
 
 
+/** Combinator used for cBlockArea::msDifference merging */
+static inline void MergeCombinatorDifference(BLOCKTYPE & a_DstType, BLOCKTYPE a_SrcType, NIBBLETYPE & a_DstMeta, NIBBLETYPE a_SrcMeta)
+{
+	if ((a_DstType == a_SrcType) && (a_DstMeta == a_SrcMeta))
+	{
+		a_DstType = E_BLOCK_AIR;
+		a_DstMeta = 0;
+	}
+	else
+	{
+		a_DstType = a_SrcType;
+		a_DstMeta = a_SrcMeta;
+	}
+}
+
+
+
+
+
 ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 // cBlockArea:
 
@@ -710,6 +729,21 @@ void cBlockArea::Merge(const cBlockArea & a_Src, int a_RelX, int a_RelY, int a_R
 			break;
 		}  // case msSpongePrint
 
+		case msDifference:
+		{
+			InternalMergeBlocks(
+				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,
+				MergeCombinatorDifference
+			);
+			break;
+		}	// case msDifference
+		
 		default:
 		{
 			LOGWARNING("Unknown block area merge strategy: %d", a_Strategy);

src/BlockArea.h

@@ -52,6 +52,7 @@ public:
 		msImprint,
 		msLake,
 		msSpongePrint,
+		msDifference,
 	} ;
 	
 	cBlockArea(void);