1 files changed, 593 insertions, 100 deletions

diff --git a/extern/recastnavigation/Recast/Source/RecastRegion.cpp b/extern/recastnavigation/Recast/Source/RecastRegion.cpp
index 4290972ed24..54acf4b736b 100644
--- a/extern/recastnavigation/Recast/Source/RecastRegion.cpp
+++ b/extern/recastnavigation/Recast/Source/RecastRegion.cpp
@@ -286,7 +286,10 @@ static bool floodRegion(int x, int y, int i,
 				if (nr & RC_BORDER_REG) // Do not take borders into account.
 					continue;
 				if (nr != 0 && nr != r)
+				{
 					ar = nr;
+					break;
+				}
 				
 				const rcCompactSpan& as = chf.spans[ai];
 				
@@ -298,9 +301,12 @@ static bool floodRegion(int x, int y, int i,
 					const int ai2 = (int)chf.cells[ax2+ay2*w].index + rcGetCon(as, dir2);
 					if (chf.areas[ai2] != area)
 						continue;
-					unsigned short nr = srcReg[ai2];
-					if (nr != 0 && nr != r)
-						ar = nr;
+					unsigned short nr2 = srcReg[ai2];
+					if (nr2 != 0 && nr2 != r)
+					{
+						ar = nr2;
+						break;
+					}
 				}				
 			}
 		}
@@ -309,6 +315,7 @@ static bool floodRegion(int x, int y, int i,
 			srcReg[ci] = 0;
 			continue;
 		}
+		
 		count++;
 		
 		// Expand neighbours.
@@ -340,30 +347,44 @@ static unsigned short* expandRegions(int maxIter, unsigned short level,
 									 rcCompactHeightfield& chf,
 									 unsigned short* srcReg, unsigned short* srcDist,
 									 unsigned short* dstReg, unsigned short* dstDist, 
-									 rcIntArray& stack)
+									 rcIntArray& stack,
+									 bool fillStack)
 {
 	const int w = chf.width;
 	const int h = chf.height;
 
-	// Find cells revealed by the raised level.
-	stack.resize(0);
-	for (int y = 0; y < h; ++y)
+	if (fillStack)
 	{
-		for (int x = 0; x < w; ++x)
+		// Find cells revealed by the raised level.
+		stack.resize(0);
+		for (int y = 0; y < h; ++y)
 		{
-			const rcCompactCell& c = chf.cells[x+y*w];
-			for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i)
+			for (int x = 0; x < w; ++x)
 			{
-				if (chf.dist[i] >= level && srcReg[i] == 0 && chf.areas[i] != RC_NULL_AREA)
+				const rcCompactCell& c = chf.cells[x+y*w];
+				for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i)
 				{
-					stack.push(x);
-					stack.push(y);
-					stack.push(i);
+					if (chf.dist[i] >= level && srcReg[i] == 0 && chf.areas[i] != RC_NULL_AREA)
+					{
+						stack.push(x);
+						stack.push(y);
+						stack.push(i);
+					}
 				}
 			}
 		}
 	}
-	
+	else // use cells in the input stack
+	{
+		// mark all cells which already have a region
+		for (int j=0; j<stack.size(); j+=3)
+		{
+			int i = stack[j+2];
+			if (srcReg[i] != 0)
+				stack[j+2] = -1;
+		}
+	}
+
 	int iter = 0;
 	while (stack.size() > 0)
 	{
@@ -434,6 +455,61 @@ static unsigned short* expandRegions(int maxIter, unsigned short level,
 }
 
 
+
+static void sortCellsByLevel(unsigned short startLevel,
+							  rcCompactHeightfield& chf,
+							  unsigned short* srcReg,
+							  unsigned int nbStacks, rcIntArray* stacks,
+							  unsigned short loglevelsPerStack) // the levels per stack (2 in our case) as a bit shift
+{
+	const int w = chf.width;
+	const int h = chf.height;
+	startLevel = startLevel >> loglevelsPerStack;
+
+	for (unsigned int j=0; j<nbStacks; ++j)
+		stacks[j].resize(0);
+
+	// put all cells in the level range into the appropriate stacks
+	for (int y = 0; y < h; ++y)
+	{
+		for (int x = 0; x < w; ++x)
+		{
+			const rcCompactCell& c = chf.cells[x+y*w];
+			for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i)
+			{
+				if (chf.areas[i] == RC_NULL_AREA || srcReg[i] != 0)
+					continue;
+
+				int level = chf.dist[i] >> loglevelsPerStack;
+				int sId = startLevel - level;
+				if (sId >= (int)nbStacks)
+					continue;
+				if (sId < 0)
+					sId = 0;
+
+				stacks[sId].push(x);
+				stacks[sId].push(y);
+				stacks[sId].push(i);
+			}
+		}
+	}
+}
+
+
+static void appendStacks(rcIntArray& srcStack, rcIntArray& dstStack,
+						 unsigned short* srcReg)
+{
+	for (int j=0; j<srcStack.size(); j+=3)
+	{
+		int i = srcStack[j+2];
+		if ((i < 0) || (srcReg[i] != 0))
+			continue;
+		dstStack.push(srcStack[j]);
+		dstStack.push(srcStack[j+1]);
+		dstStack.push(srcStack[j+2]);
+	}
+}
+
 struct rcRegion
 {
 	inline rcRegion(unsigned short i) :
@@ -441,7 +517,11 @@ struct rcRegion
 		id(i),
 		areaType(0),
 		remap(false),
-		visited(false)
+		visited(false),
+		overlap(false),
+		connectsToBorder(false),
+		ymin(0xffff),
+		ymax(0)
 	{}
 	
 	int spanCount;					// Number of spans belonging to this region
@@ -449,6 +529,9 @@ struct rcRegion
 	unsigned char areaType;			// Are type.
 	bool remap;
 	bool visited;
+	bool overlap;
+	bool connectsToBorder;
+	unsigned short ymin, ymax;
 	rcIntArray connections;
 	rcIntArray floors;
 };
@@ -678,25 +761,26 @@ static void walkContour(int x, int y, int i, int dir,
 	// Remove adjacent duplicates.
 	if (cont.size() > 1)
 	{
-		for (int i = 0; i < cont.size(); )
+		for (int j = 0; j < cont.size(); )
 		{
-			int ni = (i+1) % cont.size();
-			if (cont[i] == cont[ni])
+			int nj = (j+1) % cont.size();
+			if (cont[j] == cont[nj])
 			{
-				for (int j = i; j < cont.size()-1; ++j)
-					cont[j] = cont[j+1];
+				for (int k = j; k < cont.size()-1; ++k)
+					cont[k] = cont[k+1];
 				cont.pop();
 			}
 			else
-				++i;
+				++j;
 		}
 	}
 }
 
-static bool filterSmallRegions(rcContext* ctx, int minRegionArea, int mergeRegionSize,
-							   unsigned short& maxRegionId,
-							   rcCompactHeightfield& chf,
-							   unsigned short* srcReg)
+
+static bool mergeAndFilterRegions(rcContext* ctx, int minRegionArea, int mergeRegionSize,
+								  unsigned short& maxRegionId,
+								  rcCompactHeightfield& chf,
+								  unsigned short* srcReg, rcIntArray& overlaps)
 {
 	const int w = chf.width;
 	const int h = chf.height;
@@ -705,7 +789,7 @@ static bool filterSmallRegions(rcContext* ctx, int minRegionArea, int mergeRegio
 	rcRegion* regions = (rcRegion*)rcAlloc(sizeof(rcRegion)*nreg, RC_ALLOC_TEMP);
 	if (!regions)
 	{
-		ctx->log(RC_LOG_ERROR, "filterSmallRegions: Out of memory 'regions' (%d).", nreg);
+		ctx->log(RC_LOG_ERROR, "mergeAndFilterRegions: Out of memory 'regions' (%d).", nreg);
 		return false;
 	}
 
@@ -728,7 +812,6 @@ static bool filterSmallRegions(rcContext* ctx, int minRegionArea, int mergeRegio
 				rcRegion& reg = regions[r];
 				reg.spanCount++;
 				
-				
 				// Update floors.
 				for (int j = (int)c.index; j < ni; ++j)
 				{
@@ -736,6 +819,8 @@ static bool filterSmallRegions(rcContext* ctx, int minRegionArea, int mergeRegio
 					unsigned short floorId = srcReg[j];
 					if (floorId == 0 || floorId >= nreg)
 						continue;
+					if (floorId == r)
+						reg.overlap = true;
 					addUniqueFloorRegion(reg, floorId);
 				}
 				
@@ -806,14 +891,14 @@ static bool filterSmallRegions(rcContext* ctx, int minRegionArea, int mergeRegio
 					connectsToBorder = true;
 					continue;
 				}
-				rcRegion& nreg = regions[creg.connections[j]];
-				if (nreg.visited)
+				rcRegion& neireg = regions[creg.connections[j]];
+				if (neireg.visited)
 					continue;
-				if (nreg.id == 0 || (nreg.id & RC_BORDER_REG))
+				if (neireg.id == 0 || (neireg.id & RC_BORDER_REG))
 					continue;
 				// Visit
-				stack.push(nreg.id);
-				nreg.visited = true;
+				stack.push(neireg.id);
+				neireg.visited = true;
 			}
 		}
 		
@@ -831,7 +916,7 @@ static bool filterSmallRegions(rcContext* ctx, int minRegionArea, int mergeRegio
 			}
 		}
 	}
-		
+	
 	// Merge too small regions to neighbour regions.
 	int mergeCount = 0 ;
 	do
@@ -841,7 +926,9 @@ static bool filterSmallRegions(rcContext* ctx, int minRegionArea, int mergeRegio
 		{
 			rcRegion& reg = regions[i];
 			if (reg.id == 0 || (reg.id & RC_BORDER_REG))
-				continue;                       
+				continue;
+			if (reg.overlap)
+				continue;
 			if (reg.spanCount == 0)
 				continue;
 			
@@ -858,7 +945,7 @@ static bool filterSmallRegions(rcContext* ctx, int minRegionArea, int mergeRegio
 			{
 				if (reg.connections[j] & RC_BORDER_REG) continue;
 				rcRegion& mreg = regions[reg.connections[j]];
-				if (mreg.id == 0 || (mreg.id & RC_BORDER_REG)) continue;
+				if (mreg.id == 0 || (mreg.id & RC_BORDER_REG) || mreg.overlap) continue;
 				if (mreg.spanCount < smallest &&
 					canMergeWithRegion(reg, mreg) &&
 					canMergeWithRegion(mreg, reg))
@@ -928,6 +1015,224 @@ static bool filterSmallRegions(rcContext* ctx, int minRegionArea, int mergeRegio
 		if ((srcReg[i] & RC_BORDER_REG) == 0)
 			srcReg[i] = regions[srcReg[i]].id;
 	}
+
+	// Return regions that we found to be overlapping.
+	for (int i = 0; i < nreg; ++i)
+		if (regions[i].overlap)
+			overlaps.push(regions[i].id);
+
+	for (int i = 0; i < nreg; ++i)
+		regions[i].~rcRegion();
+	rcFree(regions);
+	
+	
+	return true;
+}
+
+
+static void addUniqueConnection(rcRegion& reg, int n)
+{
+	for (int i = 0; i < reg.connections.size(); ++i)
+		if (reg.connections[i] == n)
+			return;
+	reg.connections.push(n);
+}
+
+static bool mergeAndFilterLayerRegions(rcContext* ctx, int minRegionArea,
+									   unsigned short& maxRegionId,
+									   rcCompactHeightfield& chf,
+									   unsigned short* srcReg, rcIntArray& /*overlaps*/)
+{
+	const int w = chf.width;
+	const int h = chf.height;
+	
+	const int nreg = maxRegionId+1;
+	rcRegion* regions = (rcRegion*)rcAlloc(sizeof(rcRegion)*nreg, RC_ALLOC_TEMP);
+	if (!regions)
+	{
+		ctx->log(RC_LOG_ERROR, "mergeAndFilterLayerRegions: Out of memory 'regions' (%d).", nreg);
+		return false;
+	}
+	
+	// Construct regions
+	for (int i = 0; i < nreg; ++i)
+		new(&regions[i]) rcRegion((unsigned short)i);
+	
+	// Find region neighbours and overlapping regions.
+	rcIntArray lregs(32);
+	for (int y = 0; y < h; ++y)
+	{
+		for (int x = 0; x < w; ++x)
+		{
+			const rcCompactCell& c = chf.cells[x+y*w];
+
+			lregs.resize(0);
+			
+			for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i)
+			{
+				const rcCompactSpan& s = chf.spans[i];
+				const unsigned short ri = srcReg[i];
+				if (ri == 0 || ri >= nreg) continue;
+				rcRegion& reg = regions[ri];
+				
+				reg.spanCount++;
+				
+				reg.ymin = rcMin(reg.ymin, s.y);
+				reg.ymax = rcMax(reg.ymax, s.y);
+				
+				// Collect all region layers.
+				lregs.push(ri);
+				
+				// Update neighbours
+				for (int dir = 0; dir < 4; ++dir)
+				{
+					if (rcGetCon(s, dir) != RC_NOT_CONNECTED)
+					{
+						const int ax = x + rcGetDirOffsetX(dir);
+						const int ay = y + rcGetDirOffsetY(dir);
+						const int ai = (int)chf.cells[ax+ay*w].index + rcGetCon(s, dir);
+						const unsigned short rai = srcReg[ai];
+						if (rai > 0 && rai < nreg && rai != ri)
+							addUniqueConnection(reg, rai);
+						if (rai & RC_BORDER_REG)
+							reg.connectsToBorder = true;
+					}
+				}
+				
+			}
+			
+			// Update overlapping regions.
+			for (int i = 0; i < lregs.size()-1; ++i)
+			{
+				for (int j = i+1; j < lregs.size(); ++j)
+				{
+					if (lregs[i] != lregs[j])
+					{
+						rcRegion& ri = regions[lregs[i]];
+						rcRegion& rj = regions[lregs[j]];
+						addUniqueFloorRegion(ri, lregs[j]);
+						addUniqueFloorRegion(rj, lregs[i]);
+					}
+				}
+			}
+			
+		}
+	}
+
+	// Create 2D layers from regions.
+	unsigned short layerId = 1;
+
+	for (int i = 0; i < nreg; ++i)
+		regions[i].id = 0;
+
+	// Merge montone regions to create non-overlapping areas.
+	rcIntArray stack(32);
+	for (int i = 1; i < nreg; ++i)
+	{
+		rcRegion& root = regions[i];
+		// Skip already visited.
+		if (root.id != 0)
+			continue;
+		
+		// Start search.
+		root.id = layerId;
+
+		stack.resize(0);
+		stack.push(i);
+		
+		while (stack.size() > 0)
+		{
+			// Pop front
+			rcRegion& reg = regions[stack[0]];
+			for (int j = 0; j < stack.size()-1; ++j)
+				stack[j] = stack[j+1];
+			stack.resize(stack.size()-1);
+			
+			const int ncons = (int)reg.connections.size();
+			for (int j = 0; j < ncons; ++j)
+			{
+				const int nei = reg.connections[j];
+				rcRegion& regn = regions[nei];
+				// Skip already visited.
+				if (regn.id != 0)
+					continue;
+				// Skip if the neighbour is overlapping root region.
+				bool overlap = false;
+				for (int k = 0; k < root.floors.size(); k++)
+				{
+					if (root.floors[k] == nei)
+					{
+						overlap = true;
+						break;
+					}
+				}
+				if (overlap)
+					continue;
+					
+				// Deepen
+				stack.push(nei);
+					
+				// Mark layer id
+				regn.id = layerId;
+				// Merge current layers to root.
+				for (int k = 0; k < regn.floors.size(); ++k)
+					addUniqueFloorRegion(root, regn.floors[k]);
+				root.ymin = rcMin(root.ymin, regn.ymin);
+				root.ymax = rcMax(root.ymax, regn.ymax);
+				root.spanCount += regn.spanCount;
+				regn.spanCount = 0;
+				root.connectsToBorder = root.connectsToBorder || regn.connectsToBorder;
+			}
+		}
+		
+		layerId++;
+	}
+	
+	// Remove small regions
+	for (int i = 0; i < nreg; ++i)
+	{
+		if (regions[i].spanCount > 0 && regions[i].spanCount < minRegionArea && !regions[i].connectsToBorder)
+		{
+			unsigned short reg = regions[i].id;
+			for (int j = 0; j < nreg; ++j)
+				if (regions[j].id == reg)
+					regions[j].id = 0;
+		}
+	}
+	
+	// Compress region Ids.
+	for (int i = 0; i < nreg; ++i)
+	{
+		regions[i].remap = false;
+		if (regions[i].id == 0) continue;				// Skip nil regions.
+		if (regions[i].id & RC_BORDER_REG) continue;    // Skip external regions.
+		regions[i].remap = true;
+	}
+	
+	unsigned short regIdGen = 0;
+	for (int i = 0; i < nreg; ++i)
+	{
+		if (!regions[i].remap)
+			continue;
+		unsigned short oldId = regions[i].id;
+		unsigned short newId = ++regIdGen;
+		for (int j = i; j < nreg; ++j)
+		{
+			if (regions[j].id == oldId)
+			{
+				regions[j].id = newId;
+				regions[j].remap = false;
+			}
+		}
+	}
+	maxRegionId = regIdGen;
+	
+	// Remap regions.
+	for (int i = 0; i < chf.spanCount; ++i)
+	{
+		if ((srcReg[i] & RC_BORDER_REG) == 0)
+			srcReg[i] = regions[srcReg[i]].id;
+	}
 	
 	for (int i = 0; i < nreg; ++i)
 		regions[i].~rcRegion();
@@ -936,6 +1241,8 @@ static bool filterSmallRegions(rcContext* ctx, int minRegionArea, int mergeRegio
 	return true;
 }
 
+
+
 /// @par
 /// 
 /// This is usually the second to the last step in creating a fully built
@@ -950,7 +1257,7 @@ bool rcBuildDistanceField(rcContext* ctx, rcCompactHeightfield& chf)
 {
 	rcAssert(ctx);
 	
-	ctx->startTimer(RC_TIMER_BUILD_DISTANCEFIELD);
+	rcScopedTimer timer(ctx, RC_TIMER_BUILD_DISTANCEFIELD);
 	
 	if (chf.dist)
 	{
@@ -974,25 +1281,23 @@ bool rcBuildDistanceField(rcContext* ctx, rcCompactHeightfield& chf)
 	
 	unsigned short maxDist = 0;
 
-	ctx->startTimer(RC_TIMER_BUILD_DISTANCEFIELD_DIST);
-	
-	calculateDistanceField(chf, src, maxDist);
-	chf.maxDistance = maxDist;
-	
-	ctx->stopTimer(RC_TIMER_BUILD_DISTANCEFIELD_DIST);
-	
-	ctx->startTimer(RC_TIMER_BUILD_DISTANCEFIELD_BLUR);
-	
-	// Blur
-	if (boxBlur(chf, 1, src, dst) != src)
-		rcSwap(src, dst);
-	
-	// Store distance.
-	chf.dist = src;
-	
-	ctx->stopTimer(RC_TIMER_BUILD_DISTANCEFIELD_BLUR);
+	{
+		rcScopedTimer timerDist(ctx, RC_TIMER_BUILD_DISTANCEFIELD_DIST);
 
-	ctx->stopTimer(RC_TIMER_BUILD_DISTANCEFIELD);
+		calculateDistanceField(chf, src, maxDist);
+		chf.maxDistance = maxDist;
+	}
+
+	{
+		rcScopedTimer timerBlur(ctx, RC_TIMER_BUILD_DISTANCEFIELD_BLUR);
+
+		// Blur
+		if (boxBlur(chf, 1, src, dst) != src)
+			rcSwap(src, dst);
+
+		// Store distance.
+		chf.dist = src;
+	}
 	
 	rcFree(dst);
 	
@@ -1052,13 +1357,13 @@ bool rcBuildRegionsMonotone(rcContext* ctx, rcCompactHeightfield& chf,
 {
 	rcAssert(ctx);
 	
-	ctx->startTimer(RC_TIMER_BUILD_REGIONS);
+	rcScopedTimer timer(ctx, RC_TIMER_BUILD_REGIONS);
 	
 	const int w = chf.width;
 	const int h = chf.height;
 	unsigned short id = 1;
 	
-	rcScopedDelete<unsigned short> srcReg = (unsigned short*)rcAlloc(sizeof(unsigned short)*chf.spanCount, RC_ALLOC_TEMP);
+	rcScopedDelete<unsigned short> srcReg((unsigned short*)rcAlloc(sizeof(unsigned short)*chf.spanCount, RC_ALLOC_TEMP));
 	if (!srcReg)
 	{
 		ctx->log(RC_LOG_ERROR, "rcBuildRegionsMonotone: Out of memory 'src' (%d).", chf.spanCount);
@@ -1067,7 +1372,7 @@ bool rcBuildRegionsMonotone(rcContext* ctx, rcCompactHeightfield& chf,
 	memset(srcReg,0,sizeof(unsigned short)*chf.spanCount);
 
 	const int nsweeps = rcMax(chf.width,chf.height);
-	rcScopedDelete<rcSweepSpan> sweeps = (rcSweepSpan*)rcAlloc(sizeof(rcSweepSpan)*nsweeps, RC_ALLOC_TEMP);
+	rcScopedDelete<rcSweepSpan> sweeps((rcSweepSpan*)rcAlloc(sizeof(rcSweepSpan)*nsweeps, RC_ALLOC_TEMP));
 	if (!sweeps)
 	{
 		ctx->log(RC_LOG_ERROR, "rcBuildRegionsMonotone: Out of memory 'sweeps' (%d).", nsweeps);
@@ -1181,20 +1486,22 @@ bool rcBuildRegionsMonotone(rcContext* ctx, rcCompactHeightfield& chf,
 		}
 	}
 
-	ctx->startTimer(RC_TIMER_BUILD_REGIONS_FILTER);
 
-	// Filter out small regions.
-	chf.maxRegions = id;
-	if (!filterSmallRegions(ctx, minRegionArea, mergeRegionArea, chf.maxRegions, chf, srcReg))
-		return false;
+	{
+		rcScopedTimer timerFilter(ctx, RC_TIMER_BUILD_REGIONS_FILTER);
 
-	ctx->stopTimer(RC_TIMER_BUILD_REGIONS_FILTER);
+		// Merge regions and filter out small regions.
+		rcIntArray overlaps;
+		chf.maxRegions = id;
+		if (!mergeAndFilterRegions(ctx, minRegionArea, mergeRegionArea, chf.maxRegions, chf, srcReg, overlaps))
+			return false;
+
+		// Monotone partitioning does not generate overlapping regions.
+	}
 	
 	// Store the result out.
 	for (int i = 0; i < chf.spanCount; ++i)
 		chf.spans[i].reg = srcReg[i];
-	
-	ctx->stopTimer(RC_TIMER_BUILD_REGIONS);
 
 	return true;
 }
@@ -1223,12 +1530,12 @@ bool rcBuildRegions(rcContext* ctx, rcCompactHeightfield& chf,
 {
 	rcAssert(ctx);
 	
-	ctx->startTimer(RC_TIMER_BUILD_REGIONS);
+	rcScopedTimer timer(ctx, RC_TIMER_BUILD_REGIONS);
 	
 	const int w = chf.width;
 	const int h = chf.height;
 	
-	rcScopedDelete<unsigned short> buf = (unsigned short*)rcAlloc(sizeof(unsigned short)*chf.spanCount*4, RC_ALLOC_TEMP);
+	rcScopedDelete<unsigned short> buf((unsigned short*)rcAlloc(sizeof(unsigned short)*chf.spanCount*4, RC_ALLOC_TEMP));
 	if (!buf)
 	{
 		ctx->log(RC_LOG_ERROR, "rcBuildRegions: Out of memory 'tmp' (%d).", chf.spanCount*4);
@@ -1236,7 +1543,13 @@ bool rcBuildRegions(rcContext* ctx, rcCompactHeightfield& chf,
 	}
 	
 	ctx->startTimer(RC_TIMER_BUILD_REGIONS_WATERSHED);
-	
+
+	const int LOG_NB_STACKS = 3;
+	const int NB_STACKS = 1 << LOG_NB_STACKS;
+	rcIntArray lvlStacks[NB_STACKS];
+	for (int i=0; i<NB_STACKS; ++i)
+		lvlStacks[i].resize(1024);
+
 	rcIntArray stack(1024);
 	rcIntArray visited(1024);
 	
@@ -1262,6 +1575,13 @@ bool rcBuildRegions(rcContext* ctx, rcCompactHeightfield& chf,
 		// Make sure border will not overflow.
 		const int bw = rcMin(w, borderSize);
 		const int bh = rcMin(h, borderSize);
+
+		if (regionId > 0xFFFB)
+		{
+			ctx->log(RC_LOG_ERROR, "rcBuildRegions: Region ID overflow");
+			return false;
+		}
+		
 		// Paint regions
 		paintRectRegion(0, bw, 0, h, regionId|RC_BORDER_REG, chf, srcReg); regionId++;
 		paintRectRegion(w-bw, w, 0, h, regionId|RC_BORDER_REG, chf, srcReg); regionId++;
@@ -1271,44 +1591,60 @@ bool rcBuildRegions(rcContext* ctx, rcCompactHeightfield& chf,
 		chf.borderSize = borderSize;
 	}
 	
+	int sId = -1;
 	while (level > 0)
 	{
 		level = level >= 2 ? level-2 : 0;
-		
-		ctx->startTimer(RC_TIMER_BUILD_REGIONS_EXPAND);
-		
-		// Expand current regions until no empty connected cells found.
-		if (expandRegions(expandIters, level, chf, srcReg, srcDist, dstReg, dstDist, stack) != srcReg)
+		sId = (sId+1) & (NB_STACKS-1);
+
+//		ctx->startTimer(RC_TIMER_DIVIDE_TO_LEVELS);
+
+		if (sId == 0)
+			sortCellsByLevel(level, chf, srcReg, NB_STACKS, lvlStacks, 1);
+		else 
+			appendStacks(lvlStacks[sId-1], lvlStacks[sId], srcReg); // copy left overs from last level
+
+//		ctx->stopTimer(RC_TIMER_DIVIDE_TO_LEVELS);
+
 		{
-			rcSwap(srcReg, dstReg);
-			rcSwap(srcDist, dstDist);
+			rcScopedTimer timerExpand(ctx, RC_TIMER_BUILD_REGIONS_EXPAND);
+
+			// Expand current regions until no empty connected cells found.
+			if (expandRegions(expandIters, level, chf, srcReg, srcDist, dstReg, dstDist, lvlStacks[sId], false) != srcReg)
+			{
+				rcSwap(srcReg, dstReg);
+				rcSwap(srcDist, dstDist);
+			}
 		}
 		
-		ctx->stopTimer(RC_TIMER_BUILD_REGIONS_EXPAND);
-		
-		ctx->startTimer(RC_TIMER_BUILD_REGIONS_FLOOD);
-		
-		// Mark new regions with IDs.
-		for (int y = 0; y < h; ++y)
 		{
-			for (int x = 0; x < w; ++x)
+			rcScopedTimer timerFloor(ctx, RC_TIMER_BUILD_REGIONS_FLOOD);
+
+			// Mark new regions with IDs.
+			for (int j = 0; j<lvlStacks[sId].size(); j += 3)
 			{
-				const rcCompactCell& c = chf.cells[x+y*w];
-				for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i)
+				int x = lvlStacks[sId][j];
+				int y = lvlStacks[sId][j+1];
+				int i = lvlStacks[sId][j+2];
+				if (i >= 0 && srcReg[i] == 0)
 				{
-					if (chf.dist[i] < level || srcReg[i] != 0 || chf.areas[i] == RC_NULL_AREA)
-						continue;
 					if (floodRegion(x, y, i, level, regionId, chf, srcReg, srcDist, stack))
+					{
+						if (regionId == 0xFFFF)
+						{
+							ctx->log(RC_LOG_ERROR, "rcBuildRegions: Region ID overflow");
+							return false;
+						}
+						
 						regionId++;
+					}
 				}
 			}
 		}
-		
-		ctx->stopTimer(RC_TIMER_BUILD_REGIONS_FLOOD);
 	}
 	
 	// Expand current regions until no empty connected cells found.
-	if (expandRegions(expandIters*8, 0, chf, srcReg, srcDist, dstReg, dstDist, stack) != srcReg)
+	if (expandRegions(expandIters*8, 0, chf, srcReg, srcDist, dstReg, dstDist, stack, true) != srcReg)
 	{
 		rcSwap(srcReg, dstReg);
 		rcSwap(srcDist, dstDist);
@@ -1316,22 +1652,179 @@ bool rcBuildRegions(rcContext* ctx, rcCompactHeightfield& chf,
 	
 	ctx->stopTimer(RC_TIMER_BUILD_REGIONS_WATERSHED);
 	
-	ctx->startTimer(RC_TIMER_BUILD_REGIONS_FILTER);
-	
-	// Filter out small regions.
-	chf.maxRegions = regionId;
-	if (!filterSmallRegions(ctx, minRegionArea, mergeRegionArea, chf.maxRegions, chf, srcReg))
-		return false;
-	
-	ctx->stopTimer(RC_TIMER_BUILD_REGIONS_FILTER);
+	{
+		rcScopedTimer timerFilter(ctx, RC_TIMER_BUILD_REGIONS_FILTER);
+
+		// Merge regions and filter out smalle regions.
+		rcIntArray overlaps;
+		chf.maxRegions = regionId;
+		if (!mergeAndFilterRegions(ctx, minRegionArea, mergeRegionArea, chf.maxRegions, chf, srcReg, overlaps))
+			return false;
+
+		// If overlapping regions were found during merging, split those regions.
+		if (overlaps.size() > 0)
+		{
+			ctx->log(RC_LOG_ERROR, "rcBuildRegions: %d overlapping regions.", overlaps.size());
+		}
+	}
 		
 	// Write the result out.
 	for (int i = 0; i < chf.spanCount; ++i)
 		chf.spans[i].reg = srcReg[i];
 	
-	ctx->stopTimer(RC_TIMER_BUILD_REGIONS);
-	
 	return true;
 }
 
 
+bool rcBuildLayerRegions(rcContext* ctx, rcCompactHeightfield& chf,
+						 const int borderSize, const int minRegionArea)
+{
+	rcAssert(ctx);
+	
+	rcScopedTimer timer(ctx, RC_TIMER_BUILD_REGIONS);
+	
+	const int w = chf.width;
+	const int h = chf.height;
+	unsigned short id = 1;
+	
+	rcScopedDelete<unsigned short> srcReg((unsigned short*)rcAlloc(sizeof(unsigned short)*chf.spanCount, RC_ALLOC_TEMP));
+	if (!srcReg)
+	{
+		ctx->log(RC_LOG_ERROR, "rcBuildRegionsMonotone: Out of memory 'src' (%d).", chf.spanCount);
+		return false;
+	}
+	memset(srcReg,0,sizeof(unsigned short)*chf.spanCount);
+	
+	const int nsweeps = rcMax(chf.width,chf.height);
+	rcScopedDelete<rcSweepSpan> sweeps((rcSweepSpan*)rcAlloc(sizeof(rcSweepSpan)*nsweeps, RC_ALLOC_TEMP));
+	if (!sweeps)
+	{
+		ctx->log(RC_LOG_ERROR, "rcBuildRegionsMonotone: Out of memory 'sweeps' (%d).", nsweeps);
+		return false;
+	}
+	
+	
+	// Mark border regions.
+	if (borderSize > 0)
+	{
+		// Make sure border will not overflow.
+		const int bw = rcMin(w, borderSize);
+		const int bh = rcMin(h, borderSize);
+		// Paint regions
+		paintRectRegion(0, bw, 0, h, id|RC_BORDER_REG, chf, srcReg); id++;
+		paintRectRegion(w-bw, w, 0, h, id|RC_BORDER_REG, chf, srcReg); id++;
+		paintRectRegion(0, w, 0, bh, id|RC_BORDER_REG, chf, srcReg); id++;
+		paintRectRegion(0, w, h-bh, h, id|RC_BORDER_REG, chf, srcReg); id++;
+		
+		chf.borderSize = borderSize;
+	}
+	
+	rcIntArray prev(256);
+	
+	// Sweep one line at a time.
+	for (int y = borderSize; y < h-borderSize; ++y)
+	{
+		// Collect spans from this row.
+		prev.resize(id+1);
+		memset(&prev[0],0,sizeof(int)*id);
+		unsigned short rid = 1;
+		
+		for (int x = borderSize; x < w-borderSize; ++x)
+		{
+			const rcCompactCell& c = chf.cells[x+y*w];
+			
+			for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i)
+			{
+				const rcCompactSpan& s = chf.spans[i];
+				if (chf.areas[i] == RC_NULL_AREA) continue;
+				
+				// -x
+				unsigned short previd = 0;
+				if (rcGetCon(s, 0) != RC_NOT_CONNECTED)
+				{
+					const int ax = x + rcGetDirOffsetX(0);
+					const int ay = y + rcGetDirOffsetY(0);
+					const int ai = (int)chf.cells[ax+ay*w].index + rcGetCon(s, 0);
+					if ((srcReg[ai] & RC_BORDER_REG) == 0 && chf.areas[i] == chf.areas[ai])
+						previd = srcReg[ai];
+				}
+				
+				if (!previd)
+				{
+					previd = rid++;
+					sweeps[previd].rid = previd;
+					sweeps[previd].ns = 0;
+					sweeps[previd].nei = 0;
+				}
+				
+				// -y
+				if (rcGetCon(s,3) != RC_NOT_CONNECTED)
+				{
+					const int ax = x + rcGetDirOffsetX(3);
+					const int ay = y + rcGetDirOffsetY(3);
+					const int ai = (int)chf.cells[ax+ay*w].index + rcGetCon(s, 3);
+					if (srcReg[ai] && (srcReg[ai] & RC_BORDER_REG) == 0 && chf.areas[i] == chf.areas[ai])
+					{
+						unsigned short nr = srcReg[ai];
+						if (!sweeps[previd].nei || sweeps[previd].nei == nr)
+						{
+							sweeps[previd].nei = nr;
+							sweeps[previd].ns++;
+							prev[nr]++;
+						}
+						else
+						{
+							sweeps[previd].nei = RC_NULL_NEI;
+						}
+					}
+				}
+				
+				srcReg[i] = previd;
+			}
+		}
+		
+		// Create unique ID.
+		for (int i = 1; i < rid; ++i)
+		{
+			if (sweeps[i].nei != RC_NULL_NEI && sweeps[i].nei != 0 &&
+				prev[sweeps[i].nei] == (int)sweeps[i].ns)
+			{
+				sweeps[i].id = sweeps[i].nei;
+			}
+			else
+			{
+				sweeps[i].id = id++;
+			}
+		}
+		
+		// Remap IDs
+		for (int x = borderSize; x < w-borderSize; ++x)
+		{
+			const rcCompactCell& c = chf.cells[x+y*w];
+			
+			for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i)
+			{
+				if (srcReg[i] > 0 && srcReg[i] < rid)
+					srcReg[i] = sweeps[srcReg[i]].id;
+			}
+		}
+	}
+	
+	
+	{
+		rcScopedTimer timerFilter(ctx, RC_TIMER_BUILD_REGIONS_FILTER);
+
+		// Merge monotone regions to layers and remove small regions.
+		rcIntArray overlaps;
+		chf.maxRegions = id;
+		if (!mergeAndFilterLayerRegions(ctx, minRegionArea, chf.maxRegions, chf, srcReg, overlaps))
+			return false;
+	}
+	
+	
+	// Store the result out.
+	for (int i = 0; i < chf.spanCount; ++i)
+		chf.spans[i].reg = srcReg[i];
+	
+	return true;
+}