Added new method to partition heighfield

- added layer based heighfield partitioning
- the method is a bit slower than monotone partitioning, but does not
suffer from the long thin ploys
- the method partitions the heighfield into non-overlapping areas, but
does not try to resolve holes
- improved contour hole merging so that it can properly handle all
kinds of holes
- improved polygon triangulation to handle overlapping segments
- improved small and long polygon detail mesh generation
- updated samples to include all 3 partition methods and little
documentation to help to choose between them

DebugUtils/Include/RecastDebugDraw.h

@@ -33,10 +33,6 @@ void duDebugDrawHeightfieldLayer(duDebugDraw* dd, const struct rcHeightfieldLaye
 void duDebugDrawHeightfieldLayers(duDebugDraw* dd, const struct rcHeightfieldLayerSet& lset);
 void duDebugDrawHeightfieldLayersRegions(duDebugDraw* dd, const struct rcHeightfieldLayerSet& lset);
 
-void duDebugDrawLayerContours(duDebugDraw* dd, const struct rcLayerContourSet& lcset);
-void duDebugDrawLayerPolyMesh(duDebugDraw* dd, const struct rcLayerPolyMesh& lmesh);
-
-
 void duDebugDrawRegionConnections(struct duDebugDraw* dd, const struct rcContourSet& cset, const float alpha = 1.0f);
 void duDebugDrawRawContours(struct duDebugDraw* dd, const struct rcContourSet& cset, const float alpha = 1.0f);
 void duDebugDrawContours(struct duDebugDraw* dd, const struct rcContourSet& cset, const float alpha = 1.0f);

Recast/Include/Recast.h

@@ -964,7 +964,7 @@ void rcMarkCylinderArea(rcContext* ctx, const float* pos,
 ///  @returns True if the operation completed successfully.
 bool rcBuildDistanceField(rcContext* ctx, rcCompactHeightfield& chf);
 
-/// Builds region data for the heightfield using watershed partitioning. 
+/// Builds region data for the heightfield using watershed partitioning.
 ///  @ingroup recast
 ///  @param[in,out]	ctx				The build context to use during the operation.
 ///  @param[in,out]	chf				A populated compact heightfield.
@@ -978,6 +978,18 @@ bool rcBuildDistanceField(rcContext* ctx, rcCompactHeightfield& chf);
 bool rcBuildRegions(rcContext* ctx, rcCompactHeightfield& chf,
 					const int borderSize, const int minRegionArea, const int mergeRegionArea);
 
+/// Builds region data for the heightfield by partitioning the heightfield in non-overlapping layers.
+///  @ingroup recast
+///  @param[in,out]	ctx				The build context to use during the operation.
+///  @param[in,out]	chf				A populated compact heightfield.
+///  @param[in]		borderSize		The size of the non-navigable border around the heightfield.
+///  								[Limit: >=0] [Units: vx]
+///  @param[in]		minRegionArea	The minimum number of cells allowed to form isolated island areas.
+///  								[Limit: >=0] [Units: vx].
+///  @returns True if the operation completed successfully.
+bool rcBuildLayerRegions(rcContext* ctx, rcCompactHeightfield& chf,
+						 const int borderSize, const int minRegionArea);
+
 /// Builds region data for the heightfield using simple monotone partitioning.
 ///  @ingroup recast 
 ///  @param[in,out]	ctx				The build context to use during the operation.
@@ -992,7 +1004,6 @@ bool rcBuildRegions(rcContext* ctx, rcCompactHeightfield& chf,
 bool rcBuildRegionsMonotone(rcContext* ctx, rcCompactHeightfield& chf,
 							const int borderSize, const int minRegionArea, const int mergeRegionArea);
 
-
 /// Sets the neighbor connection data for the specified direction.
 ///  @param[in]		s		The span to update.
 ///  @param[in]		dir		The direction to set. [Limits: 0 <= value < 4]