diff --git a/Recast/Include/Recast.h b/Recast/Include/Recast.h
index dc762a1..9def8fd 100644
--- a/Recast/Include/Recast.h
+++ b/Recast/Include/Recast.h
@@ -1083,7 +1083,7 @@ int rcGetHeightFieldSpanCount(rcContext* context, const rcHeightfield& heightfie
 /// @param[out]		compactHeightfield	The resulting compact heightfield. (Must be pre-allocated.)
 /// @returns True if the operation completed successfully.
 bool rcBuildCompactHeightfield(rcContext* context, int walkableHeight, int walkableClimb,
-							   rcHeightfield& heightfield, rcCompactHeightfield& compactHeightfield);
+							   const rcHeightfield& heightfield, rcCompactHeightfield& compactHeightfield);
 
 /// Erodes the walkable area within the heightfield by the specified radius. 
 /// @ingroup recast
@@ -1256,7 +1256,7 @@ inline int rcGetDirForOffset(int offsetX, int offsetZ)
 ///  								to be considered walkable. [Limit: >= 3] [Units: vx]
 /// @param[out]		lset			The resulting layer set. (Must be pre-allocated.)
 /// @returns True if the operation completed successfully.
-bool rcBuildHeightfieldLayers(rcContext* ctx, rcCompactHeightfield& chf, 
+bool rcBuildHeightfieldLayers(rcContext* ctx, const rcCompactHeightfield& chf, 
 							  int borderSize, int walkableHeight,
 							  rcHeightfieldLayerSet& lset);
 
@@ -1271,7 +1271,7 @@ bool rcBuildHeightfieldLayers(rcContext* ctx, rcCompactHeightfield& chf,
 /// @param[out]		cset		The resulting contour set. (Must be pre-allocated.)
 /// @param[in]		buildFlags	The build flags. (See: #rcBuildContoursFlags)
 /// @returns True if the operation completed successfully.
-bool rcBuildContours(rcContext* ctx, rcCompactHeightfield& chf,
+bool rcBuildContours(rcContext* ctx, const rcCompactHeightfield& chf,
 					 float maxError, int maxEdgeLen,
 					 rcContourSet& cset, int buildFlags = RC_CONTOUR_TESS_WALL_EDGES);
 
@@ -1283,7 +1283,7 @@ bool rcBuildContours(rcContext* ctx, rcCompactHeightfield& chf,
 /// 						contour to polygon conversion process. [Limit: >= 3] 
 /// @param[out]		mesh	The resulting polygon mesh. (Must be re-allocated.)
 /// @returns True if the operation completed successfully.
-bool rcBuildPolyMesh(rcContext* ctx, rcContourSet& cset, const int nvp, rcPolyMesh& mesh);
+bool rcBuildPolyMesh(rcContext* ctx, const rcContourSet& cset, const int nvp, rcPolyMesh& mesh);
 
 /// Merges multiple polygon meshes into a single mesh.
 ///  @ingroup recast
diff --git a/Recast/Source/Recast.cpp b/Recast/Source/Recast.cpp
index 073e595..d75a9f5 100644
--- a/Recast/Source/Recast.cpp
+++ b/Recast/Source/Recast.cpp
@@ -401,7 +401,7 @@ int rcGetHeightFieldSpanCount(rcContext* context, const rcHeightfield& heightfie
 }
 
 bool rcBuildCompactHeightfield(rcContext* context, const int walkableHeight, const int walkableClimb,
-                               rcHeightfield& heightfield, rcCompactHeightfield& compactHeightfield)
+                               const rcHeightfield& heightfield, rcCompactHeightfield& compactHeightfield)
 {
 	rcAssert(context);
 
diff --git a/Recast/Source/RecastContour.cpp b/Recast/Source/RecastContour.cpp
index 4de5288..5508a98 100644
--- a/Recast/Source/RecastContour.cpp
+++ b/Recast/Source/RecastContour.cpp
@@ -101,7 +101,7 @@ static int getCornerHeight(int x, int y, int i, int dir,
 }
 
 static void walkContour(int x, int y, int i,
-						rcCompactHeightfield& chf,
+						const rcCompactHeightfield& chf,
 						unsigned char* flags, rcIntArray& points)
 {
 	// Choose the first non-connected edge
@@ -820,7 +820,7 @@ static void mergeRegionHoles(rcContext* ctx, rcContourRegion& region)
 /// See the #rcConfig documentation for more information on the configuration parameters.
 ///
 /// @see rcAllocContourSet, rcCompactHeightfield, rcContourSet, rcConfig
-bool rcBuildContours(rcContext* ctx, rcCompactHeightfield& chf,
+bool rcBuildContours(rcContext* ctx, const rcCompactHeightfield& chf,
 					 const float maxError, const int maxEdgeLen,
 					 rcContourSet& cset, const int buildFlags)
 {
diff --git a/Recast/Source/RecastLayers.cpp b/Recast/Source/RecastLayers.cpp
index 4d4fa46..ca37ebb 100644
--- a/Recast/Source/RecastLayers.cpp
+++ b/Recast/Source/RecastLayers.cpp
@@ -101,7 +101,7 @@ struct rcLayerSweepSpan
 /// See the #rcConfig documentation for more information on the configuration parameters.
 /// 
 /// @see rcAllocHeightfieldLayerSet, rcCompactHeightfield, rcHeightfieldLayerSet, rcConfig
-bool rcBuildHeightfieldLayers(rcContext* ctx, rcCompactHeightfield& chf,
+bool rcBuildHeightfieldLayers(rcContext* ctx, const rcCompactHeightfield& chf,
 							  const int borderSize, const int walkableHeight,
 							  rcHeightfieldLayerSet& lset)
 {
diff --git a/Recast/Source/RecastMesh.cpp b/Recast/Source/RecastMesh.cpp
index 9bffd6d..3b682df 100644
--- a/Recast/Source/RecastMesh.cpp
+++ b/Recast/Source/RecastMesh.cpp
@@ -986,7 +986,7 @@ static bool removeVertex(rcContext* ctx, rcPolyMesh& mesh, const unsigned short
 /// limit must be retricted to <= #DT_VERTS_PER_POLYGON.
 ///
 /// @see rcAllocPolyMesh, rcContourSet, rcPolyMesh, rcConfig
-bool rcBuildPolyMesh(rcContext* ctx, rcContourSet& cset, const int nvp, rcPolyMesh& mesh)
+bool rcBuildPolyMesh(rcContext* ctx, const rcContourSet& cset, const int nvp, rcPolyMesh& mesh)
 {
 	rcAssert(ctx);