diff --git a/src/DotRecast.Recast.Toolset/Builder/SampleAreaModifications.cs b/src/DotRecast.Recast.Toolset/Builder/SampleAreaModifications.cs
index 1ed8bc7..367698c 100644
--- a/src/DotRecast.Recast.Toolset/Builder/SampleAreaModifications.cs
+++ b/src/DotRecast.Recast.Toolset/Builder/SampleAreaModifications.cs
@@ -61,9 +61,9 @@ namespace DotRecast.Recast.Toolset.Builder
 
         public static RcAreaModification OfValue(int value)
         {
-            foreach(var v in Values)
+            foreach (var v in Values)
             {
-                if(v.Value == value)
+                if (v.Value == value)
                 {
                     return v;
                 }
diff --git a/src/DotRecast.Recast/RcCommons.cs b/src/DotRecast.Recast/RcCommons.cs
index 1cb3373..93ba642 100644
--- a/src/DotRecast.Recast/RcCommons.cs
+++ b/src/DotRecast.Recast/RcCommons.cs
@@ -36,7 +36,7 @@ namespace DotRecast.Recast
         /// @param[in]		span			The span to update.
         /// @param[in]		direction		The direction to set. [Limits: 0 <= value < 4]
         /// @param[in]		neighborIndex	The index of the neighbor span.
-        public static void SetCon(ref RcCompactSpan span, int direction, int neighborIndex)
+        public static void SetCon(RcCompactSpan span, int direction, int neighborIndex)
         {
             int shift = direction * 6;
             int con = span.con;
diff --git a/src/DotRecast.Recast/RcCompactSpan.cs b/src/DotRecast.Recast/RcCompactSpan.cs
index 066ab8e..de1e55d 100644
--- a/src/DotRecast.Recast/RcCompactSpan.cs
+++ b/src/DotRecast.Recast/RcCompactSpan.cs
@@ -21,7 +21,7 @@ freely, subject to the following restrictions:
 namespace DotRecast.Recast
 {
     /** Represents a span of unobstructed space within a compact heightfield. */
-    public struct RcCompactSpan
+    public class RcCompactSpan
     {
         /** The lower extent of the span. (Measured from the heightfield's base.) */
         public int y;
diff --git a/src/DotRecast.Recast/RcCompacts.cs b/src/DotRecast.Recast/RcCompacts.cs
index a1cfc82..d53eae0 100644
--- a/src/DotRecast.Recast/RcCompacts.cs
+++ b/src/DotRecast.Recast/RcCompacts.cs
@@ -115,11 +115,11 @@ namespace DotRecast.Recast
                     RcCompactCell c = chf.cells[x + y * w];
                     for (int i = c.index, ni = c.index + c.count; i < ni; ++i)
                     {
-                        ref RcCompactSpan s = ref chf.spans[i];
+                        RcCompactSpan s = chf.spans[i];
 
                         for (int dir = 0; dir < 4; ++dir)
                         {
-                            SetCon(ref s, dir, RC_NOT_CONNECTED);
+                            SetCon(s, dir, RC_NOT_CONNECTED);
                             int nx = x + GetDirOffsetX(dir);
                             int ny = y + GetDirOffsetY(dir);
                             // First check that the neighbour cell is in bounds.
@@ -131,7 +131,7 @@ namespace DotRecast.Recast
                             RcCompactCell nc = chf.cells[nx + ny * w];
                             for (int k = nc.index, nk = nc.index + nc.count; k < nk; ++k)
                             {
-                                ref RcCompactSpan ns = ref chf.spans[k];
+                                RcCompactSpan ns = chf.spans[k];
                                 int bot = Math.Max(s.y, ns.y);
                                 int top = Math.Min(s.y + s.h, ns.y + ns.h);
 
@@ -147,7 +147,7 @@ namespace DotRecast.Recast
                                         continue;
                                     }
 
-                                    SetCon(ref s, dir, lidx);
+                                    SetCon(s, dir, lidx);
                                     break;
                                 }
                             }
diff --git a/src/DotRecast.Recast/RcLayers.cs b/src/DotRecast.Recast/RcLayers.cs
index 6ffd8d5..1073794 100644
--- a/src/DotRecast.Recast/RcLayers.cs
+++ b/src/DotRecast.Recast/RcLayers.cs
@@ -30,6 +30,10 @@ namespace DotRecast.Recast
 
     public static class RcLayers
     {
+        const int RC_MAX_LAYERS = RcConstants.RC_NOT_CONNECTED;
+        const int RC_MAX_NEIS = 16;
+
+
         private static void AddUnique(List<int> a, int v)
         {
             if (!a.Contains(v))
@@ -59,6 +63,10 @@ namespace DotRecast.Recast
             Array.Fill(srcReg, 0xFF);
             int nsweeps = chf.width; // Math.Max(chf.width, chf.height);
             RcSweepSpan[] sweeps = new RcSweepSpan[nsweeps];
+            for (int i = 0; i < sweeps.Length; i++)
+            {
+                sweeps[i] = new RcSweepSpan();
+            }
 
             // Partition walkable area into monotone regions.
             int[] prevCount = new int[256];
@@ -297,7 +305,7 @@ namespace DotRecast.Recast
 
                 int newId = ri.layerId;
 
-                while (true)
+                for (;;)
                 {
                     int oldId = 0xff;
 
diff --git a/src/DotRecast.Recast/RcSweepSpan.cs b/src/DotRecast.Recast/RcSweepSpan.cs
index fcc87cb..4dcb80b 100644
--- a/src/DotRecast.Recast/RcSweepSpan.cs
+++ b/src/DotRecast.Recast/RcSweepSpan.cs
@@ -1,6 +1,6 @@
-namespace DotRecast.Recast
+namespace DotRecast.Recast
 {
-    public struct RcSweepSpan
+    public class RcSweepSpan
     {
         public int rid; // row id
         public int id; // region id