Changed to use Span<byte> and stackalloc for improved performance and memory management in `RcLayers.BuildHeightfieldLayers()`

CHANGELOG.md

@@ -18,7 +18,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Changed `reg`, `area` arrays to byte arrays for uniformity and efficiency in `DtTileCacheContour`
 - Changed `RcChunkyTriMesh` to separate the function and variable.
 - Changed to consolidate vector-related functions into one place.
-- Changed stack handling from List to a fixed-size array with manual index management for optimization in `RcLayers.BuildHeightfieldLayers`
+- Changed stack handling from List to a fixed-size array with manual index management for optimization in `RcLayers.BuildHeightfieldLayers()`
+- Changed to use Span<byte> and stackalloc for improved performance and memory management in `RcLayers.BuildHeightfieldLayers()`
 
 ### Removed
 - Removed RcMeshDetails.VdistSq2(float[], float[])

src/DotRecast.Recast/RcLayers.cs

@@ -25,7 +25,6 @@ using DotRecast.Core.Numerics;
 
 namespace DotRecast.Recast
 {
-    
     using static RcRecast;
 
     public static class RcLayers
@@ -61,7 +60,6 @@ namespace DotRecast.Recast
         /// @name Layer, Contour, Polymesh, and Detail Mesh Functions
         /// @see rcHeightfieldLayer, rcContourSet, rcPolyMesh, rcPolyMeshDetail
         /// @{
-
         /// Builds a layer set from the specified compact heightfield.
         /// @ingroup recast
         /// @param[in,out]	ctx				The build context to use during the operation.
@@ -80,8 +78,8 @@ namespace DotRecast.Recast
             int w = chf.width;
             int h = chf.height;
 
-            byte[] srcReg = new byte[chf.spanCount];
-            Array.Fill(srcReg, (byte)0xFF);
+            Span<byte> srcReg = stackalloc byte[chf.spanCount];
+            srcReg.Fill(0xFF);
 
             int nsweeps = chf.width;
             RcLayerSweepSpan[] sweeps = new RcLayerSweepSpan[nsweeps];
@@ -91,14 +89,14 @@ namespace DotRecast.Recast
             }
 
             // Partition walkable area into monotone regions.
-            int[] prevCount = new int[256];
+            Span<int> prevCount = stackalloc int[256];
             byte regId = 0;
 
             // Sweep one line at a time.
             for (int y = borderSize; y < h - borderSize; ++y)
             {
                 // Collect spans from this row.
-                Array.Fill(prevCount, 0);
+                prevCount.Fill(0);
                 byte sweepId = 0;
 
                 for (int x = borderSize; x < w - borderSize; ++x)