use moved RcRecast helpers

sources/engine/Stride.Navigation/NavigationBuilder.cs

@@ -96,7 +96,7 @@ public GeneratedData BuildNavmesh(ref Vector3[] vertices, ref int[] indices)
         }
 
         // Find walkable triangles and rasterize into heightfield
-        triAreas = MarkWalkableTriangles(context, buildSettings.AgentMaxSlope, verts, indices, numTriangles, new RcAreaModification(RcAreaModification.RC_AREA_FLAGS_MASK));
+        triAreas = RcRecast.MarkWalkableTriangles(context, buildSettings.AgentMaxSlope, verts, indices, numTriangles, new RcAreaModification(RcAreaModification.RC_AREA_FLAGS_MASK));
         RcRasterizations.RasterizeTriangles(context,  verts, indices, triAreas, numTriangles, solid, walkableClimb);
 
         // Filter walkable surfaces.
@@ -189,38 +189,4 @@ private bool CreateDetourMesh()
 
         return navmeshData != null;
     }
-
-    private static int[] MarkWalkableTriangles(RcContext ctx, float walkableSlopeAngle, float[] verts, int[] tris, int nt, RcAreaModification areaMod)
-    {
-        int[] array = new int[nt];
-        float num = MathF.Cos(walkableSlopeAngle / 180f * (float)Math.PI);
-        Vector3 norm = default(Vector3);
-        for (int i = 0; i < nt; i++)
-        {
-            int num2 = i * 3;
-            Vector3 v = ToVec3(verts, tris[num2] * 3);
-            Vector3 v2 = ToVec3(verts, tris[num2 + 1] * 3);
-            Vector3 v3 = ToVec3(verts, tris[num2 + 2] * 3);
-            CalcTriNormal(v, v2, v3, ref norm);
-            if (norm.Y > num)
-            {
-                array[i] = areaMod.Apply(array[i]);
-            }
-        }
-
-        return array;
-    }
-
-    private static void CalcTriNormal(Vector3 v0, Vector3 v1, Vector3 v2, ref Vector3 norm)
-    {
-        Vector3 v3 = v1 - v0;
-        Vector3 v4 = v2 - v0;
-        norm = Vector3.Cross(v3, v4);
-        norm = Vector3.Normalize(norm);
-    }
-
-    private static Vector3 ToVec3(float[] values, int n)
-    {
-        return new Vector3(values[n], values[n + 1], values[n + 2]);
-    }
 }