Rewrote surface grouping method to be iterative instead of tail-recursive. Fixes potential stack overflow issues when loading particularly large and complex maps.

Assets/Scripts/Support/BrushModel.cs

@@ -66,8 +66,14 @@ public class BrushModel
 
     private void GroupSurfaces(QNode node, QSurface[] surfaces, Dictionary<(IntPtr, int, QSurfaceFlags), List<QSurface>> surfaceGroups)
     {
+        var nodeQueue = new Queue<QNode>();
+        nodeQueue.Enqueue(node);
+
+        while (nodeQueue.Count > 0)
+        {
+            node = nodeQueue.Dequeue();
             if (node.contents < 0)  // Leaf node
-            return;
+                continue;
             
             for (int surfIdx = 0; surfIdx < node.numSurfaces; ++surfIdx)
             {
@@ -86,7 +92,8 @@ public class BrushModel
 
             foreach (var childNode in node.Children)
             {
-            GroupSurfaces(childNode, surfaces, surfaceGroups);
+                nodeQueue.Enqueue(childNode);
+            }
         }
     }