Added a thickness parameter to //hollow.

src/main/java/com/sk89q/worldedit/EditSession.java

@@ -2731,7 +2731,7 @@ public class EditSession {
      * @return number of blocks affected
      * @throws MaxChangedBlocksException
      */
-    public int hollowOutRegion(Region region) throws MaxChangedBlocksException {
+    public int hollowOutRegion(Region region, int thickness) throws MaxChangedBlocksException {
         int affected = 0;
 
         Set<BlockVector> outside = new HashSet<BlockVector>();
@@ -2769,6 +2769,23 @@ public class EditSession {
 
         BaseBlock air = new BaseBlock(BlockID.AIR);
 
+
+        for (int i = 1; i < thickness; ++i) {
+            final Set<BlockVector> newOutside = new HashSet<BlockVector>(outside);
+            outer: for (BlockVector position : region) {
+                for (Vector recurseDirection: recurseDirections) {
+                    BlockVector neighbor = position.add(recurseDirection).toBlockVector();
+
+                    if (outside.contains(neighbor)) {
+                        newOutside.add(position);
+                        continue outer;
+                    }
+                }
+            }
+
+            outside = newOutside;
+        }
+
         outer: for (BlockVector position : region) {
             for (Vector recurseDirection: recurseDirections) {
                 BlockVector neighbor = position.add(recurseDirection).toBlockVector();

src/main/java/com/sk89q/worldedit/commands/RegionCommands.java

@@ -394,17 +394,19 @@ public class RegionCommands {
 
     @Command(
         aliases = { "/hollow" },
-        usage = "",
+        usage = "[<thickness>]",
         desc = "Hollows out the object contained in this selection",
         min = 0,
-        max = 0
+        max = 1
     )
     @CommandPermissions("worldedit.region.hollow")
     @Logging(REGION)
     public void hollow(CommandContext args, LocalSession session, LocalPlayer player,
             EditSession editSession) throws WorldEditException {
 
-        int affected = editSession.hollowOutRegion(session.getSelection(player.getWorld()));
+        int thickness = args.argsLength() > 0 ? Math.max(1, args.getInteger(0)) : 1;
+
+        int affected = editSession.hollowOutRegion(session.getSelection(player.getWorld()), thickness);
 
         player.print(affected + " block(s) have been changed.");
     }