Add /center commmand

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

@@ -1352,6 +1352,27 @@ public class EditSession {
         return affected;
     }
 
+    public int center(Region region, Pattern pattern)
+            throws MaxChangedBlocksException {
+        Vector center = region.getCenter();
+        int x2 = center.getBlockX();
+        int y2 = center.getBlockY();
+        int z2 = center.getBlockZ();
+
+        int affected = 0;
+        for (int x = (int) center.getX(); x <= x2; x++) {
+            for (int y = (int) center.getY(); y <= y2; y++) {
+                for (int z = (int) center.getZ(); z <= z2; z++) {
+                    if (setBlock(new Vector(x, y, z), pattern)) {
+                        affected++;
+                    }
+                }
+            }
+        }
+
+        return affected;
+    }
+
     /**
      * Make faces of the region (as if it was a cuboid if it's not).
      *

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

@@ -144,6 +144,22 @@ public class RegionCommands {
         player.print(affected + " block(s) have been overlayed.");
     }
 
+    @Command(
+        aliases = { "/center", "/middle" },
+        usage = "<block>",
+        desc = "Set the center block(s)",
+        min = 1,
+        max = 1
+    )
+    public void center(CommandContext args, LocalSession session, LocalPlayer player,
+            EditSession editSession) throws WorldEditException {
+        Pattern pattern = we.getBlockPattern(player, args.getString(0));
+        Region region = session.getSelection(player.getWorld());
+
+        int affected = editSession.center(region, pattern);
+        player.print("Center set ("+ affected + " blocks changed)");
+    }
+
     @Command(
         aliases = { "/naturalize" },
         usage = "",

src/main/java/com/sk89q/worldedit/regions/AbstractRegion.java

@@ -35,6 +35,11 @@ public abstract class AbstractRegion implements Region {
         this.world = world;
     }
 
+    @Override
+    public Vector getCenter() {
+        return getMinimumPoint().add(getMaximumPoint()).divide(2);
+    }
+
     /**
      * Get the iterator.
      *

src/main/java/com/sk89q/worldedit/regions/CylinderRegion.java

@@ -87,6 +87,7 @@ public class CylinderRegion extends AbstractRegion implements FlatRegion {
      *
      * @return
      */
+    @Override
     public Vector getCenter() {
         return center.toVector((maxY + minY) / 2);
     }

src/main/java/com/sk89q/worldedit/regions/EllipsoidRegion.java

@@ -175,6 +175,7 @@ public class EllipsoidRegion extends AbstractRegion {
      *
      * @return center
      */
+    @Override
     public Vector getCenter() {
         return center;
     }

src/main/java/com/sk89q/worldedit/regions/Region.java

@@ -44,6 +44,15 @@ public interface Region extends Iterable<BlockVector>, Cloneable {
      */
     public Vector getMaximumPoint();
 
+    /**
+     * Get the center point of a region.
+     * Note: Coordinates will not be integers
+     * if the corresponding lengths are even.
+     *
+     * @return center point
+     */
+    public Vector getCenter();
+
     /**
      * Get the number of blocks in the region.
      *