Added a gravity brush.

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

@@ -36,12 +36,7 @@ import com.sk89q.worldedit.masks.BlockTypeMask;
 import com.sk89q.worldedit.patterns.Pattern;
 import com.sk89q.worldedit.patterns.SingleBlockPattern;
 import com.sk89q.worldedit.tools.BrushTool;
-import com.sk89q.worldedit.tools.brushes.ClipboardBrush;
-import com.sk89q.worldedit.tools.brushes.CylinderBrush;
-import com.sk89q.worldedit.tools.brushes.HollowCylinderBrush;
-import com.sk89q.worldedit.tools.brushes.HollowSphereBrush;
-import com.sk89q.worldedit.tools.brushes.SmoothBrush;
-import com.sk89q.worldedit.tools.brushes.SphereBrush;
+import com.sk89q.worldedit.tools.brushes.*;
 
 /**
  * Brush shape commands.
@@ -244,4 +239,37 @@ public class BrushCommands {
         player.print(String.format("Extinguisher equipped (%.0f).",
                 radius));
     }
+
+    @Command(
+            aliases = { "gravity", "grav" },
+            usage = "[radius]",
+            flags = "h",
+            desc = "Gravity brush",
+            help =
+                "This brush simulates the affect of gravity.\n" +
+                "The -h flag makes it affect blocks starting at the world's max y, " +
+                    "instead of the clicked block's y + radius.",
+            min = 0,
+            max = 1
+    )
+    @CommandPermissions("worldedit.brush.gravity")
+    public void gravityBrush(CommandContext args, LocalSession session,
+                                LocalPlayer player, EditSession editSession) throws WorldEditException {
+
+        LocalConfiguration config = we.getConfiguration();
+
+        double radius = args.argsLength() > 0 ? args.getDouble(0) : 5;
+        if (radius > config.maxBrushRadius) {
+            player.printError("Maximum allowed brush radius: "
+                    + config.maxBrushRadius);
+            return;
+        }
+
+        BrushTool tool = session.getBrushTool(player.getItemInHand());
+        tool.setSize(radius);
+        tool.setBrush(new GravityBrush(args.hasFlag('h')), "worldedit.brush.gravity");
+
+        player.print(String.format("Gravity brush equipped (%.0f).",
+                radius));
+    }
 }

src/main/java/com/sk89q/worldedit/tools/brushes/GravityBrush.java

@@ -0,0 +1,67 @@
+/*
+ * WorldEdit
+ * Copyright (C) 2011 sk89q <http://www.sk89q.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.tools.brushes;
+
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.MaxChangedBlocksException;
+import com.sk89q.worldedit.Vector;
+import com.sk89q.worldedit.blocks.BaseBlock;
+import com.sk89q.worldedit.blocks.BlockID;
+import com.sk89q.worldedit.patterns.Pattern;
+
+import java.util.*;
+
+/**
+ * @author zml2008
+ */
+public class GravityBrush implements Brush {
+    private final boolean fullHeight;
+    
+    public GravityBrush(boolean fullHeight) {
+        this.fullHeight = fullHeight;
+    }
+
+    @Override
+    public void build(EditSession editSession, Vector pos, Pattern mat, double size) throws MaxChangedBlocksException {
+        final BaseBlock air = new BaseBlock(BlockID.AIR, 0);
+        final double startY = fullHeight ? editSession.getWorld().getMaxY() : pos.getBlockY() + size;
+        for (double x = pos.getBlockX() + size; x > pos.getBlockX() - size; --x) {
+            for (double z = pos.getBlockZ() + size; z > pos.getBlockZ() - size; --z) {
+                double y = startY;
+                final List<BaseBlock> blockTypes = new ArrayList<BaseBlock>();
+                for (; y > pos.getBlockY() - size; --y) {
+                    final Vector pt = new Vector(x, y, z);
+                    final BaseBlock block = editSession.getBlock(pt);
+                    if (!block.isAir()) {
+                        blockTypes.add(block);
+                        editSession.setBlock(pt, air);
+                    }
+                }
+                Vector pt = new Vector(x, y, z);
+                Collections.reverse(blockTypes);
+                for (int i = 0; i < blockTypes.size();) {
+                    if (editSession.getBlock(pt).getType() == BlockID.AIR) {
+                        editSession.setBlock(pt, blockTypes.get(i++));
+                    }
+                    pt = pt.add(0, 1, 0);
+                }
+            }
+        }
+    }
+}