Fix gravity brush expecting blocks to be set instantly

core/src/main/java/com/boydti/fawe/Fawe.java

@@ -27,6 +27,7 @@ import com.sk89q.worldedit.command.ClipboardCommands;
 import com.sk89q.worldedit.command.SchematicCommands;
 import com.sk89q.worldedit.command.ScriptingCommands;
 import com.sk89q.worldedit.command.composition.SelectionCommand;
+import com.sk89q.worldedit.command.tool.brush.GravityBrush;
 import com.sk89q.worldedit.extension.platform.CommandManager;
 import com.sk89q.worldedit.extension.platform.PlatformManager;
 import com.sk89q.worldedit.extent.clipboard.BlockArrayClipboard;
@@ -237,6 +238,8 @@ public class Fawe {
             SchematicCommands.inject();
             ScriptingCommands.inject();
             SelectionCommand.inject();
+            // Brushes
+            GravityBrush.inject();
             // Visitors
             BreadthFirstSearch.inject();
             DownwardVisitor.inject();

core/src/main/java/com/sk89q/worldedit/command/tool/brush/GravityBrush.java

@@ -0,0 +1,76 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser 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 Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.command.tool.brush;
+
+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.function.pattern.Pattern;
+
+public class GravityBrush implements Brush {
+
+    private final boolean fullHeight;
+
+    public GravityBrush(boolean fullHeight) {
+        this.fullHeight = fullHeight;
+    }
+
+    @Override
+    public void build(EditSession editSession, Vector position, Pattern pattern, double sizeDouble) throws MaxChangedBlocksException {
+        int size = (int) sizeDouble;
+        BaseBlock air = new BaseBlock(BlockID.AIR, 0);
+        int endY = position.getBlockY() + size;
+        int startPerformY = Math.max(0, position.getBlockY() - size);
+        int startCheckY = fullHeight ? 0 : startPerformY;
+        Vector mutablePos = new Vector(0, 0, 0);
+        for (int x = position.getBlockX() + size; x > position.getBlockX() - size; --x) {
+            for (int z = position.getBlockZ() + size; z > position.getBlockZ() - size; --z) {
+                int freeSpot = startCheckY;
+                for (int y = startCheckY; y <= endY; y++) {
+                    if (y < startPerformY) {
+                        if (editSession.getLazyBlock(x, y, z) != EditSession.nullBlock) {
+                            freeSpot = y + 1;
+                        }
+                        continue;
+                    }
+                    BaseBlock block = editSession.getLazyBlock(x, y, z);
+                    if (block != EditSession.nullBlock) {
+                        if (freeSpot != y) {
+                            mutablePos.x = x;
+                            mutablePos.y = freeSpot;
+                            mutablePos.z = z;
+                            editSession.setBlock(mutablePos, block);
+                            mutablePos.y = y;
+                            editSession.setBlock(mutablePos, EditSession.nullBlock);
+                        }
+                        freeSpot++;
+                    }
+                }
+            }
+        }
+    }
+
+    public static Class<?> inject() {
+        return GravityBrush.class;
+    }
+
+}