Added a //generatebiome command, which uses formulae to generate free-form biomes.

Shorthands: //genbiome, //gb

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

@@ -46,6 +46,7 @@
 import com.sk89q.worldedit.regions.CuboidRegion;
 import com.sk89q.worldedit.regions.Region;
 import com.sk89q.worldedit.regions.RegionOperationException;
+import com.sk89q.worldedit.shape.ArbitraryBiomeShape;
 import com.sk89q.worldedit.shape.ArbitraryShape;
 import com.sk89q.worldedit.shape.RegionShape;
 import com.sk89q.worldedit.shape.WorldEditExpressionEnvironment;
@@ -3019,4 +3020,38 @@ private void recurseHollow(Region region, BlockVector origin, Set<BlockVector> o
         } // while
     }
 
+    public int makeBiomeShape(final Region region, final Vector zero, final Vector unit, final BiomeType biomeType, final String expressionString, final boolean hollow) throws ExpressionException, MaxChangedBlocksException {
+        final Vector2D zero2D = zero.toVector2D();
+        final Vector2D unit2D = unit.toVector2D();
+
+        final Expression expression = Expression.compile(expressionString, "x", "z");
+        expression.optimize();
+
+        final EditSession editSession = this;
+        final WorldEditExpressionEnvironment environment = new WorldEditExpressionEnvironment(editSession, unit, zero);
+        expression.setEnvironment(environment);
+
+        final ArbitraryBiomeShape shape = new ArbitraryBiomeShape(region) {
+            @Override
+            protected BiomeType getBiome(int x, int z, BiomeType defaultBiomeType) {
+                final Vector2D current = new Vector2D(x, z);
+                environment.setCurrentBlock(current.toVector(0));
+                final Vector2D scaled = current.subtract(zero2D).divide(unit2D);
+
+                try {
+                    if (expression.evaluate(scaled.getX(), scaled.getZ()) <= 0) {
+                        return null;
+                    }
+
+                    // TODO: Allow biome setting via a script variable (needs BiomeType<->int mapping)
+                    return defaultBiomeType;
+                } catch (Exception e) {
+                    e.printStackTrace();
+                    return null;
+                }
+            }
+        };
+
+        return shape.generate(this, biomeType, hollow);
+    }
 }

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

@@ -27,10 +27,12 @@
 import com.sk89q.minecraft.util.commands.CommandContext;
 import com.sk89q.minecraft.util.commands.CommandPermissions;
 import com.sk89q.minecraft.util.commands.Logging;
+import com.sk89q.worldedit.BiomeType;
 import com.sk89q.worldedit.EditSession;
 import com.sk89q.worldedit.LocalPlayer;
 import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
+import com.sk89q.worldedit.Vector2D;
 import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.WorldEditException;
 import com.sk89q.worldedit.expression.ExpressionException;
@@ -415,4 +417,71 @@ public void generate(CommandContext args, LocalSession session, LocalPlayer play
             player.printError(e.getMessage());
         }
     }
+
+    @Command(
+        aliases = { "/generatebiome", "/genbiome", "/gb" },
+        usage = "<block> <expression>",
+        desc = "Sets biome according to a formula.",
+        help =
+            "Generates a shape according to a formula that is expected to\n" +
+            "return positive numbers (true) if the point is inside the shape\n" +
+            "Optionally set type/data to the desired block.\n" +
+            "Flags:\n" +
+            "  -h to generate a hollow shape\n" +
+            "  -r to use raw minecraft coordinates\n" +
+            "  -o is like -r, except offset from placement.\n" +
+            "  -c is like -r, except offset selection center.\n" +
+            "If neither -r nor -o is given, the selection is mapped to -1..1\n" +
+            "See also tinyurl.com/wesyntax.",
+        flags = "hroc",
+        min = 2,
+        max = -1
+    )
+    @CommandPermissions({"worldedit.generation.shape", "worldedit.biome.set"})
+    @Logging(ALL)
+    public void generateBiome(CommandContext args, LocalSession session, LocalPlayer player,
+            EditSession editSession) throws WorldEditException {
+
+        final BiomeType target = we.getServer().getBiomes().get(args.getString(0));
+        final Region region = session.getSelection(player.getWorld());
+
+        final boolean hollow = args.hasFlag('h');
+
+        final String expression = args.getJoinedStrings(1);
+
+        final Vector zero;
+        Vector unit;
+
+        if (args.hasFlag('r')) {
+            zero = Vector.ZERO;
+            unit = Vector.ONE;
+        } else if (args.hasFlag('o')) {
+            zero = session.getPlacementPosition(player);
+            unit = Vector.ONE;
+        } else if (args.hasFlag('c')) {
+            final Vector min = region.getMinimumPoint();
+            final Vector max = region.getMaximumPoint();
+
+            zero = max.add(min).multiply(0.5);
+            unit = Vector.ONE;
+        } else {
+            final Vector min = region.getMinimumPoint();
+            final Vector max = region.getMaximumPoint();
+
+            zero = max.add(min).multiply(0.5);
+            unit = max.subtract(zero);
+
+            if (unit.getX() == 0) unit = unit.setX(1.0);
+            if (unit.getY() == 0) unit = unit.setY(1.0);
+            if (unit.getZ() == 0) unit = unit.setZ(1.0);
+        }
+
+        try {
+            final int affected = editSession.makeBiomeShape(region, zero, unit, target, expression, hollow);
+            player.findFreePosition();
+            player.print("Biome changed to " + target.getName() + ". " + affected + " columns affected.");
+        } catch (ExpressionException e) {
+            player.printError(e.getMessage());
+        }
+    }
 }

src/main/java/com/sk89q/worldedit/shape/ArbitraryBiomeShape.java

@@ -0,0 +1,189 @@
+// $Id$
+/*
+ * WorldEdit
+ * Copyright (C) 2010 sk89q <http://www.sk89q.com> and contributors
+ *
+ * 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.shape;
+
+import com.sk89q.worldedit.BiomeType;
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.Vector2D;
+import com.sk89q.worldedit.regions.CuboidRegion;
+import com.sk89q.worldedit.regions.FlatRegion;
+import com.sk89q.worldedit.regions.Region;
+
+/**
+ * Generates solid and hollow shapes according to materials returned by the
+ * {@link #getBiome} method.
+ *
+ * @author TomyLobo
+ */
+public abstract class ArbitraryBiomeShape {
+    private final FlatRegion extent;
+    private int cacheOffsetX;
+    private int cacheOffsetZ;
+    @SuppressWarnings("FieldCanBeLocal")
+    private int cacheSizeX;
+    private int cacheSizeZ;
+
+    public ArbitraryBiomeShape(Region extent) {
+        if (extent instanceof FlatRegion) {
+            this.extent = (FlatRegion) extent;
+        }
+        else {
+            // TODO: polygonize
+            this.extent = new CuboidRegion(extent.getWorld(), extent.getMinimumPoint(), extent.getMaximumPoint());
+        }
+
+        Vector2D min = extent.getMinimumPoint().toVector2D();
+        Vector2D max = extent.getMaximumPoint().toVector2D();
+
+        cacheOffsetX = min.getBlockX() - 1;
+        cacheOffsetZ = min.getBlockZ() - 1;
+
+        cacheSizeX = (int) (max.getX() - cacheOffsetX + 2);
+        cacheSizeZ = (int) (max.getZ() - cacheOffsetZ + 2);
+
+        cache = new BiomeType[cacheSizeX * cacheSizeZ];
+    }
+
+    protected Iterable<Vector2D> getExtent() {
+        return extent.asFlatRegion();
+    }
+
+
+    /**
+     * Cache entries:
+     * null = unknown
+     * OUTSIDE = outside
+     * else = inside
+     */
+    private final BiomeType[] cache;
+
+    /**
+     * Override this function to specify the shape to generate.
+     *
+     * @param x X coordinate to be queried
+     * @param z Z coordinate to be queried
+     * @param defaultBiomeType The default biome for the current column.
+     * @return material to place or null to not place anything.
+     */
+    protected abstract BiomeType getBiome(int x, int z, BiomeType defaultBiomeType);
+
+    private BiomeType getBiomeCached(int x, int z, BiomeType biomeType) {
+        final int index = (z - cacheOffsetZ) + (x - cacheOffsetX) * cacheSizeZ;
+
+        final BiomeType cacheEntry = cache[index];
+        if (cacheEntry == null) {// unknown, fetch material
+            final BiomeType material = getBiome(x, z, biomeType);
+            if (material == null) {
+                // outside
+                cache[index] = OUTSIDE;
+                return null;
+            }
+
+            cache[index] = material;
+            return material;
+        }
+
+        if (cacheEntry == OUTSIDE) {
+            // outside
+            return null;
+        }
+
+        return cacheEntry;
+    }
+
+    private boolean isInsideCached(int x, int z, BiomeType biomeType) {
+        final int index = (z - cacheOffsetZ) + (x - cacheOffsetX) * cacheSizeZ;
+
+        final BiomeType cacheEntry = cache[index];
+        if (cacheEntry == null) {
+            // unknown block, meaning they must be outside the extent at this stage, but might still be inside the shape
+            return getBiomeCached(x, z, biomeType) != null;
+        }
+
+        return cacheEntry != OUTSIDE;
+    }
+
+    /**
+     * Generates the shape.
+     *
+     * @param editSession The EditSession to use.
+     * @param biomeType The default biome type.
+     * @param hollow Specifies whether to generate a hollow shape.
+     * @return number of affected blocks.
+     */
+    public int generate(EditSession editSession, BiomeType biomeType, boolean hollow) {
+        int affected = 0;
+
+        for (Vector2D position : getExtent()) {
+            int x = position.getBlockX();
+            int z = position.getBlockZ();
+
+            if (!hollow) {
+                final BiomeType material = getBiome(x, z, biomeType);
+                if (material != OUTSIDE) {
+                    editSession.getWorld().setBiome(position, material);
+                    ++affected;
+                }
+
+                continue;
+            }
+
+            final BiomeType material = getBiomeCached(x, z, biomeType);
+            if (material == null) {
+                continue;
+            }
+
+            boolean draw = false;
+            do {
+                if (!isInsideCached(x + 1, z, biomeType)) {
+                    draw = true;
+                    break;
+                }
+                if (!isInsideCached(x - 1, z, biomeType)) {
+                    draw = true;
+                    break;
+                }
+                if (!isInsideCached(x, z + 1, biomeType)) {
+                    draw = true;
+                    break;
+                }
+                if (!isInsideCached(x, z - 1, biomeType)) {
+                    draw = true;
+                    break;
+                }
+            } while (false);
+
+            if (!draw) {
+                continue;
+            }
+
+            editSession.getWorld().setBiome(position, material);
+            ++affected;
+        }
+
+        return affected;
+    }
+
+    private static final BiomeType OUTSIDE = new BiomeType() {
+        public String getName() {
+            throw new UnsupportedOperationException();
+        }
+    };
+}