Re-add smooth filtering via a mask.

Instead of trying to maintain a list of "natural terrain blocks", just
let the user specify a mask of blocks to use for the height map filter.

https://gfycat.com/severaljauntycondor

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

@@ -592,10 +592,25 @@ public class EditSession implements Extent, AutoCloseable {
      * @return height of highest block found or 'minY'
      */
     public int getHighestTerrainBlock(int x, int z, int minY, int maxY) {
+        return getHighestTerrainBlock(x, z, minY, maxY, null);
+    }
+
+    /**
+     * Returns the highest solid 'terrain' block.
+     *
+     * @param x the X coordinate
+     * @param z the Z coordinate
+     * @param minY minimal height
+     * @param maxY maximal height
+     * @param filter a mask of blocks to consider, or null to consider any solid (movement-blocking) block
+     * @return height of highest block found or 'minY'
+     */
+    public int getHighestTerrainBlock(int x, int z, int minY, int maxY, Mask filter) {
         for (int y = maxY; y >= minY; --y) {
             BlockVector3 pt = BlockVector3.at(x, y, z);
-            BlockState block = getBlock(pt);
-            if (block.getBlockType().getMaterial().isMovementBlocker()) {
+            if (filter == null
+                    ? getBlock(pt).getBlockType().getMaterial().isMovementBlocker()
+                    : filter.test(pt)) {
                 return y;
             }
         }

worldedit-core/src/main/java/com/sk89q/worldedit/command/BrushCommands.java

@@ -42,6 +42,7 @@ import com.sk89q.worldedit.command.util.CreatureButcher;
 import com.sk89q.worldedit.entity.Player;
 import com.sk89q.worldedit.extent.clipboard.Clipboard;
 import com.sk89q.worldedit.function.mask.BlockTypeMask;
+import com.sk89q.worldedit.function.mask.Mask;
 import com.sk89q.worldedit.function.pattern.BlockPattern;
 import com.sk89q.worldedit.function.pattern.Pattern;
 import com.sk89q.worldedit.math.BlockVector3;
@@ -158,24 +159,24 @@ public class BrushCommands {
 
     @Command(
         aliases = { "smooth" },
-        usage = "[size] [iterations]",
+        usage = "[size] [iterations] [filter]",
         desc = "Choose the terrain softener brush",
         help =
-            "Chooses the terrain softener brush.",
+            "Chooses the terrain softener brush. Optionally, specify a mask of blocks to be used for the heightmap.\n" +
+            "For example, '/brush smooth 2 4 grass_block,dirt,stone'.",
         min = 0,
-        max = 2
+        max = 3
     )
     @CommandPermissions("worldedit.brush.smooth")
     public void smoothBrush(Player player, LocalSession session, EditSession editSession,
-                            @Optional("2") double radius, @Optional("4") int iterations) throws WorldEditException {
-
+                            @Optional("2") double radius, @Optional("4") int iterations, @Optional Mask mask) throws WorldEditException {
         worldEdit.checkMaxBrushRadius(radius);
 
         BrushTool tool = session.getBrushTool(player.getItemInHand(HandSide.MAIN_HAND).getType());
         tool.setSize(radius);
-        tool.setBrush(new SmoothBrush(iterations), "worldedit.brush.smooth");
+        tool.setBrush(new SmoothBrush(iterations, mask), "worldedit.brush.smooth");
 
-        player.print(String.format("Smooth brush equipped (%.0f x %dx, using any block).", radius, iterations));
+        player.print(String.format("Smooth brush equipped (%.0f x %dx, using %s).", radius, iterations, mask == null ? "any block" : "filter"));
     }
 
     @Command(

worldedit-core/src/main/java/com/sk89q/worldedit/command/RegionCommands.java

@@ -240,17 +240,19 @@ public class RegionCommands {
 
     @Command(
         aliases = { "/smooth" },
-        usage = "[iterations]",
+        usage = "[iterations] [filter]",
         desc = "Smooth the elevation in the selection",
         help =
-            "Smooths the elevation in the selection.",
+            "Smooths the elevation in the selection.\n" +
+            "Optionally, restricts the height map to a set of blocks specified with mask syntax.\n" +
+            "For example, '//smooth 1 grass_block,dirt,stone' would only smooth natural surface terrain.",
         min = 0,
-        max = 1
+        max = 2
     )
     @CommandPermissions("worldedit.region.smooth")
     @Logging(REGION)
-    public void smooth(Player player, EditSession editSession, @Selection Region region, @Optional("1") int iterations) throws WorldEditException {
-        HeightMap heightMap = new HeightMap(editSession, region);
+    public void smooth(Player player, EditSession editSession, @Selection Region region, @Optional("1") int iterations, @Optional Mask mask) throws WorldEditException {
+        HeightMap heightMap = new HeightMap(editSession, region, mask);
         HeightMapFilter filter = new HeightMapFilter(new GaussianKernel(5, 1.0));
         int affected = heightMap.applyFilter(filter, iterations);
         player.print("Terrain's height map smoothed. " + affected + " block(s) changed.");

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

@@ -21,6 +21,7 @@ package com.sk89q.worldedit.command.tool.brush;
 
 import com.sk89q.worldedit.EditSession;
 import com.sk89q.worldedit.MaxChangedBlocksException;
+import com.sk89q.worldedit.function.mask.Mask;
 import com.sk89q.worldedit.function.pattern.Pattern;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.math.Vector3;
@@ -31,12 +32,20 @@ import com.sk89q.worldedit.regions.CuboidRegion;
 import com.sk89q.worldedit.regions.Region;
 import com.sk89q.worldedit.util.Location;
 
+import javax.annotation.Nullable;
+
 public class SmoothBrush implements Brush {
 
+    private final Mask mask;
     private int iterations;
 
     public SmoothBrush(int iterations) {
+        this(iterations, null);
+    }
+
+    public SmoothBrush(int iterations, @Nullable Mask mask) {
         this.iterations = iterations;
+        this.mask = mask;
     }
 
     @Override
@@ -45,7 +54,7 @@ public class SmoothBrush implements Brush {
         Location min = new Location(editSession.getWorld(), posDouble.subtract(size, size, size));
         BlockVector3 max = posDouble.add(size, size + 10, size).toBlockPoint();
         Region region = new CuboidRegion(editSession.getWorld(), min.toVector().toBlockPoint(), max);
-        HeightMap heightMap = new HeightMap(editSession, region);
+        HeightMap heightMap = new HeightMap(editSession, region, mask);
         HeightMapFilter filter = new HeightMapFilter(new GaussianKernel(5, 1.0));
         heightMap.applyFilter(filter, iterations);
     }

worldedit-core/src/main/java/com/sk89q/worldedit/math/convolution/HeightMap.java

@@ -23,11 +23,14 @@ import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.sk89q.worldedit.EditSession;
 import com.sk89q.worldedit.MaxChangedBlocksException;
+import com.sk89q.worldedit.function.mask.Mask;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.Region;
 import com.sk89q.worldedit.world.block.BlockState;
 import com.sk89q.worldedit.world.block.BlockTypes;
 
+import javax.annotation.Nullable;
+
 /**
  * Allows applications of Kernels onto the region's height map.
  *
@@ -48,7 +51,7 @@ public class HeightMap {
      * @param session an edit session
      * @param region the region
      */
-    public HeightMap(EditSession session, Region region) {
+    public HeightMap(EditSession session, Region region, @Nullable Mask mask) {
         checkNotNull(session);
         checkNotNull(region);
 
@@ -67,7 +70,7 @@ public class HeightMap {
         data = new int[width * height];
         for (int z = 0; z < height; ++z) {
             for (int x = 0; x < width; ++x) {
-                data[z * width + x] = session.getHighestTerrainBlock(x + minX, z + minZ, minY, maxY);
+                data[z * width + x] = session.getHighestTerrainBlock(x + minX, z + minZ, minY, maxY, mask);
             }
         }
     }