Moved the polygonization code to the specific regions that are being polygonized.

Also, maxPoints no longer has confusing semantics.

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

@@ -19,9 +19,12 @@
 
 package com.sk89q.worldedit.regions;
 
+import java.util.ArrayList;
 import java.util.Iterator;
+import java.util.List;
 
 import com.sk89q.worldedit.BlockVector;
+import com.sk89q.worldedit.BlockVector2D;
 import com.sk89q.worldedit.LocalWorld;
 import com.sk89q.worldedit.Vector;
 
@@ -69,4 +72,23 @@ public abstract class AbstractRegion implements Region {
             return null;
         }
     }
+
+    @Override
+    public List<BlockVector2D> polygonize(int maxPoints) {
+        if (maxPoints >= 0 && maxPoints < 4) {
+            throw new IllegalArgumentException("Cannot polygonize an AbstractRegion with no overridden polygonize method into less than 4 points.");
+        }
+
+        final BlockVector min = getMinimumPoint().toBlockVector();
+        final BlockVector max = getMaximumPoint().toBlockVector();
+
+        final List<BlockVector2D> points = new ArrayList<BlockVector2D>(4);
+
+        points.add(new BlockVector2D(min.getX(), min.getZ()));
+        points.add(new BlockVector2D(min.getX(), max.getZ()));
+        points.add(new BlockVector2D(max.getX(), max.getZ()));
+        points.add(new BlockVector2D(max.getX(), min.getZ()));
+
+        return points;
+    }
 }

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

@@ -19,8 +19,10 @@
 
 package com.sk89q.worldedit.regions;
 
+import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Set;
 
 import com.sk89q.worldedit.BlockVector;
@@ -408,4 +410,25 @@ public class CylinderRegion extends AbstractRegion implements FlatRegion {
     public CylinderRegion clone() {
         return (CylinderRegion) super.clone();
     }
+
+    @Override
+    public List<BlockVector2D> polygonize(int maxPoints) {
+        final Vector2D radius = getRadius();
+        int nPoints = (int) Math.ceil(Math.PI*radius.length());
+
+        // These strange semantics for maxPoints are copied from the selectSecondary method.
+        if (maxPoints >= 0 && nPoints >= maxPoints) {
+            nPoints = maxPoints - 1;
+        }
+
+        final List<BlockVector2D> points = new ArrayList<BlockVector2D>(nPoints);
+        for (int i = 0; i < nPoints; ++i) {
+            double angle = i * (2.0 * Math.PI) / nPoints;
+            final Vector2D pos = new Vector2D(Math.cos(angle), Math.sin(angle));
+            final BlockVector2D blockVector2D = pos.multiply(radius).add(center).toBlockVector2D();
+            points.add(blockVector2D);
+        }
+
+        return points;
+    }
 }

src/main/java/com/sk89q/worldedit/regions/Polygonal2DRegion.java

@@ -530,4 +530,13 @@ public class Polygonal2DRegion extends AbstractRegion implements FlatRegion {
         clone.points = new ArrayList<BlockVector2D>(points);
         return clone; 
     }
+
+    @Override
+    public List<BlockVector2D> polygonize(int maxPoints) {
+        if (maxPoints >= 0 && maxPoints < points.size()) {
+            throw new IllegalArgumentException("Cannot polygonize a this Polygonal2DRegion into the amount of points given.");
+        }
+
+        return points;
+    }
 }

src/main/java/com/sk89q/worldedit/regions/Polygonal2DRegionSelector.java

@@ -19,7 +19,6 @@
 
 package com.sk89q.worldedit.regions;
 
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import com.sk89q.worldedit.BlockVector;
@@ -29,7 +28,6 @@ import com.sk89q.worldedit.LocalPlayer;
 import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.LocalWorld;
 import com.sk89q.worldedit.Vector;
-import com.sk89q.worldedit.Vector2D;
 import com.sk89q.worldedit.cui.CUIRegion;
 import com.sk89q.worldedit.cui.SelectionMinMaxEvent;
 import com.sk89q.worldedit.cui.SelectionPoint2DEvent;
@@ -67,33 +65,6 @@ public class Polygonal2DRegionSelector implements RegionSelector, CUIRegion {
 
             pos1 = polygonal2DRegionSelector.pos1;
             region = new Polygonal2DRegion(polygonal2DRegionSelector.region);
-        } else if (oldSelector instanceof CylinderRegionSelector) {
-            final CylinderRegionSelector cylinderRegionSelector = (CylinderRegionSelector) oldSelector;
-
-            final CylinderRegion oldRegion = cylinderRegionSelector.region;
-
-            final Vector2D radius = oldRegion.getRadius();
-            final Vector2D center = oldRegion.getCenter().toVector2D();
-            int nPoints = (int) Math.ceil(Math.PI*radius.length());
-
-            // These strange semantics for maxPoints are copied from the selectSecondary method.
-            if (maxPoints > -1 && nPoints >= maxPoints) {
-                nPoints = maxPoints - 1;
-            }
-
-            final List<BlockVector2D> points = new ArrayList<BlockVector2D>(nPoints);
-            for (int i = 0; i < nPoints; ++i) {
-                double angle = i * (2.0 * Math.PI) / nPoints;
-                final Vector2D pos = new Vector2D(Math.cos(angle), Math.sin(angle));
-                final BlockVector2D blockVector2D = pos.multiply(radius).add(center).toBlockVector2D();
-                points.add(blockVector2D);
-            }
-
-            final int minY = oldRegion.getMinimumY();
-
-            pos1 = points.get(0).toVector(minY).toBlockVector();
-            region = new Polygonal2DRegion(oldRegion.getWorld(), points, minY, oldRegion.getMaximumY());
-
         } else {
             final Region oldRegion;
             try {
@@ -102,20 +73,12 @@ public class Polygonal2DRegionSelector implements RegionSelector, CUIRegion {
                 return;
             }
 
-            BlockVector min = oldRegion.getMinimumPoint().toBlockVector();
+            final int minY = oldRegion.getMinimumPoint().getBlockY();
-            BlockVector max = oldRegion.getMaximumPoint().toBlockVector();
+            final int maxY = oldRegion.getMaximumPoint().getBlockY();
 
-            int minY = min.getBlockY();
+            List<BlockVector2D> points = oldRegion.polygonize(maxPoints);
-            int maxY = max.getBlockY();
 
-            List<BlockVector2D> points = new ArrayList<BlockVector2D>(4);
+            pos1 = points.get(0).toVector(minY).toBlockVector();
-
-            points.add(new BlockVector2D(min.getX(), min.getZ()));
-            points.add(new BlockVector2D(min.getX(), max.getZ()));
-            points.add(new BlockVector2D(max.getX(), max.getZ()));
-            points.add(new BlockVector2D(max.getX(), min.getZ()));
-
-            pos1 = min;
             region = new Polygonal2DRegion(oldRegion.getWorld(), points, minY, maxY);
         }
     }
@@ -148,7 +111,7 @@ public class Polygonal2DRegionSelector implements RegionSelector, CUIRegion {
                 return false;
             }
 
-            if (maxPoints > -1 && points.size() >= maxPoints) {
+            if (maxPoints >= 0 && points.size() > maxPoints) {
                 return false;
             }
         }

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

@@ -20,9 +20,12 @@
 package com.sk89q.worldedit.regions;
 
 import com.sk89q.worldedit.BlockVector;
+import com.sk89q.worldedit.BlockVector2D;
 import com.sk89q.worldedit.LocalWorld;
 import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.Vector2D;
+
+import java.util.List;
 import java.util.Set;
 
 /**
@@ -142,4 +145,12 @@ public interface Region extends Iterable<BlockVector>, Cloneable {
     public void setWorld(LocalWorld world);
 
     public Region clone();
+
+    /**
+     * Polygonizes a cross-section or a 2D projection of the region orthogonal to the Y axis.
+     *
+     * @param maxPoints maximum number of points to generate. -1 for no limit.
+     * @return the points.
+     */
+    public List<BlockVector2D> polygonize(int maxPoints);
 }