diff --git a/src/java/com/threerings/miso/client/DisplayMisoScene.java b/src/java/com/threerings/miso/client/DisplayMisoScene.java
index 64e4fb545..3fb299380 100644
--- a/src/java/com/threerings/miso/client/DisplayMisoScene.java
+++ b/src/java/com/threerings/miso/client/DisplayMisoScene.java
@@ -1,23 +1,17 @@
 //
-// $Id: DisplayMisoScene.java,v 1.9 2003/01/31 23:10:45 mdb Exp $
+// $Id: DisplayMisoScene.java,v 1.10 2003/02/12 07:21:15 mdb Exp $
 
 package com.threerings.miso.client;
 
-import java.awt.Rectangle;
-
-import com.threerings.media.tile.ObjectTile;
 import com.threerings.media.tile.Tile;
-
-import com.threerings.miso.client.util.ObjectSet;
+import com.threerings.miso.data.MisoScene;
 import com.threerings.miso.tile.BaseTile;
 
 /**
- * Makes available the information from the {@link MisoSceneModel} in a
- * form that is amenable to actually displaying the scene in a user
- * interface. As with all display scene implementations, the information
- * provided is read-only and should never be modified by the caller.
+ * Extends the {@link MisoScene} with functionality needed only by
+ * entities that plan to display a miso scene.
  */
-public interface DisplayMisoScene
+public interface DisplayMisoScene extends MisoScene
 {
     /**
      * Returns the base tile at the specified coordinates.
@@ -29,12 +23,6 @@ public interface DisplayMisoScene
      */
     public Tile getFringeTile (int x, int y);
 
-    /**
-     * Populates the supplied object set with info on all objects whose
-     * origin falls in the requested region.
-     */
-    public void getObjects (Rectangle region, ObjectSet set);
-
     /**
      * Returns true if the supplied traverser can traverse the specified
      * tile coordinate. The traverser is whatever object is passed along
diff --git a/src/java/com/threerings/miso/client/DisplayMisoSceneImpl.java b/src/java/com/threerings/miso/client/SimpleDisplayMisoSceneImpl.java
similarity index 50%
rename from src/java/com/threerings/miso/client/DisplayMisoSceneImpl.java
rename to src/java/com/threerings/miso/client/SimpleDisplayMisoSceneImpl.java
index 509c2fc51..38bfb12f8 100644
--- a/src/java/com/threerings/miso/client/DisplayMisoSceneImpl.java
+++ b/src/java/com/threerings/miso/client/SimpleDisplayMisoSceneImpl.java
@@ -1,32 +1,29 @@
 //
-// $Id: DisplayMisoSceneImpl.java,v 1.66 2003/02/04 21:39:28 mdb Exp $
+// $Id: SimpleDisplayMisoSceneImpl.java,v 1.1 2003/02/12 07:21:15 mdb Exp $
 
 package com.threerings.miso.client;
 
-import java.awt.Rectangle;
-
-import java.util.ArrayList;
-import java.util.Random;
+import java.util.HashMap;
 
 import com.threerings.media.tile.NoSuchTileException;
 import com.threerings.media.tile.NoSuchTileSetException;
 import com.threerings.media.tile.ObjectTile;
 import com.threerings.media.tile.Tile;
-import com.threerings.media.tile.TileLayer;
 
 import com.threerings.miso.Log;
 import com.threerings.miso.client.util.ObjectSet;
-import com.threerings.miso.data.MisoSceneModel;
 import com.threerings.miso.data.ObjectInfo;
+import com.threerings.miso.data.SimpleMisoSceneImpl;
+import com.threerings.miso.data.SimpleMisoSceneModel;
 import com.threerings.miso.tile.AutoFringer;
 import com.threerings.miso.tile.BaseTile;
-import com.threerings.miso.tile.BaseTileLayer;
 import com.threerings.miso.tile.MisoTileManager;
 
 /**
- * The default implementation of the {@link DisplayMisoScene} interface.
+ * An implementation of the {@link DisplayMisoScene} interface that uses a
+ * simple miso scene model.
  */
-public class DisplayMisoSceneImpl
+public class SimpleDisplayMisoSceneImpl extends SimpleMisoSceneImpl
     implements DisplayMisoScene
 {
     /**
@@ -37,151 +34,28 @@ public class DisplayMisoSceneImpl
      * @param model the scene data that we'll be displaying.
      * @param tmgr the tile manager from which to load our tiles.
      */
-    public DisplayMisoSceneImpl (MisoSceneModel model, MisoTileManager tmgr)
+    public SimpleDisplayMisoSceneImpl (SimpleMisoSceneModel model,
+                                       MisoTileManager tmgr)
     {
-        this(model);
-        setTileManager(tmgr);
-    }
+        super(model);
 
-    /**
-     * Constructs an instance that will be used to display the supplied
-     * miso scene data. The tiles identified by the scene model will not
-     * be loaded until a tile manager is provided via {@link
-     * #setTileManager}.
-     *
-     * @param model the scene data that we'll be displaying.
-     */
-    public DisplayMisoSceneImpl (MisoSceneModel model)
-    {
-        setMisoSceneModel(model);
-    }
-
-    /**
-     * Provides this display miso scene with a tile manager from which it
-     * can load up all of its tiles.
-     */
-    public void setTileManager (MisoTileManager tmgr)
-    {
         _tmgr = tmgr;
         _fringer = tmgr.getAutoFringer();
-        populateLayers();
-    }
-
-    // documentation inherited from interface
-    public BaseTile getBaseTile (int x, int y)
-    {
-        return _base.getTile(x, y);
-    }
-
-    // documentation inherited from interface
-    public Tile getFringeTile (int x, int y)
-    {
-        return _fringe.getTile(x, y);
-    }
-
-    // documentation inherited from interface
-    public void getObjects (Rectangle region, ObjectSet set)
-    {
-        // iterate over all of our objects, creating and including scene
-        // objects for those that intersect the region
-        int ocount = _objects.size();
-        for (int ii = 0; ii < ocount; ii++) {
-            DisplayObjectInfo scobj = (DisplayObjectInfo)_objects.get(ii);
-            if (region.contains(scobj.x, scobj.y)) {
-                set.insert(scobj);
-            }
-        }
-    }
-
-    // documentation inherited from interface
-    public boolean canTraverse (Object trav, int x, int y)
-    {
-        BaseTile tile = getBaseTile(x, y);
-        return (((tile == null) || tile.isPassable()) &&
-                !_covered[y*_model.width+x]);
-    }
-
-    /**
-     * Return a string representation of this Miso scene object.
-     */
-    public String toString ()
-    {
-        StringBuffer buf = new StringBuffer();
-        buf.append("[width=").append(_base.getWidth());
-        buf.append(", height=").append(_base.getHeight());
-        return buf.append("]").toString();
-    }
-
-    /**
-     * Instructs this miso scene to use the supplied model instead of its
-     * current model. This should be followed up by a called to {@link
-     * #setTileManager} or {@link #populateLayers} if a tile manager has
-     * already been provided.
-     */
-    protected void setMisoSceneModel (MisoSceneModel model)
-    {
-        _model = model;
 
         int swid = _model.width;
         int shei = _model.height;
 
         // create the individual tile layer objects
-        _base = new BaseTileLayer(new BaseTile[swid*shei], swid, shei);
-        _fringe = new TileLayer(new Tile[swid*shei], swid, shei);
+        _base = new BaseTile[swid*shei];
+        _fringe = new Tile[swid*shei];
         _covered = new boolean[swid*shei];
 
-        // create display object infos for our uninteresting objects
-        int ocount = (_model.objectTileIds == null) ? 0 :
-            _model.objectTileIds.length;
-        for (int ii = 0; ii < ocount; ii++) {
-            _objects.add(new DisplayObjectInfo(_model.objectTileIds[ii],
-                                               _model.objectXs[ii],
-                                               _model.objectYs[ii]));
-        }
-
-        // create display object infos for our interesting objects
-        for (int ii = 0, ll = _model.objectInfo.length; ii < ll; ii++) {
-            _objects.add(new DisplayObjectInfo(_model.objectInfo[ii]));
-        }
-    }
-
-    /**
-     * Populates the tile layers with tiles from the tile manager.
-     */
-    protected void populateLayers ()
-    {
-        int swid = _base.getWidth();
-        int shei = _base.getHeight();
-
-        // if we have a fringer, fill in our fringe
-        if (_fringer != null) {
-            _fringer.fringe(_model, _fringe, _rando);
-        }
-
-        // populate the base and fringe layers
+        // load up the tiles for our base layer
         for (int column = 0; column < shei; column++) {
             for (int row = 0; row < swid; row++) {
-                // first do the base layer
-                int tsid = _model.getBaseTile(column, row);
-                if (tsid > 0) {
-                    int tid = (tsid & 0xFFFF);
-                    tsid >>= 16;
-                    // this is a bit magical, but the tile manager will
-                    // fetch tiles from the tileset repository and the
-                    // tile set id from which we request this tile must
-                    // map to a base tile as provided by the repository,
-                    // so we just cast it to a base tile and know that all
-                    // is well
-                    try {
-                        BaseTile mtile = (BaseTile)_tmgr.getTile(tsid, tid);
-                        _base.setTile(column, row, mtile);
-                    } catch (NoSuchTileSetException nste) {
-                        Log.warning("Scene contains non-existent tileset " +
-                                    "[tsid=" + tsid + ", tid=" + tid + "].");
-                    } catch (NoSuchTileException nste) {
-                        Log.warning("Scene contains non-existent tile " +
-                                    "[tsid=" + tsid + ", tid=" + tid + "].");
-                    }
+                int fqTileId = getBaseTileId(column, row);
+                if (fqTileId > 0) {
+                    populateBaseTile(fqTileId, column, row);
                 }
             }
         }
@@ -195,9 +69,108 @@ public class DisplayMisoSceneImpl
         }
     }
 
+    // documentation inherited from interface
+    public void setBaseTile (int fqTileId, int x, int y)
+    {
+        super.setBaseTile(fqTileId, x, y);
+        populateBaseTile(fqTileId, x, y);
+    }
+
+    // documentation inherited from interface
+    public ObjectInfo addObject (int fqTileId, int x, int y)
+    {
+        DisplayObjectInfo info = (DisplayObjectInfo)
+            super.addObject(fqTileId, x, y);
+        populateObject(info);
+        return info;
+    }
+
+    // documentation inherited from interface
+    public boolean removeObject (ObjectInfo info)
+    {
+        if (super.removeObject(info)) {
+            // clear out this object's "shadow"
+            DisplayObjectInfo dinfo = (DisplayObjectInfo)info;
+            setObjectTileFootprint(dinfo.tile, dinfo.x, dinfo.y, false);
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    // documentation inherited from interface
+    public BaseTile getBaseTile (int x, int y)
+    {
+        if (x < 0 || y < 0 || x >= _model.width || y >= _model.height) {
+            return null;
+        }
+        return _base[y*_model.width+x];
+    }
+
+    // documentation inherited from interface
+    public Tile getFringeTile (int x, int y)
+    {
+        if (x < 0 || y < 0 || x >= _model.width || y >= _model.height) {
+            return null;
+        }
+
+        // if we have not yet composed this fringe tile, do so
+        int idx = y * _model.width + x;
+        if (_fringe[idx] == null) {
+            _fringe[idx] = _fringer.getFringeTile(this, x, y, _masks, _rando);
+            // make a note of non-fringed tiles that have been resolved
+            // but have no fringe tile
+            if (_fringe[idx] == null) {
+                _fringe[idx] = _nullFringe;
+            }
+        }
+
+        return (_fringe[idx] == _nullFringe) ? null : _fringe[idx];
+    }
+
+    // documentation inherited from interface
+    public boolean canTraverse (Object trav, int x, int y)
+    {
+        BaseTile tile = getBaseTile(x, y);
+        return (((tile == null) || tile.isPassable()) &&
+                !_covered[y*_model.width+x]);
+    }
+
     /**
-     * Called to populate an object with its object tile when we have been
-     * configured with a tile manager from which to obtain such things.
+     * Called to populate a coordinate with its base tile.
+     */
+    protected void populateBaseTile (int fqTileId, int x, int y)
+    {
+        if (x < 0 || y < 0 || x >= _model.width || y >= _model.height) {
+            // nothing doing
+            return;
+        }
+        int tsid = fqTileId >> 16, tid = (fqTileId & 0xFFFF);
+
+        // this is a bit magical, but the tile manager will fetch tiles
+        // from the tileset repository and the tile set id from which we
+        // request this tile must map to a base tile as provided by the
+        // repository, so we just cast it to a base tile and know that all
+        // is well
+        String errmsg = null;
+        try {
+            _base[y*_model.width+x] = (BaseTile)_tmgr.getTile(tsid, tid);
+        } catch (ClassCastException cce) {
+            errmsg = "Scene contains non-base tile in base layer";
+        } catch (NoSuchTileSetException nste) {
+            errmsg = "Scene contains non-existent tileset";
+        } catch (NoSuchTileException nste) {
+            errmsg = "Scene contains non-existent tile";
+        }
+
+        if (errmsg != null) {
+            Log.warning(errmsg + " [tsid=" + tsid + ", tid=" + tid +
+                        ", x=" + x + ", y=" + y + "].");
+        }
+    }
+
+    /**
+     * Called to populate an object with its object tile.
      */
     protected boolean populateObject (DisplayObjectInfo info)
     {
@@ -207,12 +180,10 @@ public class DisplayMisoSceneImpl
             return true;
         } catch (NoSuchTileException nste) {
             Log.warning("Scene contains non-existent object tile " +
-                        "[info=" + info + ", tsid=" + tsid +
-                        ", tid=" + tid + "].");
+                        "[info=" + info + "].");
         } catch (NoSuchTileSetException te) {
-            Log.warning("Scene contains non-existent object tile " +
-                        "[info=" + info + ", tsid=" + tsid +
-                        ", tid=" + tid + "].");
+            Log.warning("Scene contains non-existent object tileset " +
+                        "[info=" + info + "].");
         }
         return false;
     }
@@ -284,27 +255,36 @@ public class DisplayMisoSceneImpl
         // ", sy=" + y + ", ex=" + endx + ", ey=" + endy + "].");
     }
 
+    // documentation inherited
+    protected ObjectInfo createObjectInfo (int tileId, int x, int y)
+    {
+        return new DisplayObjectInfo(tileId, x, y);
+    }
+
+    // documentation inherited
+    protected ObjectInfo createObjectInfo (ObjectInfo source)
+    {
+        return new DisplayObjectInfo(source);
+    }
+
     /** The tile manager from which we load tiles. */
     protected MisoTileManager _tmgr;
 
-    /** The miso scene model from which we obtain our data. */
-    protected MisoSceneModel _model;
-
     /** The base layer of tiles. */
-    protected BaseTileLayer _base;
+    protected BaseTile[] _base;
 
     /** The fringe layer of tiles. */
-    protected TileLayer _fringe;
+    protected Tile[] _fringe;
+
+    /** Contains cached fringe mask tiles. TODO: LRU this or something. */
+    protected HashMap _masks = new HashMap();
+
+    /** Used to identify non-existent fringe tiles. */
+    protected Tile _nullFringe;
 
     /** Information on which tiles are covered by object tiles. */
     protected boolean[] _covered;
 
-    /** The scene object records. */
-    protected ArrayList _objects = new ArrayList();
-
     /** The autofringer. */
     protected AutoFringer _fringer;
-
-    /** A random number generator for filling random base tiles and fringes. */
-    protected Random _rando = new Random();
 }
diff --git a/src/java/com/threerings/miso/client/VirtualDisplayMisoSceneImpl.java b/src/java/com/threerings/miso/client/VirtualDisplayMisoSceneImpl.java
new file mode 100644
index 000000000..ed0644360
--- /dev/null
+++ b/src/java/com/threerings/miso/client/VirtualDisplayMisoSceneImpl.java
@@ -0,0 +1,82 @@
+//
+// $Id: VirtualDisplayMisoSceneImpl.java,v 1.1 2003/02/12 07:21:15 mdb Exp $
+
+package com.threerings.miso.client;
+
+import java.awt.Rectangle;
+
+import com.threerings.media.tile.Tile;
+
+import com.threerings.miso.client.util.ObjectSet;
+import com.threerings.miso.data.MisoSceneModel;
+import com.threerings.miso.data.ObjectInfo;
+import com.threerings.miso.tile.BaseTile;
+
+/**
+ * Provides a useful base class for "virtual" {@link DisplayMisoScene}
+ * implementations. These return tiles based on some algorithm rather than
+ * a repository of predefined tile data.
+ */
+public class VirtualDisplayMisoSceneImpl
+    implements DisplayMisoScene
+{
+    // documentation inherited from interface
+    public int getBaseTileId (int x, int y)
+    {
+        return -1;
+    }
+
+    // documentation inherited from interface
+    public void getObjects (Rectangle region, ObjectSet set)
+    {
+        // nothing doing
+    }
+
+    // documentation inherited from interface
+    public void setBaseTile (int fqTileId, int x, int y)
+    {
+        // nothing doing
+    }
+
+    // documentation inherited from interface
+    public void setBaseTiles (Rectangle r, int setId, int setSize)
+    {
+        // nothing doing
+    }
+
+    // documentation inherited from interface
+    public ObjectInfo addObject (int fqTileId, int x, int y)
+    {
+        return null;
+    }
+
+    // documentation inherited from interface
+    public boolean removeObject (ObjectInfo info)
+    {
+        return false;
+    }
+
+    // documentation inherited from interface
+    public MisoSceneModel getSceneModel ()
+    {
+        return null;
+    }
+
+    // documentation inherited from interface
+    public BaseTile getBaseTile (int x, int y)
+    {
+        return null;
+    }
+
+    // documentation inherited from interface
+    public Tile getFringeTile (int x, int y)
+    {
+        return null;
+    }
+
+    // documentation inherited from interface
+    public boolean canTraverse (Object traverser, int x, int y)
+    {
+        return true;
+    }
+}