Added a visitor class for performing operations on all instances of

Spatial-derived classes in a scene graph.


git-svn-id: svn+ssh://src.earth.threerings.net/nenya/trunk@40 ed5b42cb-e716-0410-a449-f6a68f950b19

src/java/com/threerings/jme/tools/ModelViewer.java

@@ -95,7 +95,7 @@ import com.jme.util.TextureKey;
 import com.jme.util.TextureManager;
 import com.jme.util.export.binary.BinaryImporter;
 import com.jme.util.geom.Debugger;
-import com.jmex.effects.particles.ParticleMesh;
+import com.jmex.effects.particles.ParticleGeometry;
 
 import com.samskivert.swing.GroupLayout;
 import com.samskivert.swing.Spacer;
@@ -111,6 +111,7 @@ import com.threerings.jme.Log;
 import com.threerings.jme.camera.CameraHandler;
 import com.threerings.jme.model.Model;
 import com.threerings.jme.model.TextureProvider;
+import com.threerings.jme.util.SpatialVisitor;
 
 /**
  * A simple viewer application that allows users to examine models and their
@@ -832,8 +833,8 @@ public class ModelViewer extends JmeCanvasApp
             JPanel bpanel = new JPanel();
             bpanel.add(new JButton(new AbstractAction(
                 _msg.get("m.respawn_particles")) {
-                public void actionPerformed (ActionEvent e) {
+                public void actionPerformed (ActionEvent e) {   
-                    forceRespawn(_spatial);   
+                    _respawner.traverse(_spatial);
                 }
             }));
             bpanel.add(new JButton(new AbstractAction(_msg.get("m.close")) {
@@ -863,21 +864,6 @@ public class ModelViewer extends JmeCanvasApp
             }
         }
         
-        /**
-         * Recursively forces all particles to respawn.
-         */
-        protected void forceRespawn (Spatial spatial)
-        {
-            if (spatial instanceof ParticleMesh) {
-                ((ParticleMesh)spatial).forceRespawn();
-            } else if (spatial instanceof Node) {
-                Node node = (Node)spatial;
-                for (int ii = 0, nn = node.getQuantity(); ii < nn; ii++) {
-                    forceRespawn(node.getChild(ii));
-                }
-            }
-        }
-        
         /** The imported scene. */
         protected Spatial _spatial;
         
@@ -1025,6 +1011,14 @@ public class ModelViewer extends JmeCanvasApp
     protected static Config _config =
         new Config("com/threerings/jme/tools/ModelViewer");
     
+    /** Forces all particle systems to respawn. */
+    protected static SpatialVisitor<ParticleGeometry> _respawner =
+        new SpatialVisitor<ParticleGeometry>(ParticleGeometry.class) {
+        protected void visit (ParticleGeometry geom) {
+            geom.forceRespawn();
+        }
+    };
+    
     /** The number of lines on the grid in each direction. */
     protected static final int GRID_SIZE = 32;
     

src/java/com/threerings/jme/util/SpatialVisitor.java

@@ -0,0 +1,45 @@
+//
+// $Id$
+
+package com.threerings.jme.util;
+
+import com.jme.scene.Node;
+import com.jme.scene.Spatial;
+
+/**
+ * Performs a depth-first scene graph traversal looking for {@link Spatial}s
+ * of a given class.
+ */
+public abstract class SpatialVisitor<T extends Spatial>
+{
+    public SpatialVisitor (Class<T> type)
+    {
+        _type = type;
+    }
+    
+    /**
+     * Traverses the given node in depth-first order, calling {@link #visit}
+     * for each {@link Spatial} of the configured class encountered.
+     */
+    public void traverse (Spatial spatial)
+    {
+        if (_type.isInstance(spatial)) {
+            visit(_type.cast(spatial));
+        }
+        if (spatial instanceof Node) {
+            Node node = (Node)spatial;
+            for (int ii = 0, nn = node.getQuantity(); ii < nn; ii++) {
+                traverse(node.getChild(ii));
+            }
+        }
+    }
+    
+    /**
+     * Called once for each {@link Spatial} of the configured class in the
+     * scene graph.
+     */
+    protected abstract void visit (T child);
+    
+    /** The type of spatial of interest. */
+    protected Class<T> _type;
+}