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/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;
+}