Added new osgVolume::VolumeScene and osgVolume::MultipassTechnique class shells that will be filled out to provide multi-pass volume rendering that handles mixing of

3D meshes with volume rendering and segmentation of volumes via a user defined hull mesh.

src/osgVolume/VolumeScene.cpp

@@ -0,0 +1,36 @@
+/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2009 Robert Osfield
+ *
+ * This library is open source and may be redistributed and/or modified under
+ * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
+ * (at your option) any later version.  The full license is in LICENSE file
+ * included with this distribution, and on the openscenegraph.org website.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * OpenSceneGraph Public License for more details.
+*/
+
+#include <osgVolume/VolumeScene>
+#include <OpenThreads/ScopedLock>
+
+using namespace osgVolume;
+
+VolumeScene::VolumeScene()
+{
+}
+
+VolumeScene::VolumeScene(const VolumeScene& vs, const osg::CopyOp& copyop):
+    osg::Group(vs,copyop)
+{
+}
+
+
+VolumeScene::~VolumeScene()
+{
+}
+
+void VolumeScene::traverse(osg::NodeVisitor& nv)
+{
+    Group::traverse(nv);
+}