EarthManip: add a TetherCallback

src/applications/osgearth_manip/osgearth_manip.cpp

@@ -49,6 +49,22 @@ using namespace osgEarth::Annotation;
 
 namespace
 {
+    /**
+     * Tether callback test.
+     */
+    struct TetherCB : public EarthManipulator::TetherCallback
+    {
+        void operator()(osg::Node* node)
+        {
+            if ( node ) {
+                OE_WARN << "Tether on\n";
+            }
+            else {
+                OE_WARN << "Tether off\n";
+            }
+        }
+    };
+
     /**
      * Builds our help menu UI.
      */
@@ -429,6 +445,8 @@ int main(int argc, char** argv)
         osgGA::GUIEventAdapter::MODKEY_SHIFT );
 
     manip->getSettings()->setArcViewpointTransitions( true );    
+
+    manip->setTetherCallback( new TetherCB() );
 
     viewer.addEventHandler(new FlyToViewpointHandler( manip ));
     viewer.addEventHandler(new LockAzimuthHandler('u', manip));

src/osgEarthUtil/EarthManipulator

@@ -611,6 +611,18 @@ namespace osgEarth { namespace Util
          */
         void setTetherNode( osg::Node* node, double duration_s =0.0  );
 
+        /**
+         * Sets a callback to be invoked upon a tether or tether break
+         */
+        class TetherCallback : public osg::Referenced {
+        public:
+            virtual void operator()(osg::Node* tetherNode) { }
+        protected:
+            virtual ~TetherCallback() { }
+        };
+        void setTetherCallback(TetherCallback* cb) { _tetherCallback = cb; }
+        TetherCallback* getTetherCallback() { return _tetherCallback.get(); }
+
         /**
          * Gets the node to which the camera is tethered, or NULL if tethering is
          * disabled.
@@ -689,7 +701,7 @@ namespace osgEarth { namespace Util
          */
         void  setFindNodeTraversalMask( const osg::Node::NodeMask & nodeMask ) { _findNodeTraversalMask = nodeMask; }
 
-    public: // osgGA::MatrixManipulator
+    public: // osgGA::CameraManipulator
 
         virtual const char* className() const { return "EarthManipulator"; }
 
@@ -1000,6 +1012,8 @@ namespace osgEarth { namespace Util
         // Traversal mask used in established and dtor methods to find MapNode and CoordinateSystemNode
         osg::Node::NodeMask  _findNodeTraversalMask;
 
+        osg::ref_ptr<TetherCallback> _tetherCallback;
+
         void collisionDetect();
     };
 

src/osgEarthUtil/EarthManipulator.cpp

@@ -1168,6 +1168,12 @@ EarthManipulator::setTetherNode( osg::Node* node, double duration_s )
         Viewpoint destVP = getTetherNodeViewpoint();
         setViewpoint( destVP, duration_s );
     }
+
+    // invoke the callback if set
+    if ( _tetherCallback.valid() )
+    {
+        (*_tetherCallback.get())( _tether_node.get() );
+    }
 }