From Wang Rui, "Two small bugs were just found when I was writing examples for my book

in process: a wrong definition of the OSG_FATAL macro, and wrong logic
inside the KeySwitchMatrixManipulator::getDistance() function. I
believe both were slips."

src/osgGA/KeySwitchMatrixManipulator.cpp

@@ -69,7 +69,7 @@ void KeySwitchMatrixManipulator::setDistance(double distance)
 
 double KeySwitchMatrixManipulator::getDistance() const
 {
-    if(!_current)
+    if(_current)
     {
         return _current->getDistance();
     }