Added initial interface for computing intersections between sphere segments

and terrain.

examples/osgsimulation/osgsimulation.cpp

@@ -323,7 +323,7 @@ int main(int argc, char **argv)
             
             // tell the overlay node to continously update its overlay texture
             // as we know we'll be tracking a moving target.
-            // overlayNode->setContinousUpdate(true);
+            overlayNode->setContinousUpdate(true);
         }