Added beginnings of osgUtil::PlaneIntersector and osgSim::ElevationSlice

include/osgUtil/IntersectionVisitor

@@ -215,6 +215,67 @@ class OSGUTIL_EXPORT PolytopeIntersector : public Intersector
     
 };
 
+/** Concrent class for implementing polytope intersections with the scene graph.
+  * To be used in conjunction with IntersectionVisitor. */
+class OSGUTIL_EXPORT PlaneIntersector : public Intersector
+{
+    public:
+    
+        /** Construct a PolytopeIntersector using speified polytope in MODEL coordinates.*/
+        PlaneIntersector(const osg::Plane& plane, const osg::Polytope& boundingPolytope=osg::Polytope());
+        
+        /** Construct a PolytopeIntersector using speified polytope in specified coordinate frame.*/
+        PlaneIntersector(CoordinateFrame cf, const osg::Plane& plane, const osg::Polytope& boundingPolytope=osg::Polytope());
+
+        struct Intersection
+        {
+            Intersection() {}
+        
+            bool operator < (const Intersection& rhs) const
+            {
+                if (nodePath < rhs.nodePath) return true;
+                if (rhs.nodePath < nodePath ) return false;
+                return (drawable < rhs.drawable);
+            }
+
+            osg::NodePath                   nodePath;
+            osg::ref_ptr<osg::Drawable>     drawable;
+        };
+        
+        typedef std::set<Intersection> Intersections;
+        
+        inline void insertIntersection(const Intersection& intersection) { getIntersections().insert(intersection); }
+
+        inline Intersections& getIntersections() { return _parent ? _parent->_intersections : _intersections; }
+
+        inline Intersection getFirstIntersection() { Intersections& intersections = getIntersections(); return intersections.empty() ? Intersection() : *(intersections.begin()); }
+
+    public:
+
+        virtual Intersector* clone(osgUtil::IntersectionVisitor& iv);
+        
+        virtual bool enter(const osg::Node& node);
+        
+        virtual void leave();
+        
+        virtual void intersect(osgUtil::IntersectionVisitor& iv, osg::Drawable* drawable);
+        
+        virtual void reset();
+
+        virtual bool containsIntersections() { return !_intersections.empty(); }
+
+    protected:
+
+        PlaneIntersector*   _parent;
+
+        osg::Plane          _plane;
+        osg::Polytope       _polytope;
+        
+        Intersections       _intersections;
+    
+};
+
+
 /** Concrent class for passing multiple intersectors through the scene graph.
   * To be used in conjunction with IntersectionVisitor. */
 class OSGUTIL_EXPORT IntersectorGroup : public Intersector