+template<>
+const set<Terrain *> &Layout::get_all<Terrain>() const
+{
+ return objects.get<Terrain>();
+}
+
+template<>
+const set<TrackChain *> &Layout::get_all<TrackChain>() const
+{
+ return track_chains.get();
+}
+
+template<>
+const set<Block *> &Layout::get_all<Block>() const
+{
+ return track_chains.get<Block>();
+}
+
+template<>
+const set<Route *> &Layout::get_all<Route>() const
+{
+ return track_chains.get<Route>();
+}
+
+template<>
+const set<Zone *> &Layout::get_all<Zone>() const
+{
+ return track_chains.get<Zone>();
+}
+
+template<>
+const set<Sensor *> &Layout::get_all<Sensor>() const
+{
+ return sensors.get<Sensor>();
+}
+
+template<>
+const set<TrackCircuit *> &Layout::get_all<TrackCircuit>() const
+{
+ return sensors.get<TrackCircuit>();
+}
+
+template<>
+const set<BeamGate *> &Layout::get_all<BeamGate>() const
+{
+ return sensors.get<BeamGate>();
+}
+
+template<typename T>
+T *Layout::pick(const Ray &ray)
+{
+ const set<Object *> &objs = objects.get();
+ T *closest = 0;
+ float distance = -1;
+ for(set<Object *>::const_iterator i=objs.begin(); i!=objs.end(); ++i)
+ if(T *t = dynamic_cast<T *>(*i))
+ {
+ float d = -1;
+ if(t->collide_ray(ray, &d))
+ if(!closest || d<distance)
+ {
+ closest = t;
+ distance = d;
+ }
+ }
+
+ return closest;