+Object *Layout::pick_object(const Ray &ray)
+{
+ if(Object *obj = pick_track(ray))
+ return obj;
+ else if((obj = pick_signal(ray)))
+ return obj;
+ return 0;
+}
+
+template<typename T>
+T *Layout::pick(const set<T *> &objs, const Ray &ray)
+{
+ for(typename set<T *>::const_iterator i=objs.begin(); i!=objs.end(); ++i)
+ if((*i)->collide_ray(ray))
+ return *i;
+
+ return 0;
+}
+