Add an actual heuristic for wait time

[r2c2.git] / source / libr2c2 / trainroutemetric.cpp

diff --git a/source/libr2c2/trainroutemetric.cpp b/source/libr2c2/trainroutemetric.cpp
index a2cffbc896504d7df252905a449c63fbbe11c91b..1fc4fcea2389d917ecaa90627791801dc0ee46e2 100644 (file)
--- a/source/libr2c2/trainroutemetric.cpp
+++ b/source/libr2c2/trainroutemetric.cpp
@@ -7,16 +7,24 @@ using namespace std;
 
 namespace R2C2 {
 
-TrainRouteMetric::TrainRouteMetric(const TrackChain &tc)
+TrainRouteMetric::TrainRouteMetric(const TrackChain &tc, TrackChain::Direction dir)
 {
+       /* Initialize goals for tracks in the target chain.  We travel outwards from
+       the target in the search phase so the iters appear to point the wrong way. */
+       TrackChain::Direction reverse_dir = (dir==TrackChain::DOWN ? TrackChain::UP : TrackChain::DOWN);
        const TrackChain::TrackSet &ctracks = tc.get_tracks();
        for(TrackChain::TrackSet::const_iterator i=ctracks.begin(); i!=ctracks.end(); ++i)
        {
-               unsigned nls = (*i)->get_n_link_slots();
-               for(unsigned j=0; j<nls; ++j)
-                       if(Track *link = (*i)->get_link(j))
-                               if(!ctracks.count(link))
-                                       goals.push_back(TrackIter(*i, j));
+               if(dir==TrackChain::UNSPECIFIED)
+               {
+                       unsigned nls = (*i)->get_n_link_slots();
+                       for(unsigned j=0; j<nls; ++j)
+                               if(Track *link = (*i)->get_link(j))
+                                       if(!ctracks.count(link))
+                                               goals.push_back(TrackIter(*i, j));
+               }
+               else if(TrackIter iter = tc.iter_for(**i, reverse_dir))
+                       goals.push_back(iter);
        }
 
        list<TrackIter> queue;
@@ -26,6 +34,9 @@ TrainRouteMetric::TrainRouteMetric(const TrackChain &tc)
                queue.push_back(i->track);
        }
 
+       /* Use Dijkstra's algorithm to find the shortest distance from the goal to
+       every reachable track in the layout.  Entry points here become exit points
+       when looking up distances to the goal. */
        while(!queue.empty())
        {
                TrackIter track = queue.front();
@@ -57,6 +68,22 @@ void TrainRouteMetric::chain_to(const TrainRouteMetric &metric)
                i->base_distance = metric.get_distance_from(*i->track.track(), i->track.entry());
 }
 
+float TrainRouteMetric::get_distance_from(const Track &track) const
+{
+       map<Key, Data>::const_iterator i = tracks.lower_bound(Key(&track, 0));
+       map<Key, Data>::const_iterator j = tracks.upper_bound(Key(&track, 255));
+
+       float result = -1;
+       for(; i!=j; ++i)
+       {
+               float d = i->second.distance+i->second.goal->base_distance;
+               if(result<0 || d<result)
+                       result = d;
+       }
+
+       return result;
+}
+
 float TrainRouteMetric::get_distance_from(const Track &track, unsigned exit) const
 {
        map<Key, Data>::const_iterator i = tracks.find(Key(&track, exit));