X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Flibr2c2%2Ftrainroutemetric.cpp;h=1fc4fcea2389d917ecaa90627791801dc0ee46e2;hb=5b71cb905051d654c150cb0e098cade0cb502105;hp=7e4d4856fe91a484f794470ce8a2e66a03151b96;hpb=3dd660ffad729fbd6e75e6401f5c7f27b9013faf;p=r2c2.git

diff --git a/source/libr2c2/trainroutemetric.cpp b/source/libr2c2/trainroutemetric.cpp
index 7e4d485..1fc4fce 100644
--- a/source/libr2c2/trainroutemetric.cpp
+++ b/source/libr2c2/trainroutemetric.cpp
@@ -9,6 +9,9 @@ namespace R2C2 {
 
 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)
 	{
@@ -31,6 +34,9 @@ TrainRouteMetric::TrainRouteMetric(const TrackChain &tc, TrackChain::Direction d
 		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();
@@ -62,6 +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));