From 446fa7ad737b431621be53a23360ea3bbe417fe5 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 27 Jan 2010 21:17:22 +0000
Subject: [PATCH] Fix some problems with loading routes Document some
 algorithms with comments Add paths to the double-slip turnout

---
 source/libmarklin/layout.cpp | 26 ++++++++++++++++++++------
 source/libmarklin/route.cpp  | 17 +++++++++++++++--
 tracks.dat                   |  6 +++++-
 3 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/source/libmarklin/layout.cpp b/source/libmarklin/layout.cpp
index 38336ae..afd5f03 100644
--- a/source/libmarklin/layout.cpp
+++ b/source/libmarklin/layout.cpp
@@ -114,9 +114,11 @@ void Layout::check_routes()
 {
 	for(map<string, Route *>::iterator i=routes.begin(); i!=routes.end(); ++i)
 	{
-		// We must copy the turnout map, since adding tracks to the route will (temporarily) mess it up
+		/* We must copy the turnout map, since adding tracks to the route will
+		(temporarily) mess it up */
 		const map<unsigned, int> turnouts = i->second->get_turnouts();
 
+		// Find any turnout in the route
 		Track *track = 0;
 		unsigned trk_path = 0;
 		for(set<Track *>::const_iterator j=tracks.begin(); j!=tracks.end(); ++j)
@@ -133,35 +135,47 @@ void Layout::check_routes()
 		if(!track)
 			continue;
 
-		i->second->add_track(*track);
-
+		// Find an applicable endpoint
 		const vector<Endpoint> &eps = track->get_type().get_endpoints();
 		unsigned ep = 0;
-		for(unsigned j=0; j<eps.size(); ++i)
+		for(unsigned j=0; j<eps.size(); ++j)
 			if(eps[j].paths&(1<<trk_path))
 			{
 				ep = j;
 				break;
 			}
 
-		Track *start = track;
+		Track *start = 0;
 		while(1)
 		{
+			// Traverse the track and get the next one
 			unsigned out_ep = track->traverse(ep, trk_path);
 			Track *next = track->get_links()[out_ep];
 			if(!next || next == start)
 				break;
+
 			ep = next->get_endpoint_by_link(*track);
 			if(next->get_type().get_n_paths()>1)
 			{
+				// Select correct path across the turnout, or break if we hit an unknown turnout
 				map<unsigned, int>::const_iterator j = turnouts.find(next->get_turnout_id());
 				if(j==turnouts.end())
 					break;
 				trk_path = j->second;
 			}
 			else
+			{
 				trk_path = 0;
-			i->second->add_track(*next);
+
+				/* Start adding tracks when we find the first non-turnout.  This
+				prevents the occurrence of ambiguities while adding the tracks */
+				if(!start)
+					start = next;
+			}
+
+			if(start)
+				i->second->add_track(*next);
+
 			track = next;
 		}
 	}
diff --git a/source/libmarklin/route.cpp b/source/libmarklin/route.cpp
index 40638d9..20017d2 100644
--- a/source/libmarklin/route.cpp
+++ b/source/libmarklin/route.cpp
@@ -92,17 +92,20 @@ void Route::update_turnouts()
 			const vector<Endpoint> &endpoints = (*i)->get_type().get_endpoints();
 			const vector<Track *> &links = (*i)->get_links();
 
+			// Build a combined path mask from linked endpoints
 			unsigned mask = 15;
 			for(unsigned j=0; j<endpoints.size(); ++j)
 			{
 				if(!tracks.count(links[j]))
 					continue;
+
 				if(unsigned tid2=links[j]->get_turnout_id())
 				{
 					const Endpoint &ep = links[j]->get_type().get_endpoints()[links[j]->get_endpoint_by_link(**i)];
 					int p = get_turnout(tid2);
 					if(p>=0 && !(ep.paths&(1<<p)))
 					{
+						// The linked track is a turnout and has a path which is incompatible with this endpoint
 						mask &= ~endpoints[j].paths;
 						continue;
 					}
@@ -110,16 +113,19 @@ void Route::update_turnouts()
 				mask &= endpoints[j].paths;
 			}
 
-			if(!(mask&(mask-1)))
+			if(mask && !(mask&(mask-1)))
 			{
+				// Exactly one possible choice, set the path accordingly
 				unsigned path = 0;
 				for(; (mask && !(mask&1)); mask>>=1, ++path) ;
 				turnouts[tid] = path;
 			}
-			else
+			else if(!turnouts.count(tid))
+				// More than one possible choice, and no existing entry - set as undecided
 				turnouts[tid] = -1;
 		}
 
+	// Remove any turnouts that do not exist in the route
 	for(map<unsigned, int>::iterator i=turnouts.begin(); i!=turnouts.end();)
 	{
 		if(!found.count(i->first))
@@ -137,6 +143,7 @@ unsigned Route::check_validity(const Track &trk) const
 		int epi=(*i)->get_endpoint_by_link(trk);
 		if(epi>=0)
 		{
+			// Linked to an existing track - good
 			result |= 1;
 			const vector<Endpoint> &endpoints = (*i)->get_type().get_endpoints();
 			if(unsigned tid=(*i)->get_turnout_id())
@@ -144,11 +151,13 @@ unsigned Route::check_validity(const Track &trk) const
 				int r = get_turnout(tid);
 				if(r>=0)
 				{
+					// Linking to a turnout with path set is only good if we're continuing that path
 					if(endpoints[epi].paths&(1<<r))
 						result |= 2;
 				}
 				else
 				{
+					// Linked to a turnout with no path set - find out other linked tracks 
 					unsigned count = 0;
 					const vector<Track *> &links = (*i)->get_links();
 					int epj = -1;
@@ -158,15 +167,19 @@ unsigned Route::check_validity(const Track &trk) const
 							++count;
 							epj = k;
 						}
+
+					// Only good if at most one other track is linked to the turnout
 					if(count<=1)
 					{
 						result |= 2;
 						if(epj>=0 && !(endpoints[epi].paths&endpoints[epj].paths))
+							// Impossible path through the turnout - not good
 							result &= 3;
 					}
 				}
 			}
 			else
+				// Linked to something linear - good
 				result |= 2;
 		}
 	}
diff --git a/tracks.dat b/tracks.dat
index 5fb597f..86089d0 100644
--- a/tracks.dat
+++ b/tracks.dat
@@ -312,26 +312,30 @@ track 24630
 
 track 24624
 {
-	description "Turnout, double crossing";
+	description "Turnout, double slip";
 	part
 	{
 		length 188.3;
+		path 0;
 	};
 	part
 	{
 		length 24.3;
 		radius -437.5;
+		path 1;
 	};
 	part
 	{
 		start 8.34 38.74 -24.3;
 		length 188.3;
+		path 2;
 	};
 	part
 	{
 		start 8.34 38.74 -24.3;
 		length 24.3;
 		radius 437.5;
+		path 3;
 	};
 };
 
-- 
2.45.2