From 08f6e874a8930899714e2c0d313a9ed9f4eec35c Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 14 Feb 2021 14:52:04 +0000
Subject: Link weak_ptrs

---
 game/network/link.h        |  3 ++-
 game/network/rail.cpp      |  4 ++--
 game/vehicles/railloco.cpp | 16 +++++++++-------
 game/vehicles/vehicle.h    |  2 +-
 4 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/game/network/link.h b/game/network/link.h
index d4ae4c6..207ecd0 100644
--- a/game/network/link.h
+++ b/game/network/link.h
@@ -28,6 +28,7 @@ using NodePtr = std::shared_ptr<Node>;
 // it joins 2 nodes
 class Link;
 using LinkPtr = std::shared_ptr<Link>;
+using LinkWPtr = std::weak_ptr<const Link>;
 class Link {
 public:
 	using End = std::pair<NodePtr, float /*dir*/>;
@@ -41,7 +42,7 @@ public:
 
 	std::array<End, 2> ends;
 	float length;
-	using Next = std::pair<LinkPtr, unsigned char /*end*/>;
+	using Next = std::pair<LinkWPtr, unsigned char /*end*/>;
 	std::array<std::vector<Next>, 2> nexts;
 };
 
diff --git a/game/network/rail.cpp b/game/network/rail.cpp
index 1f3cc01..10dfb88 100644
--- a/game/network/rail.cpp
+++ b/game/network/rail.cpp
@@ -24,8 +24,8 @@ RailLinks::joinLinks(const LinkPtr & l) const
 			for (const auto oe : {0, 1}) {
 				for (const auto te : {0, 1}) {
 					if (l->ends[te].first == ol->ends[oe].first) {
-						l->nexts[te].emplace_back(ol.get(), oe);
-						ol->nexts[oe].emplace_back(l.get(), te);
+						l->nexts[te].emplace_back(ol, oe);
+						ol->nexts[oe].emplace_back(l, te);
 					}
 				}
 			}
diff --git a/game/vehicles/railloco.cpp b/game/vehicles/railloco.cpp
index 54582c2..d06474c 100644
--- a/game/vehicles/railloco.cpp
+++ b/game/vehicles/railloco.cpp
@@ -12,23 +12,25 @@ void
 RailLoco::tick(TickDuration dur)
 {
 	linkDist += dur.count() * speed;
-	while (linkDist > link->length) {
-		location = link->positionAt(link->length, linkDir);
-		const auto & nexts {link->nexts[1 - linkDir]};
+	auto curLink {link.lock()};
+	while (linkDist > curLink->length) {
+		location = curLink->positionAt(curLink->length, linkDir);
+		const auto & nexts {curLink->nexts[1 - linkDir]};
 		const auto next = std::find_if(nexts.begin(), nexts.end(), [ang = location.GetRot().y](const Link::Next & n) {
-			return std::abs(normalize(n.first->ends[n.second].second - ang)) < 0.1F;
+			return std::abs(normalize(n.first.lock()->ends[n.second].second - ang)) < 0.1F;
 		});
 		if (next != nexts.end()) {
-			linkDist -= link->length;
+			linkDist -= curLink->length;
 			link = next->first;
+			curLink = link.lock();
 			linkDir = next->second;
 		}
 		else {
-			linkDist = link->length;
+			linkDist = curLink->length;
 			speed = 0;
 		}
 	}
-	location = link->positionAt(linkDist, linkDir);
+	location = curLink->positionAt(linkDist, linkDir);
 }
 
 Brush47::Brush47(const LinkPtr & l) : RailLoco(l, "brush47.obj", "brush47.png") { }
diff --git a/game/vehicles/vehicle.h b/game/vehicles/vehicle.h
index cd2249d..d59588c 100644
--- a/game/vehicles/vehicle.h
+++ b/game/vehicles/vehicle.h
@@ -9,7 +9,7 @@
 class Vehicle : public WorldObject, public Physical {
 public:
 	Vehicle(const LinkPtr & link, const std::string & obj, const std::string & tex);
-	LinkPtr link; // Which link are we travelling along
+	LinkWPtr link; // Which link are we travelling along
 	unsigned char linkDir {0}; // Starting end e0->e1 or e1->e0
 	float linkDist {0}; // distance long current link
 	float speed {50}; // speed in m/s (~75 km/h)
-- 
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