From dd80098076cda9c103b44356ca07c2c8bc7698d7 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 14 Feb 2021 13:14:32 +0000
Subject: Join links in rail graph

---
 game/network/link.h   |  5 +++++
 game/network/rail.cpp | 17 +++++++++++++++++
 game/network/rail.h   |  5 ++++-
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/game/network/link.h b/game/network/link.h
index 287ba14..c9fbedb 100644
--- a/game/network/link.h
+++ b/game/network/link.h
@@ -6,6 +6,7 @@
 #include <memory>
 #include <special_members.hpp>
 #include <utility>
+#include <vector>
 
 // Generic network node
 // something that can be travelled to
@@ -24,6 +25,8 @@ using NodePtr = std::shared_ptr<Node>;
 // Generic network link
 // something that can be travelled along
 // it joins 2 nodes
+class Link;
+using LinkPtr = std::shared_ptr<Link>;
 class Link {
 public:
 	using End = std::pair<NodePtr, float /*dir*/>;
@@ -35,6 +38,8 @@ public:
 
 	std::array<End, 2> ends;
 	float length;
+	using Next = std::pair<LinkPtr, unsigned char /*end*/>;
+	std::array<std::vector<Next>, 2> nexts;
 };
 
 bool operator<(const glm::vec3 & a, const glm::vec3 & b);
diff --git a/game/network/rail.cpp b/game/network/rail.cpp
index fd2ea08..a66bf65 100644
--- a/game/network/rail.cpp
+++ b/game/network/rail.cpp
@@ -15,6 +15,23 @@
 RailLinks::RailLinks() : texture {Texture::cachedTexture.get("rails.jpg")} { }
 void RailLinks::tick(TickDuration) { }
 
+void
+RailLinks::joinLinks(LinkPtr l) const
+{
+	for (const auto & ol : links.objects) {
+		if (l != ol) {
+			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);
+					}
+				}
+			}
+		}
+	}
+}
+
 void
 RailLinks::render(const Shader & shader) const
 {
diff --git a/game/network/rail.h b/game/network/rail.h
index 5fea713..a501f32 100644
--- a/game/network/rail.h
+++ b/game/network/rail.h
@@ -61,7 +61,9 @@ public:
 	{
 		const auto node1 = *nodes.insert(std::make_shared<Node>(a)).first;
 		const auto node2 = *nodes.insert(std::make_shared<Node>(b)).first;
-		return links.create<T>(node1, node2, std::forward<Params>(params)...);
+		auto l = links.create<T>(node1, node2, std::forward<Params>(params)...);
+		joinLinks(l);
+		return l;
 	}
 
 private:
@@ -70,6 +72,7 @@ private:
 	Nodes nodes;
 	void render(const Shader &) const override;
 	void tick(TickDuration elapsed) override;
+	void joinLinks(LinkPtr) const;
 	std::shared_ptr<Texture> texture;
 };
 
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