From c3b032626c841e180e67aed6093397b8caafbd6c Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Thu, 13 Oct 2022 20:00:30 +0100
Subject: Support searching node network by vec3 position

---
 game/network/network.h |  2 +-
 lib/sorting.hpp        | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/game/network/network.h b/game/network/network.h
index 79a4a2b..34e6a60 100644
--- a/game/network/network.h
+++ b/game/network/network.h
@@ -37,7 +37,7 @@ public:
 protected:
 	static void joinLinks(const LinkPtr & l, const LinkPtr & ol);
 
-	using Nodes = std::set<NodePtr, PtrSorter<NodePtr>>;
+	using Nodes = std::set<NodePtr, PtrMemberSorter<NodePtr, &Node::pos>>;
 	Nodes nodes;
 	std::shared_ptr<Texture> texture;
 };
diff --git a/lib/sorting.hpp b/lib/sorting.hpp
index 6b9be6a..0604aaf 100644
--- a/lib/sorting.hpp
+++ b/lib/sorting.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <type_traits>
+
 template<typename T> struct PtrSorter {
 	bool
 	operator()(const T & a, const T & b) const
@@ -7,3 +9,22 @@ template<typename T> struct PtrSorter {
 		return *a < *b;
 	}
 };
+
+template<typename T, auto M> struct PtrMemberSorter : public PtrSorter<T> {
+	using MT = std::decay_t<decltype((*T {}).*M)>;
+	using is_transparent = MT;
+
+	using PtrSorter<T>::operator();
+
+	bool
+	operator()(const MT & a, const T & b) const
+	{
+		return a < (*b).*M;
+	}
+
+	bool
+	operator()(const T & a, const MT & b) const
+	{
+		return (*a).*M < b;
+	}
+};
-- 
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