From d7587defa3cedd6e7ea6d0623aa8cd0f6b27819c Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 2 Oct 2022 18:16:27 +0100
Subject: Add support for searching a network for a ray intersection

---
 game/network/network.cpp    | 17 +++++++++++++++++
 game/network/network.h      | 10 ++++++++++
 game/network/network.impl.h | 15 +++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/game/network/network.cpp b/game/network/network.cpp
index f59fe1e..775d420 100644
--- a/game/network/network.cpp
+++ b/game/network/network.cpp
@@ -5,7 +5,9 @@
 #include <filesystem>
 #include <game/network/link.h>
 #include <gfx/models/texture.h>
+#include <glm/gtx/intersect.hpp>
 #include <initializer_list>
+#include <ray.hpp>
 #include <stdexcept>
 #include <utility>
 
@@ -33,6 +35,21 @@ Network::findNodeAt(glm::vec3 pos) const
 	return {};
 }
 
+Network::IntersectRayResult
+Network::intersectRay(const Ray & ray) const
+{
+	// Click within 2m of a node
+	if (const auto node = std::find_if(nodes.begin(), nodes.end(),
+				[&ray](const NodePtr & node) {
+					glm::vec3 ipos, inorm;
+					return glm::intersectRaySphere(ray.start, ray.direction, node->pos, 2.F, ipos, inorm);
+				});
+			node != nodes.end()) {
+		return *node;
+	}
+	return intersectRayLinks(ray);
+}
+
 void
 Network::joinLinks(const LinkPtr & l, const LinkPtr & ol)
 {
diff --git a/game/network/network.h b/game/network/network.h
index 2ce45f7..64f3f91 100644
--- a/game/network/network.h
+++ b/game/network/network.h
@@ -9,23 +9,30 @@
 #include <sorting.hpp>
 #include <string>
 #include <utility>
+#include <variant>
 
 class Texture;
 class Shader;
+class Ray;
 
 class Network {
 public:
+	using LinkEnd = std::pair<LinkPtr, unsigned char>;
+	using IntersectRayResult = std::variant<std::nullptr_t, NodePtr, LinkEnd, LinkPtr>;
 	explicit Network(const std::string & textureName);
+	virtual ~Network() = default;
 
 	[[nodiscard]] NodePtr findNodeAt(glm::vec3) const;
 	[[nodiscard]] NodePtr nodeAt(glm::vec3);
 	[[nodiscard]] std::pair<NodePtr, bool> newNodeAt(glm::vec3);
+	[[nodiscard]] IntersectRayResult intersectRay(const Ray &) const;
 
 	[[nodiscard]] Link::Nexts routeFromTo(const Link::End &, glm::vec3) const;
 	[[nodiscard]] Link::Nexts routeFromTo(const Link::End &, const NodePtr &) const;
 
 protected:
 	static void joinLinks(const LinkPtr & l, const LinkPtr & ol);
+	[[nodiscard]] virtual IntersectRayResult intersectRayLinks(const Ray &) const = 0;
 
 	using Nodes = std::set<NodePtr, PtrSorter<NodePtr>>;
 	Nodes nodes;
@@ -39,6 +46,9 @@ protected:
 	Collection<T> links;
 	void joinLinks(const LinkPtr &) const;
 
+protected:
+	[[nodiscard]] IntersectRayResult intersectRayLinks(const Ray &) const override;
+
 public:
 	template<typename L, typename... Params>
 	std::shared_ptr<L>
diff --git a/game/network/network.impl.h b/game/network/network.impl.h
index d2e9ff0..afc9304 100644
--- a/game/network/network.impl.h
+++ b/game/network/network.impl.h
@@ -21,3 +21,18 @@ NetworkOf<T>::joinLinks(const LinkPtr & l) const
 		Network::joinLinks(l, ol);
 	}
 }
+
+template<typename T>
+Network::IntersectRayResult
+NetworkOf<T>::intersectRayLinks(const Ray & ray) const
+{
+	// Click link
+	if (const auto link = std::find_if(links.objects.begin(), links.objects.end(),
+				[&ray](const std::shared_ptr<T> & link) {
+					return link->intersectRay(ray);
+				});
+			link != links.objects.end()) {
+		return *link;
+	}
+	return {};
+}
-- 
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