From 2e66a686cd6cf589c583060921430a94b2849e83 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 21 Dec 2024 14:10:01 +0000
Subject: Expose network link interface to define a base area of the link

---
 game/network/link.cpp | 35 +++++++++++++++++++++++++++++++++++
 game/network/link.h   |  3 +++
 2 files changed, 38 insertions(+)

(limited to 'game/network')

diff --git a/game/network/link.cpp b/game/network/link.cpp
index 79af92a..61e8771 100644
--- a/game/network/link.cpp
+++ b/game/network/link.cpp
@@ -38,6 +38,20 @@ LinkStraight::intersectRay(const Ray<GlobalPosition3D> & ray) const
 			std::array {GlobalPosition3D {ends.front().node->pos}, GlobalPosition3D {ends.back().node->pos}}, 1000);
 }
 
+std::vector<GlobalPosition3D>
+LinkStraight::getBase(RelativeDistance width) const
+{
+	const auto start = ends.front().node->pos;
+	const auto end = ends.back().node->pos;
+	const auto direction = (vector_normal(normalize(::difference(start, end).xy())) * width / 2.F) || 0.F;
+	return {
+			start - direction,
+			start + direction,
+			end - direction,
+			end + direction,
+	};
+}
+
 Location
 LinkCurve::positionAt(float dist, unsigned char start) const
 {
@@ -73,3 +87,24 @@ LinkCurve::intersectRay(const Ray<GlobalPosition3D> & ray) const
 	}
 	return ray.passesCloseToEdges(points, 1.F);
 }
+
+std::vector<GlobalPosition3D>
+LinkCurve::getBase(RelativeDistance width) const
+{
+	const auto start = ends.front().node->pos;
+	const auto end = ends.back().node->pos;
+	const auto segs = std::ceil(15.F * arc.length());
+	const auto step {glm::vec<2, RelativeDistance> {arc.length(), end.z - start.z} / segs};
+
+	auto segCount = static_cast<size_t>(segs) + 1;
+	std::vector<GlobalPosition3D> out;
+	out.reserve(segCount);
+	for (RelativePosition2D swing = {arc.first, centreBase.z - start.z}; segCount != 0U; swing += step, --segCount) {
+		const auto direction = sincos(swing.x);
+		const auto linkCentre = centreBase + ((direction * radius) || swing.y);
+		const auto toEdge = (direction * width / 2.F) || 0.F;
+		out.emplace_back(linkCentre + toEdge);
+		out.emplace_back(linkCentre - toEdge);
+	}
+	return out;
+}
diff --git a/game/network/link.h b/game/network/link.h
index 4cca52c..59bbb65 100644
--- a/game/network/link.h
+++ b/game/network/link.h
@@ -45,6 +45,7 @@ public:
 
 	[[nodiscard]] virtual Location positionAt(RelativeDistance dist, unsigned char start) const = 0;
 	[[nodiscard]] virtual bool intersectRay(const Ray<GlobalPosition3D> &) const = 0;
+	[[nodiscard]] virtual std::vector<GlobalPosition3D> getBase(RelativeDistance width) const = 0;
 
 	std::array<End, 2> ends;
 	float length;
@@ -69,6 +70,7 @@ public:
 
 	[[nodiscard]] Location positionAt(RelativeDistance dist, unsigned char start) const override;
 	[[nodiscard]] bool intersectRay(const Ray<GlobalPosition3D> &) const override;
+	[[nodiscard]] std::vector<GlobalPosition3D> getBase(RelativeDistance width) const override;
 };
 
 LinkStraight::~LinkStraight() = default;
@@ -82,6 +84,7 @@ public:
 
 	[[nodiscard]] Location positionAt(RelativeDistance dist, unsigned char start) const override;
 	[[nodiscard]] bool intersectRay(const Ray<GlobalPosition3D> &) const override;
+	[[nodiscard]] std::vector<GlobalPosition3D> getBase(RelativeDistance width) const override;
 
 	GlobalPosition3D centreBase;
 	RelativeDistance radius;
-- 
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