From 1bcce010b5b11b485ba80df58c984277100dc99e Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 11 May 2025 00:12:42 +0100
Subject: Fix conditional render of rail links

Tests for vertices, not links in network. Fixes case where links are
present but not in network, e.g. currently being built.
---
 game/network/network.h      | 1 +
 game/network/network.impl.h | 7 +++++++
 game/network/rail.cpp       | 2 +-
 gfx/gl/instanceVertices.h   | 1 +
 4 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/game/network/network.h b/game/network/network.h
index 0c499c6..c1d3265 100644
--- a/game/network/network.h
+++ b/game/network/network.h
@@ -135,4 +135,5 @@ public:
 
 protected:
 	Link::CCollection addCurve(const GeoData *, const GenCurveDef &);
+	[[nodiscard]] bool anyLinks() const;
 };
diff --git a/game/network/network.impl.h b/game/network/network.impl.h
index 7f7dfb3..04c5d7c 100644
--- a/game/network/network.impl.h
+++ b/game/network/network.impl.h
@@ -160,6 +160,13 @@ NetworkOf<T, Links...>::create(const GenCurveDef & def)
 			*this, candidateNodeAt(std::get<0>(def)).first, candidateNodeAt(std::get<1>(def)).first, std::get<2>(def));
 }
 
+template<typename T, typename... Links>
+bool
+NetworkOf<T, Links...>::anyLinks() const
+{
+	return !(static_cast<const NetworkLinkHolder<Links> *>(this)->vertices.empty() && ...);
+}
+
 template<typename T, typename... Links>
 void
 NetworkOf<T, Links...>::add(GeoData * geoData, const Link::Ptr & link)
diff --git a/game/network/rail.cpp b/game/network/rail.cpp
index c0e597d..37eb7df 100644
--- a/game/network/rail.cpp
+++ b/game/network/rail.cpp
@@ -169,7 +169,7 @@ namespace {
 void
 RailLinks::render(const SceneShader & shader, const Frustum &) const
 {
-	if (!links.empty()) {
+	if (anyLinks()) {
 		texture->bind();
 		glEnable(GL_POLYGON_OFFSET_FILL);
 		glPolygonOffset(-1, 0);
diff --git a/gfx/gl/instanceVertices.h b/gfx/gl/instanceVertices.h
index 28e11ee..c290afe 100644
--- a/gfx/gl/instanceVertices.h
+++ b/gfx/gl/instanceVertices.h
@@ -118,6 +118,7 @@ public:
 	}
 
 	using base::bufferName;
+	using base::empty;
 
 	[[nodiscard]] auto
 	size() const
-- 
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