From 3e8ce840c70ee00925210b96738696d1dc445f8f Mon Sep 17 00:00:00 2001
From: Rutger Broekhoff
Date: Tue, 8 Sep 2026 01:36:38 +0200
Subject: UTM projection

---
 server/src/geo/utm_zone_local.cppm | 74 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 server/src/geo/utm_zone_local.cppm

(limited to 'server/src/geo/utm_zone_local.cppm')

diff --git a/server/src/geo/utm_zone_local.cppm b/server/src/geo/utm_zone_local.cppm
new file mode 100644
index 0000000..98a1344
--- /dev/null
+++ b/server/src/geo/utm_zone_local.cppm
@@ -0,0 +1,74 @@
+module;
+
+#include <boost/geometry.hpp>
+#include <boost/geometry/geometries/register/linestring.hpp>
+
+export module routemon:geo.utm.zone_local;
+
+import :geo;
+import :geo.utm;
+
+// Coordinates that are local to some known UTM zone.
+namespace routemon::geo::utm::zone_local {
+
+  using cs = bgeo::cs::cartesian;
+
+  namespace prim {
+
+    using point = bgeo::model::d2::point_xy<double>;
+    using linestring = bgeo::model::linestring<point>;
+    using box = bgeo::model::box<point>;
+
+  } // namespace prim
+
+  struct point : public prim::point
+  {
+    zone zone;
+
+    explicit point(class zone zone, double x, double y)
+      : prim::point{x, y}, zone{zone}
+    {
+    }
+  };
+
+  struct linestring : public prim::linestring
+  {
+    zone zone;
+
+    explicit linestring(class zone zone)
+      : zone{zone}
+    {
+    }
+  };
+
+} // namespace routemon::geo::utm::zone_local
+
+BOOST_GEOMETRY_REGISTER_LINESTRING(routemon::geo::utm::zone_local::linestring)
+
+namespace boost::geometry::traits {
+
+  namespace {
+
+    using zone_local_point = routemon::geo::utm::zone_local::point;
+
+  } // namespace <anonymous>
+
+  template<> struct tag<zone_local_point> { using type = point_tag; };
+  template<> struct dimension<zone_local_point> : boost::mpl::int_<2> {};
+  template<> struct coordinate_type<zone_local_point> { using type = double; };
+  template<> struct coordinate_system<zone_local_point> { using type = routemon::geo::utm::zone_local::cs; };
+
+  template<std::size_t index>
+  struct access<zone_local_point, index> {
+    static inline auto get(zone_local_point const& p) -> double
+    {
+      return bgeo::get<index>(static_cast<routemon::geo::utm::zone_local::prim::point const&>(p));
+    }
+
+    static inline auto set(zone_local_point& p, double v) -> void
+    {
+      return bgeo::set<index>(static_cast<routemon::geo::utm::zone_local::prim::point&>(p), v);
+    }
+  };
+
+} // namespace boost::geometry::traits
-- 
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