Add UTC offset function

src/game/state/nuptial-flight.cpp

@@ -143,7 +143,7 @@ nuptial_flight::nuptial_flight(game::context& ctx):
 	}
 	
 	// Load biome
-	game::load::biome(ctx, "desert-scrub.bio");
+	game::load::biome(ctx, "debug.bio");
 	
 	// Set world time
 	game::world::set_time(ctx, 2022, 6, 21, 12, 0, 0.0);

src/game/world.cpp

@@ -41,6 +41,7 @@
 #include "physics/orbit/ephemeris.hpp"
 #include "physics/time/gregorian.hpp"
 #include "physics/time/constants.hpp"
+#include "physics/time/utc.hpp"
 #include "render/material.hpp"
 #include "render/model.hpp"
 #include "render/passes/shadow-map-pass.hpp"
@@ -116,7 +117,7 @@ void set_time(game::context& ctx, double t)
 
 void set_time(game::context& ctx, int year, int month, int day, int hour, int minute, double second)
 {
-	const double utc_offset = ctx.longitude / (math::two_pi<double> / 24.0);
+	const double utc_offset = physics::time::utc::offset<double>(ctx.longitude);
 	const double t = physics::time::gregorian::to_ut1<double>(year, month, day, hour, minute, second, utc_offset);
 	set_time(ctx, t);
 }

src/physics/time/time.hpp

@@ -31,5 +31,6 @@ namespace time {}
 #include "gregorian.hpp"
 #include "jd.hpp"
 #include "ut1.hpp"
+#include "utc.hpp"
 
 #endif // ANTKEEPER_PHYSICS_TIME_HPP

src/physics/time/utc.hpp

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2021  Christopher J. Howard
+ *
+ * This file is part of Antkeeper source code.
+ *
+ * Antkeeper source code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Antkeeper source code is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Antkeeper source code.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef ANTKEEPER_PHYSICS_TIME_UTC_HPP
+#define ANTKEEPER_PHYSICS_TIME_UTC_HPP
+
+#include "math/constants.hpp"
+
+namespace physics {
+namespace time {
+
+/// Coordinated Universal Time (UTC).
+namespace utc {
+
+/**
+ * Calculates the UTC offset at a given longitude
+ *
+ * @param longitude Longitude, in radians.
+ * @return UTC offset.
+ */
+template <class T>
+T offset(T longitude)
+{
+	return longitude / (math::two_pi<double> / 24.0);
+}
+
+} // namespace utc
+
+} // namespace time
+} // namespace physics
+
+#endif // ANTKEEPER_PHYSICS_TIME_UTC_HPP