Skip local light calculation on map not using any ToD areas

src/display.cpp

@@ -1945,7 +1945,7 @@ void display::draw(bool update,bool force) {
 		return;
 	}
 
-	local_tod_light_ = preferences::get("local_tod_light", false);
+	local_tod_light_ = has_time_area() && preferences::get("local_tod_light", false);
 
 	bool changed = draw_init();
 	pre_draw();

src/display.hpp

@@ -471,6 +471,8 @@ public:
 
 	virtual const time_of_day& get_time_of_day(const map_location& /*loc*/) const;
 
+	virtual bool has_time_area() const {return false;};
+
 protected:
 	/** Clear the screen contents */
 	void clear_screen();

src/game_display.cpp

@@ -423,6 +423,11 @@ const time_of_day& game_display::get_time_of_day(const map_location& loc) const
 	return tod_manager_.get_time_of_day(loc);
 }
 
+bool game_display::has_time_area() const
+{
+	return tod_manager_.has_time_area();
+}
+
 void game_display::draw_report(reports::TYPE report_num)
 {
 	if(!team_valid()) {

src/game_display.hpp

@@ -146,6 +146,8 @@ public:
 
 	const time_of_day& get_time_of_day(const map_location& loc) const;
 
+	bool has_time_area() const;
+
 protected:
 	/**
 	 * game_display pre_draw does specific things related e.g. to unit rendering

src/tod_manager.hpp

@@ -87,6 +87,8 @@ class tod_manager : public savegame::savegame_config
 		 */
 		void remove_time_area(const std::string& id);
 
+		bool has_time_area() const {return !areas_.empty();};
+
 		const std::vector<time_of_day> times() const {return times_;}
 
 		//consider tod modifying units (e.g. illuminates)