Properly link flecs library

engine/libs/flecs/examples/cpp/reflection/units/src/main.cpp

@@ -0,0 +1,50 @@
+#include <units.h>
+#include <iostream>
+
+struct WeatherStation {
+    double temperature;
+    double pressure;
+    double precipitation;
+};
+
+void print_value(const flecs::cursor& cur) {
+    // Get unit entity and component
+    flecs::entity u = cur.get_unit();
+    const flecs::Unit *u_data = u.get<flecs::Unit>();
+
+    // Print value with unit symbol
+    std::cout << cur.get_member() << ": " << cur.get_float() 
+        << " " << u_data->symbol << "\n";
+}
+
+int main(int, char *[]) {
+    flecs::world ecs;
+
+    // Import units module.
+    ecs.import<flecs::units>();
+
+    // Register reflection data with units. This can improve the way information
+    // is visualized in tools, such as the explorer.
+    ecs.component<WeatherStation>()
+        .member<double, flecs::units::temperature::Celsius>("temperature")
+        .member<double, flecs::units::pressure::Bar>("pressure")
+        .member<double, flecs::units::length::MilliMeters>("precipitation");
+
+    flecs::entity e = ecs.entity().set<WeatherStation>({24, 1.2, 0.5});
+
+    // Use cursor API to print values with units
+    WeatherStation *ptr = e.get_mut<WeatherStation>();
+    flecs::cursor cur = ecs.cursor<WeatherStation>(ptr);
+    cur.push();
+    print_value(cur);
+    cur.next();
+    print_value(cur);
+    cur.next();
+    print_value(cur);
+    cur.pop();
+
+    // Output:
+    //  temperature: 24 °C
+    //  pressure: 1.2 bar
+    //  precipitation: 0.5 mm
+}