gun_example.cpp

struct BulletCount {
	int32_t count;
};

struct Damage {
	float value;
};

int main(int argc, char * argv[]) {
	flecs::world world(argc, argv);

	// Declare components
	flecs::component<BulletCount>(world, "BulletCount");
	flecs::component<Damage>(world, "Damage");

	// System that assigns random value to Damage upon
	// adding the Damage component
	flecs::system<Damage>(world)
		.kind(flecs::OnAdd)
		.each([](flecs::entity e, Damage &dmg) {
			dmg.value = ((float)rand() / (float)RAND_MAX) * 3 + 20;
		});

	// Gun template with bullet count of 6
	auto Gun = flecs::prefab(world, "Gun")
		.set<BulletCount>({6});

	// The fun part: create a reusable type that
	// contains both the gun and the damage component.
	// Each gun created with this type will have
	// 6 bullets and a random damage value
	auto RandomDmgGun = flecs::type(world, "RandomDmgGun")
		.add_instanceof(Gun)
		.add<Damage>();

	// Instantiate the random gun type
	auto my_gun = flecs::entity(world)
		.add(RandomDmgGun);

	// Outputs 6
	BulletCount* bullets = my_gun.get_ptr<BulletCount>();
	std::cout << bullets->count << std::endl;

	// Outputs random value
	Damage* damage = my_gun.get_ptr<Damage>();
	std::cout << damage->value << std::endl;

	return 0;	
}