prefabs/hierarchy

• C

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  #include <hierarchy.h>
  #include <stdio.h>
   
  // When a prefab has children, they are instantiated for an instance when the
  // IsA relationship to the prefab is added.
   
  int main(int argc, char *argv[]) {
      ecs_world_t *ecs = ecs_init_w_args(argc, argv);
   
      // Create a prefab hierarchy.
      ecs_entity_t SpaceShip = ecs_entity(ecs, { .name = "SpaceShip" });
      ecs_add_id(ecs, SpaceShip, EcsPrefab);
          ecs_entity_t SpaceShipEngine = ecs_entity(ecs, { .name = "Engine" });
          ecs_add_id(ecs, SpaceShipEngine, EcsPrefab);
          ecs_add_pair(ecs, SpaceShipEngine, EcsChildOf, SpaceShip);
      
          ecs_entity_t SpaceShipCockpit = ecs_entity(ecs, { .name = "Cockpit" });
          ecs_add_id(ecs, SpaceShipCockpit, EcsPrefab);
          ecs_add_pair(ecs, SpaceShipCockpit, EcsChildOf, SpaceShip);
   
      // Instantiate the prefab. This also creates an Engine and Cockpit child
      // for the instance.
      ecs_entity_t inst = ecs_entity(ecs, { .name = "my_spaceship" });
      ecs_add_pair(ecs, inst, EcsIsA, SpaceShip);
      ecs_entity_t inst_engine = ecs_lookup_child(ecs, inst, "Engine");
      ecs_entity_t inst_cockpit = ecs_lookup_child(ecs, inst, "Cockpit");
   
      char *path = ecs_get_path(ecs, inst_engine);
      printf("instance engine:  %s\n", path);
      ecs_os_free(path);
   
      path = ecs_get_path(ecs, inst_cockpit);
      printf("instance cockpit: %s\n", path);
      ecs_os_free(path);
   
      // Output:
      //  instance engine:  my_spaceship.Engine
      //  instance cockpit: my_spaceship.Cockpit
   
      return ecs_fini(ecs);
  }

• C++

  View on GitHub

  #include <hierarchy.h>
  #include <iostream>
   
  // When a prefab has children, they are instantiated for an instance when the
  // IsA relationship to the prefab is added.
   
  int main() {
      flecs::world ecs;
   
      // Create a prefab hierarchy.
      flecs::entity SpaceShip = ecs.prefab("SpaceShip");
          ecs.prefab("Engine").child_of(SpaceShip);
          ecs.prefab("Cockpit").child_of(SpaceShip);
   
      // Instantiate the prefab. This also creates an Engine and Cockpit child
      // for the instance.
      flecs::entity inst = ecs.entity("my_spaceship").is_a(SpaceShip);
      flecs::entity inst_engine = inst.lookup("Engine");
      flecs::entity inst_cockpit = inst.lookup("Cockpit");
   
      std::cout << "instance engine:  " << inst_engine.path() << "\n";
      std::cout << "instance cockpit: " << inst_cockpit.path() << "\n";
   
      // Output:
      //   instance engine:  ::my_spaceship::Engine
      //   instance cockpit: ::my_spaceship::Cockpit
  }